Multitasking the code ARC3D. [for computational fluid dynamics
NASA Technical Reports Server (NTRS)
Barton, John T.; Hsiung, Christopher C.
1986-01-01
The CRAY multitasking system was developed in order to utilize all four processors and sharply reduce the wall clock run time. This paper describes the techniques used to modify the computational fluid dynamics code ARC3D for this run and analyzes the achieved speedup. The ARC3D code solves either the Euler or thin-layer N-S equations using an implicit approximate factorization scheme. Results indicate that multitask processing can be used to achieve wall clock speedup factors of over three times, depending on the nature of the program code being used. Multitasking appears to be particularly advantageous for large-memory problems running on multiple CPU computers.
Dynamic coupling between fluid flow and vein growth in fractures: a 3D numerical model
NASA Astrophysics Data System (ADS)
Schwarz, J.-O.; Enzmann, F.
2012-04-01
Fluid flow is one of the main mass transport mechanisms in the Earth's crust and abundant mineral vein networks are important indicators for fluid flow and fluid rock interaction. These systems are dynamic and part of the so called RTM processes (reaction-transport-mechanics). Understanding of mineral vein systems requires coupling of these processes. Here we present a conceptional model for dynamic vein growth of syntaxial, posttectonic veins generated by advective fluid flow and show first results of a numerical model for this scenario. Vein generation requires three processes to occur: (i) fracture generation by mechanical stress e.g. hydro-fracturing, (ii) flow of a supersaturated fluid on that fracture and (iii) crystallization of phase(s) on or in the fracture. 3D synthetic fractures are generated with the SynFrac code (Ogilvie, et al. 2006). Subsequently solutions of the Navier-Stokes equation for this fracture are computed by a computational fluid dynamics code called GeoDict (Wiegmann 2007). Transport (advective and diffusive) of chemical species to growth sites in the fracture and vein growth are computed by a self-written MATLAB script. The numerical model discretizes the wall rock and fracture geometry by volumetric pixels (voxels). Based on this representation, the model computes the three basic functions for vein generation: (a) nucleation, (b) fluid flow with transport of chemical species and (c) growth. The following conditions were chosen for these three modules. Nucleation is heterogeneous and occurs instantaneously at the wall rock/fracture interface. Advective and diffusive flow of a supersaturated fluid and related transport of chemical species occurs according to the computed fluid flow field by GeoDict. Concentration of chemical species at the inflow is constant, representing external fluid buffering. Changes/decrease in the concentration of chemical species occurs only due to vein growth. Growth of nuclei is limited either by transport of
3D time dependent thermo-fluid dynamic model of ground deformation at Campi Flegrei caldera
NASA Astrophysics Data System (ADS)
Castaldo, R.; Tizzani, P.; Manconi, A.; Manzo, M.; Pepe, S.; Pepe, A.; Lanari, R.
2012-04-01
In active volcanic areas deformation signals are generally characterized by non-linear spatial and temporal variations [Tizzani P. et al., 2007]. This behaviour has been revealed in the last two decades by the so-called advanced DInSAR processing algorithms, developed to analyze surface deformation phenomena [Berardino P. et al., 2002; Ferretti C. et al., 2001]. Notwithstanding, most of the inverse modelling attempts to characterize the evolution of the volcanic sources are based on the assumption that the Earth's crust behaves as a homogeneous linear elastic material. However, the behaviour of the upper lithosphere in thermally anomalous regions (as active volcanoes are) might be well described as a non-Newtonian fluid, where some of the material proprieties of the rocks (i.e., apparent viscosities) can change over time [Pinkerton H. et al., 1995]. In this context, we considered the thermal proprieties and mechanical heterogeneities of the upper crust in order to develop a new 3D time dependent thermo-fluid dynamic model of Campi Flegrei (CF) caldera, Southern Italy. More specifically, according to Tizzani P. et al. (2010), we integrated in a FEM environment geophysical information (gravimetric, seismic, and borehole data) available for the considered area and performed two FEM optimization procedures to constrain the 3D distribution of unknown physical parameters (temperature and viscosity distributions) that might help explaining the data observed at surface (geothermal wells and DInSAR measurements). First, we searched for the heat production, the volume source distribution and surface emissivity parameters providing the best-fit of the geothermal profiles data measured at six boreholes [Agip ESGE, 1986], by solving the Fourier heat equation over time (about 40 kys). The 3D thermal field resulting from this optimization was used to calculate the 3D brittle-ductile transition. This analysis revealed the presence of a ductile region, located beneath the centre of
User's manual for PELE3D: a computer code for three-dimensional incompressible fluid dynamics
McMaster, W H
1982-05-07
The PELE3D code is a three-dimensional semi-implicit Eulerian hydrodynamics computer program for the solution of incompressible fluid flow coupled to a structure. The fluid and coupling algorithms have been adapted from the previously developed two-dimensional code PELE-IC. The PELE3D code is written in both plane and cylindrical coordinates. The coupling algorithm is general enough to handle a variety of structural shapes. The free surface algorithm is able to accommodate a top surface and several independent bubbles. The code is in a developmental status since all the intended options have not been fully implemented and tested. Development of this code ended in 1980 upon termination of the contract with the Nuclear Regulatory Commission.
Anderson, Jeff R; Diaz, Orlando; Klucznik, Richard; Zhang, Y Jonathan; Britz, Gavin W; Grossman, Robert G; Lv, Nan; Huang, Qinghai; Karmonik, Christof
2014-01-01
A new concept of rapid 3D prototyping was implemented using cost-effective 3D printing for creating anatomically correct replica of cerebral aneurysms. With a dedicated flow loop set-up in a full body human MRI scanner, flow measurements were performed using 4D phase contrast magnetic resonance imaging to visualize and quantify intra-aneurysmal flow patterns. Ultrashort TE sequences were employed to obtain high-resolution 3D image data to visualize the lumen inside the plastic replica. In-vitro results were compared with retrospectively obtained in-vivo data and results from computational fluid dynamics simulations (CFD). Rapid prototyping of anatomically realistic 3D models may have future impact in treatment planning, design of image acquisition methods for MRI and angiographic systems and for the design and testing of advanced image post-processing technologies.
Schmitt, Vivien; Dufresne, Matthieu; Vazquez, Jose; Fischer, Martin; Morin, Antoine
2014-01-01
The aim of this study is to investigate the use of computational fluid dynamics (CFD) to predict the solid separation efficiency of a hydrodynamic separator. The numerical difficulty concerns the discretization of the geometry to simulate both the global behavior and the local phenomena that occur near the screen. In this context, a CFD multiscale approach was used: a global model (at the scale of the device) is used to observe the hydrodynamic behavior within the device; a local model (portion of the screen) is used to determine the local phenomena that occur near the screen. The Eulerian-Lagrangian approach was used to model the particle trajectories in both models. The global model shows the influence of the particles' characteristics on the trapping efficiency. A high density favors the sedimentation. In contrast, particles with small densities (1,040 kg/m(3)) are steered by the hydrodynamic behavior and can potentially be trapped by the separator. The use of the local model allows us to observe the particle trajectories near the screen. A comparison between two types of screens (perforated plate vs expanded metal) highlights the turbulent effects created by the shape of the screen.
Gallo, Diego; Gülan, Utku; Di Stefano, Antonietta; Ponzini, Raffaele; Lüthi, Beat; Holzner, Markus; Morbiducci, Umberto
2014-09-22
Parallel to the massive use of image-based computational hemodynamics to study the complex flow establishing in the human aorta, the need for suitable experimental techniques and ad hoc cases for the validation and benchmarking of numerical codes has grown more and more. Here we present a study where the 3D pulsatile flow in an anatomically realistic phantom of human ascending aorta is investigated both experimentally and computationally. The experimental study uses 3D particle tracking velocimetry (PTV) to characterize the flow field in vitro, while finite volume method is applied to numerically solve the governing equations of motion in the same domain, under the same conditions. Our findings show that there is an excellent agreement between computational and measured flow fields during the forward flow phase, while the agreement is poorer during the reverse flow phase. In conclusion, here we demonstrate that 3D PTV is very suitable for a detailed study of complex unsteady flows as in aorta and for validating computational models of aortic hemodynamics. In a future step, it will be possible to take advantage from the ability of 3D PTV to evaluate velocity fluctuations and, for this reason, to gain further knowledge on the process of transition to turbulence occurring in the thoracic aorta.
NASA Astrophysics Data System (ADS)
Chepyzhov, V. V.
2016-04-01
We study the limit as α\\to 0{+} of the long-time dynamics for various approximate α-models of a viscous incompressible fluid and their connection with the trajectory attractor of the exact 3D Navier-Stokes system. The α-models under consideration are divided into two classes depending on the orthogonality properties of the nonlinear terms of the equations generating every particular α-model. We show that the attractors of α-models of class I have stronger properties of attraction for their trajectories than the attractors of α-models of class II. We prove that for both classes the bounded families of trajectories of the α-models considered here converge in the corresponding weak topology to the trajectory attractor A_0 of the exact 3D Navier-Stokes system as time t tends to infinity. Furthermore, we establish that the trajectory attractor A_α of every α-model converges in the same topology to the attractor A_0 as α\\to 0{+}. We construct the minimal limits A\\min\\subseteqA_0 of the trajectory attractors A_α for all α-models as α\\to 0{+}. We prove that every such set A\\min is a compact connected component of the trajectory attractor A_0, and all the A\\min are strictly invariant under the action of the translation semigroup.Bibliography: 39 titles.
Chi, Albert; Curi, Sebastian; Clayton, Kevin; Luciano, David; Klauber, Kameron; Alexander-Katz, Alfredo; D'hers, Sebastian; Elman, Noel M
2014-08-01
Rapid Reconstitution Packages (RRPs) are portable platforms that integrate microfluidics for rapid reconstitution of lyophilized drugs. Rapid reconstitution of lyophilized drugs using standard vials and syringes is an error-prone process. RRPs were designed using computational fluid dynamics (CFD) techniques to optimize fluidic structures for rapid mixing and integrating physical properties of targeted drugs and diluents. Devices were manufactured using stereo lithography 3D printing for micrometer structural precision and rapid prototyping. Tissue plasminogen activator (tPA) was selected as the initial model drug to test the RRPs as it is unstable in solution. tPA is a thrombolytic drug, stored in lyophilized form, required in emergency settings for which rapid reconstitution is of critical importance. RRP performance and drug stability were evaluated by high-performance liquid chromatography (HPLC) to characterize release kinetics. In addition, enzyme-linked immunosorbent assays (ELISAs) were performed to test for drug activity after the RRPs were exposed to various controlled temperature conditions. Experimental results showed that RRPs provided effective reconstitution of tPA that strongly correlated with CFD results. Simulation and experimental results show that release kinetics can be adjusted by tuning the device structural dimensions and diluent drug physical parameters. The design of RRPs can be tailored for a number of applications by taking into account physical parameters of the active pharmaceutical ingredients (APIs), excipients, and diluents. RRPs are portable platforms that can be utilized for reconstitution of emergency drugs in time-critical therapies.
Tan, Germaine Xin Yi; Jamil, Muhammad; Tee, Nicole Gui Zhen; Zhong, Liang; Yap, Choon Hwai
2015-11-01
Recent animal studies have provided evidence that prenatal blood flow fluid mechanics may play a role in the pathogenesis of congenital cardiovascular malformations. To further these researches, it is important to have an imaging technique for small animal embryos with sufficient resolution to support computational fluid dynamics studies, and that is also non-invasive and non-destructive to allow for subject-specific, longitudinal studies. In the current study, we developed such a technique, based on ultrasound biomicroscopy scans on chick embryos. Our technique included a motion cancelation algorithm to negate embryonic body motion, a temporal averaging algorithm to differentiate blood spaces from tissue spaces, and 3D reconstruction of blood volumes in the embryo. The accuracy of the reconstructed models was validated with direct stereoscopic measurements. A computational fluid dynamics simulation was performed to model fluid flow in the generated construct of a Hamburger-Hamilton (HH) stage 27 embryo. Simulation results showed that there were divergent streamlines and a low shear region at the carotid duct, which may be linked to the carotid duct's eventual regression and disappearance by HH stage 34. We show that our technique has sufficient resolution to produce accurate geometries for computational fluid dynamics simulations to quantify embryonic cardiovascular fluid mechanics.
NASA Technical Reports Server (NTRS)
Bartels, Robert E.
2012-01-01
This paper presents the implementation of gust modeling capability in the CFD code FUN3D. The gust capability is verified by computing the response of an airfoil to a sharp edged gust. This result is compared with the theoretical result. The present simulations will be compared with other CFD gust simulations. This paper also serves as a users manual for FUN3D gust analyses using a variety of gust profiles. Finally, the development of an Auto-Regressive Moving-Average (ARMA) reduced order gust model using a gust with a Gaussian profile in the FUN3D code is presented. ARMA simulated results of a sequence of one-minus-cosine gusts is shown to compare well with the same gust profile computed with FUN3D. Proper Orthogonal Decomposition (POD) is combined with the ARMA modeling technique to predict the time varying pressure coefficient increment distribution due to a novel gust profile. The aeroelastic response of a pitch/plunge airfoil to a gust environment is computed with a reduced order model, and compared with a direct simulation of the system in the FUN3D code. The two results are found to agree very well.
Neidlin, Michael; Steinseifer, Ulrich; Kaufmann, Tim A S
2014-06-01
Neurological complication often occurs during cardiopulmonary bypass (CPB). One of the main causes is hypoperfusion of the cerebral tissue affected by the position of the cannula tip and diminished cerebral autoregulation (CA). Recently, a lumped parameter approach could describe the baroreflex, one of the main mechanisms of cerebral autoregulation, in a computational fluid dynamics (CFD) study of CPB. However, the cerebral blood flow (CBF) was overestimated and the physiological meaning of the variables and their impact on the model was unknown. In this study, we use a 0-D control circuit representation of the Baroreflex mechanism, to assess the parameters with respect to their physiological meaning and their influence on CBF. Afterwards the parameters are transferred to 3D-CFD and the static and dynamic behavior of cerebral autoregulation is investigated. The parameters of the baroreflex mechanism can reproduce normotensive, hypertensive and impaired autoregulation behavior. Further on, the proposed model can mimic the effects of anesthetic agents and other factors controlling dynamic CA. The CFD simulations deliver similar results of static and dynamic CBF as the 0-D control circuit. This study shows the feasibility of a multiscale 0-D/3-D approach to include patient-specific cerebral autoregulation into CFD studies. PMID:24746017
Schwall, James R.; Karim, Naeem U.; Thakkar, Jivan G.; Taylor, Creed; Schulz, Terry; Wright, Richard F.
2006-07-01
The AP1000 is an 1100 MWe advanced nuclear power plant that uses passive safety features to enhance plant safety and to provide significant and measurable improvements in plant simplification, reliability, investment protection and plant costs. The AP1000 received final design approval from the US-NRC in 2004. The AP1000 design is based on the AP600 design that received final design approval in 1999. Wherever possible, the AP1000 plant configuration and layout was kept the same as AP600 to take advantage of the maturity of the design and to minimize new design efforts. As a result, the two-loop configuration was maintained for AP1000, and the containment vessel diameter was kept the same. It was determined that this significant power up-rate was well within the capability of the passive safety features, and that the safety margins for AP1000 were greater than those of operating PWRs. A key feature of the passive core cooling system is the passive residual heat removal heat exchanger (PRHR HX) that provides decay heat removal for postulated LOCA and non-LOCA events. The PRHR HX is a C-tube heat exchanger located in the in-containment refueling water storage tank (IRWST) above the core promoting natural circulation heat removal between the reactor cooling system and the tank. Component testing was performed for the AP600 PRHR HX to determine the heat transfer characteristics and to develop correlations to be used for the AP1000 safety analysis codes. The data from these tests were confirmed by subsequent integral tests at three separate facilities including the ROSA facility in Japan. Owing to the importance of this component, an independent analysis has been performed using the ATHOS-based computational fluid dynamics computer code PRHRCFD. Two separate models of the PRHR HX and IRWST have been developed representing the ROSA test geometry and the AP1000 plant geometry. Confirmation of the ROSA test results were used to validate PRHRCFD, and the AP1000 plant model
Mori, Daisuke; Yamaguchi, Takami
2002-06-01
An idealized CFD model and a realistic one were used to investigate the effect of the 3-D distortion of the aortic arch on the blood flow and its pathophysiological significance with respect to the pathogenesis of the aortic aneurysm. From the results of the flow simulations, the distortion of the centerline of the pipe was shown to affect significantly the flow structure. A right-handed vortex at the descending arch, and a left-handed one at the end of the arch tended to develop in the realistic model. But the secondary flow did not become a single helix. The top of the arch was the region where complex spatial and temporal WSS distributed. It was also observed that the direction of WSS had a significant circumferential component at the top of the arch.
NASA Astrophysics Data System (ADS)
Meisenheimer, D.; Brueck, C. L.; Wildenschild, D.
2015-12-01
X-ray microtomography imaging of fluid-fluid interfaces in three-dimensional porous media allows for the testing of thermodynamically derived predictions that seek a unique relationship between capillary pressure, fluid saturation, and specific interfacial area (Pc-Sw-Anw). Previous experimental studies sought to test this functional dependence under quasi-equilibrium conditions (assumed static on the imaging time-scale); however, applying predictive models developed under static conditions for dynamic scenarios can lead to substantial flaws in predicted outcomes. Theory and models developed using dynamic data can be verified using fast x-ray microtomography which allows for the unprecedented measurement of developing interfacial areas, curvatures, and trapping behaviors of fluid phases in three-dimensional systems. We will present results of drainage and imbibition experiments of air and water within a mixture of glass beads. The experiments were performed under both quasi-equilibrium and dynamic conditions at the Advanced Photon Source (APS) at Argonne National Laboratory. Fast x-ray microtomography was achieved by utilizing the high brilliance of the x-ray beam at the APS under pink-beam conditions where the white beam is modified with a 4 mm Al absorber and a 0.8 mrad Pt-coated mirror to eliminate low and high-energy photons, respectively. We present a comparison of the results from the quasi-equilibrium and dynamic experiments in an effort to determine if the Pc-Sw-Anw relationship is comparable under either experimental condition and to add to the discussion on whether the Pc-Sw-Anw relationship is unique as hypothesized by existing theory.
TEMPEST/N33.5. Computational Fluid Dynamics Package For Incompressible, 3D, Time Dependent Pro
Trent, Dr.D.S.; Eyler, Dr.L.L.
1991-04-01
TEMPESTN33.5 provides numerical solutions to general incompressible flow problems with coupled heat transfer in fluids and solids. Turbulence is created with a k-e model and gas, liquid or solid constituents may be included with the bulk flow. Problems may be modeled in Cartesian or cylindrical coordinates. Limitations include incompressible flow, Boussinesq approximation, and passive constituents. No direct steady state solution is available; steady state is obtained as the limit of a transient.
Static & Dynamic Response of 3D Solids
1996-07-15
NIKE3D is a large deformations 3D finite element code used to obtain the resulting displacements and stresses from multi-body static and dynamic structural thermo-mechanics problems with sliding interfaces. Many nonlinear and temperature dependent constitutive models are available.
3D dynamic roadmapping for abdominal catheterizations.
Bender, Frederik; Groher, Martin; Khamene, Ali; Wein, Wolfgang; Heibel, Tim Hauke; Navab, Nassir
2008-01-01
Despite rapid advances in interventional imaging, the navigation of a guide wire through abdominal vasculature remains, not only for novice radiologists, a difficult task. Since this navigation is mostly based on 2D fluoroscopic image sequences from one view, the process is slowed down significantly due to missing depth information and patient motion. We propose a novel approach for 3D dynamic roadmapping in deformable regions by predicting the location of the guide wire tip in a 3D vessel model from the tip's 2D location, respiratory motion analysis, and view geometry. In a first step, the method compensates for the apparent respiratory motion in 2D space before backprojecting the 2D guide wire tip into three dimensional space, using a given projection matrix. To countervail the error connected to the projection parameters and the motion compensation, as well as the ambiguity caused by vessel deformation, we establish a statistical framework, which computes a reliable estimate of the guide wire tip location within the 3D vessel model. With this 2D-to-3D transfer, the navigation can be performed from arbitrary viewing angles, disconnected from the static perspective view of the fluoroscopic sequence. Tests on a realistic breathing phantom and on synthetic data with a known ground truth clearly reveal the superiority of our approach compared to naive methods for 3D roadmapping. The concepts and information presented in this paper are based on research and are not commercially available. PMID:18982662
INCORPORATING DYNAMIC 3D SIMULATION INTO PRA
Steven R Prescott; Curtis Smith
2011-07-01
provide superior results and insights. We also couple the state model with the dynamic 3D simulation analysis representing events (such as flooding) to determine which (if any) components fail. Not only does the simulation take into account any failed items from the state model, but any failures caused by the simulation are incorporated back into the state model and factored into the overall results. Using this method we incorporate accurate 3D simulation results, eliminate static-based PRA issues, and have time ordered failure information.
A dynamic 3D foot reconstruction system.
Thabet, Ali K; Trucco, Emanuele; Salvi, Joaquim; Wang, Weijie; Abboud, Rami J
2011-01-01
Foot problems are varied and range from simple disorders through to complex diseases and joint deformities. Wherever possible, the use of insoles, or orthoses, is preferred over surgery. Current insole design techniques are based on static measurements of the foot, despite the fact that orthoses are prevalently used in dynamic conditions while walking or running. This paper presents the design and implementation of a structured-light prototype system providing dense three dimensional (3D) measurements of the foot in motion, and its use to show that foot measurements in dynamic conditions differ significantly from their static counterparts. The input to the system is a video sequence of a foot during a single step; the output is a 3D reconstruction of the plantar surface of the foot for each frame of the input. Engineering and clinical tests were carried out for the validation of the system. The accuracy of the system was found to be 0.34 mm with planar test objects. In tests with real feet, the system proved repeatable, with reconstruction differences between trials one week apart averaging 2.44 mm (static case) and 2.81 mm (dynamic case). Furthermore, a study was performed to compare the effective length of the foot between static and dynamic reconstructions using the 4D system. Results showed an average increase of 9 mm for the dynamic case. This increase is substantial for orthotics design, cannot be captured by a static system, and its subject-specific measurement is crucial for the design of effective foot orthoses.
Dynamics of 3D isolated thermal filaments
NASA Astrophysics Data System (ADS)
Walkden, N. R.; Easy, L.; Militello, F.; Omotani, J. T.
2016-11-01
Simulations have been carried out to establish how electron thermal physics, introduced in the form of a dynamic electron temperature, affects isolated filament motion and dynamics in 3D. It is found that thermal effects impact filament motion in two major ways when the pressure perturbation within the filament is supported primarily through a temperature increase as opposed to density: they lead to a strong increase in filament propagation in the bi-normal direction and a significant decrease in net radial propagation. Both effects arise from the temperature dependence of the sheath current which leads to a non-uniform floating potential, with the latter effect supplemented by faster pressure loss. The reduction in radial velocity can only occur when the filament cross-section loses angular symmetry. The behaviour is observed across different filament sizes and suggests that filaments with much larger temperature perturbations than density perturbations are more strongly confined to the near SOL region.
Dynamic phototuning of 3D hydrogel stiffness
Stowers, Ryan S.; Allen, Shane C.; Suggs, Laura J.
2015-01-01
Hydrogels are widely used as in vitro culture models to mimic 3D cellular microenvironments. The stiffness of the extracellular matrix is known to influence cell phenotype, inspiring work toward unraveling the role of stiffness on cell behavior using hydrogels. However, in many biological processes such as embryonic development, wound healing, and tumorigenesis, the microenvironment is highly dynamic, leading to changes in matrix stiffness over a broad range of timescales. To recapitulate dynamic microenvironments, a hydrogel with temporally tunable stiffness is needed. Here, we present a system in which alginate gel stiffness can be temporally modulated by light-triggered release of calcium or a chelator from liposomes. Others have shown softening via photodegradation or stiffening via secondary cross-linking; however, our system is capable of both dynamic stiffening and softening. Dynamic modulation of stiffness can be induced at least 14 d after gelation and can be spatially controlled to produce gradients and patterns. We use this system to investigate the regulation of fibroblast morphology by stiffness in both nondegradable gels and gels with degradable elements. Interestingly, stiffening inhibits fibroblast spreading through either mesenchymal or amoeboid migration modes. We demonstrate this technology can be translated in vivo by using deeply penetrating near-infrared light for transdermal stiffness modulation, enabling external control of gel stiffness. Temporal modulation of hydrogel stiffness is a powerful tool that will enable investigation of the role that dynamic microenvironments play in biological processes both in vitro and in well-controlled in vivo experiments. PMID:25646417
An annotation system for 3D fluid flow visualization
NASA Technical Reports Server (NTRS)
Loughlin, Maria M.; Hughes, John F.
1995-01-01
Annotation is a key activity of data analysis. However, current systems for data analysis focus almost exclusively on visualization. We propose a system which integrates annotations into a visualization system. Annotations are embedded in 3D data space, using the Post-it metaphor. This embedding allows contextual-based information storage and retrieval, and facilitates information sharing in collaborative environments. We provide a traditional database filter and a Magic Lens filter to create specialized views of the data. The system has been customized for fluid flow applications, with features which allow users to store parameters of visualization tools and sketch 3D volumes.
Fast 3D fluid registration of brain magnetic resonance images
NASA Astrophysics Data System (ADS)
Leporé, Natasha; Chou, Yi-Yu; Lopez, Oscar L.; Aizenstein, Howard J.; Becker, James T.; Toga, Arthur W.; Thompson, Paul M.
2008-03-01
Fluid registration is widely used in medical imaging to track anatomical changes, to correct image distortions, and to integrate multi-modality data. Fluid mappings guarantee that the template image deforms smoothly into the target, without tearing or folding, even when large deformations are required for accurate matching. Here we implemented an intensity-based fluid registration algorithm, accelerated by using a filter designed by Bro-Nielsen and Gramkow. We validated the algorithm on 2D and 3D geometric phantoms using the mean square difference between the final registered image and target as a measure of the accuracy of the registration. In tests on phantom images with different levels of overlap, varying amounts of Gaussian noise, and different intensity gradients, the fluid method outperformed a more commonly used elastic registration method, both in terms of accuracy and in avoiding topological errors during deformation. We also studied the effect of varying the viscosity coefficients in the viscous fluid equation, to optimize registration accuracy. Finally, we applied the fluid registration algorithm to a dataset of 2D binary corpus callosum images and 3D volumetric brain MRIs from 14 healthy individuals to assess its accuracy and robustness.
Complex flow dynamics around 3D microbot prototypes.
Martínez-Aranda, Sergio; Galindo-Rosales, Francisco J; Campo-Deaño, Laura
2016-02-28
A new experimental setup for the study of the complex flow dynamics around 3D microbot prototypes in a straight microchannel has been developed and assessed. The ultimate aim of this work is focused on the analysis of the morphology of different microbot prototypes to get a better insight into their efficiency when they swim through the main conduits of the human circulatory system. The setup consists of a fused silica straight microchannel with a 3D microbot prototype fastened in the center of the channel cross-section by an extremely thin support. Four different prototypes were considered: a cube, a sphere and two ellipsoids with aspect ratios of 1 : 2 and 1 : 4, respectively. Flow visualization and micro-particle image velocimetry (μPIV) measurements were performed using Newtonian and viscoelastic blood analogue fluids. An efficiency parameter, ℑ, to discriminate the prototypes in terms of flow disturbance has been proposed.
ICEd-ALE Treatment of 3-D Fluid Flow.
1999-09-13
Version: 00 SALE3D calculates three-dimensional fluid flow at all speeds, from the incompressible limit to highly supersonic. An implicit treatment of the pressure calculation similar to that in the Implicit Continuous-fluid Eulerian (ICE) technique provides this flow speed flexibility. In addition, the computing mesh may move with the fluid in a typical Lagrangian fashion, be held in an Eulerian manner, or move in some arbitrarily specified way to provide a continuous rezoning capability. This latitudemore » results from use of an Arbitrary Lagrangian-Eulerian (ALE) treatment of the mesh. The partial differential equations solved are the Navier-Stokes equations and the mass and internal energy equations. The fluid pressure is determined from an equation of state and supplemented with an artificial viscous pressure for the computation of shock waves. The computing mesh consists of a three-dimensional network of arbitrarily shaped, six-sided deformable cells, and a variety of user-selectable boundary conditions are provided in the program.« less
3D-dynamic representation of DNA sequences.
Wąż, Piotr; Bielińska-Wąż, Dorota
2014-03-01
A new 3D graphical representation of DNA sequences is introduced. This representation is called 3D-dynamic representation. It is a generalization of the 2D-dynamic dynamic representation. The sequences are represented by sets of "material points" in the 3D space. The resulting 3D-dynamic graphs are treated as rigid bodies. The descriptors characterizing the graphs are analogous to the ones used in the classical dynamics. The classification diagrams derived from this representation are presented and discussed. Due to the third dimension, "the history of the graph" can be recognized graphically because the 3D-dynamic graph does not overlap with itself. Specific parts of the graphs correspond to specific parts of the sequence. This feature is essential for graphical comparisons of the sequences. Numerically, both 2D and 3D approaches are of high quality. In particular, a difference in a single base between two sequences can be identified and correctly described (one can identify which base) by both 2D and 3D methods. PMID:24567158
3D joint dynamics analysis of healthy children's gait.
Samson, William; Desroches, Guillaume; Cheze, Laurence; Dumas, Raphaël
2009-11-13
The 3D joint moments and 2D joint powers have been largely explored in the literature of healthy children's gait, in particular to compare them with pathologic subjects' gait. However, no study reported on 3D joint power in children which could be due to the difficulties in interpreting the results. Recently, the analysis of the 3D angle between the joint moment and the joint angular velocity vectors has been proposed in order to help 3D joint power interpretation. Our hypothesis is that this 3D angle may help in characterizing the level of gait maturation. The present study explores 3D joint moments, 3D joint power and the proposed 3D angle for both children's and adults' gaits to highlight differences in the strategies used. The results seem to confirm that children have an alternative strategy of mainly ankle stabilization and hip propulsion compared to the adults' strategy of mainly ankle resistance and propulsion and hip stabilization. In the future, the same 3D angle analysis should be applied to different age groups for better describing the evolution of the 3D joint dynamic strategies during the growth.
Dynamic 3D Visualization of Vocal Tract Shaping During Speech
Zhu, Yinghua; Kim, Yoon-Chul; Proctor, Michael I.; Narayanan, Shrikanth S.; Nayak, Krishna S.
2014-01-01
Noninvasive imaging is widely used in speech research as a means to investigate the shaping and dynamics of the vocal tract during speech production. 3D dynamic MRI would be a major advance, as it would provide 3D dynamic visualization of the entire vocal tract. We present a novel method for the creation of 3D dynamic movies of vocal tract shaping based on the acquisition of 2D dynamic data from parallel slices and temporal alignment of the image sequences using audio information. Multiple sagittal 2D real-time movies with synchronized audio recordings are acquired for English vowel-consonant-vowel stimuli /ala/, /aɹa/, /asa/ and /aʃa/. Audio data are aligned using mel-frequency cepstral coefficients (MFCC) extracted from windowed intervals of the speech signal. Sagittal image sequences acquired from all slices are then aligned using dynamic time warping (DTW). The aligned image sequences enable dynamic 3D visualization by creating synthesized movies of the moving airway in the coronal planes, visualizing desired tissue surfaces and tube-shaped vocal tract airway after manual segmentation of targeted articulators and smoothing. The resulting volumes allow for dynamic 3D visualization of salient aspects of lingual articulation, including the formation of tongue grooves and sublingual cavities, with a temporal resolution of 78 ms. PMID:23204279
Dynamic contrast-enhanced 3D photoacoustic imaging
NASA Astrophysics Data System (ADS)
Wong, Philip; Kosik, Ivan; Carson, Jeffrey J. L.
2013-03-01
Photoacoustic imaging (PAI) is a hybrid imaging modality that integrates the strengths from both optical imaging and acoustic imaging while simultaneously overcoming many of their respective weaknesses. In previous work, we reported on a real-time 3D PAI system comprised of a 32-element hemispherical array of transducers. Using the system, we demonstrated the ability to capture photoacoustic data, reconstruct a 3D photoacoustic image, and display select slices of the 3D image every 1.4 s, where each 3D image resulted from a single laser pulse. The present study aimed to exploit the rapid imaging speed of an upgraded 3D PAI system by evaluating its ability to perform dynamic contrast-enhanced imaging. The contrast dynamics can provide rich datasets that contain insight into perfusion, pharmacokinetics and physiology. We captured a series of 3D PA images of a flow phantom before and during injection of piglet and rabbit blood. Principal component analysis was utilized to classify the data according to its spatiotemporal information. The results suggested that this technique can be used to separate a sequence of 3D PA images into a series of images representative of main features according to spatiotemporal flow dynamics.
An Evaluative Review of Simulated Dynamic Smart 3d Objects
NASA Astrophysics Data System (ADS)
Romeijn, H.; Sheth, F.; Pettit, C. J.
2012-07-01
Three-dimensional (3D) modelling of plants can be an asset for creating agricultural based visualisation products. The continuum of 3D plants models ranges from static to dynamic objects, also known as smart 3D objects. There is an increasing requirement for smarter simulated 3D objects that are attributed mathematically and/or from biological inputs. A systematic approach to plant simulation offers significant advantages to applications in agricultural research, particularly in simulating plant behaviour and the influences of external environmental factors. This approach of 3D plant object visualisation is primarily evident from the visualisation of plants using photographed billboarded images, to more advanced procedural models that come closer to simulating realistic virtual plants. However, few programs model physical reactions of plants to external factors and even fewer are able to grow plants based on mathematical and/or biological parameters. In this paper, we undertake an evaluation of plant-based object simulation programs currently available, with a focus upon the components and techniques involved in producing these objects. Through an analytical review process we consider the strengths and weaknesses of several program packages, the features and use of these programs and the possible opportunities in deploying these for creating smart 3D plant-based objects to support agricultural research and natural resource management. In creating smart 3D objects the model needs to be informed by both plant physiology and phenology. Expert knowledge will frame the parameters and procedures that will attribute the object and allow the simulation of dynamic virtual plants. Ultimately, biologically smart 3D virtual plants that react to changes within an environment could be an effective medium to visually represent landscapes and communicate land management scenarios and practices to planners and decision-makers.
Numerical simulations and vorticity dynamics of self-propelled swimming of 3D bionic fish
NASA Astrophysics Data System (ADS)
Xin, ZhiQiang; Wu, ChuiJie
2012-02-01
Numerical simulations and the control of self-propelled swimming of three-dimensional bionic fish in a viscous flow and the mechanism of fish swimming are carried out in this study, with a 3D computational fluid dynamics package, which includes the immersed boundary method and the volume of fluid method, the adaptive multi-grid finite volume method, and the control strategy of fish swimming. Firstly, the mechanism of 3D fish swimming was studied and the vorticity dynamics root was traced to the moving body surface by using the boundary vorticity-flux theory. With the change of swimming speed, the contributions of the fish body and caudal fin to thrust are analyzed quantitatively. The relationship between vortex structures of fish swimming and the forces exerted on the fish body are also given in this paper. Finally, the 3D wake structure of self-propelled swimming of 3D bionic fish is presented. The in-depth analysis of the 3D vortex structure in the role of 3D biomimetic fish swimming is also performed.
3D two-fluid simulations of turbulence in LAPD
NASA Astrophysics Data System (ADS)
Fisher, Dustin M.
The Large Plasma Device (LAPD) is modeled using a modified version of the 3D Global Braginskii Solver code (GBS) for a nominal Helium plasma. The unbiased low-flow regime is explored in simulations where there is an intrinsic E x B rotation of the plasma. In the simulations this rotation is caused primarily by sheath effects with the Reynolds stress and J x B torque due to a cross-field Pederson conductivity having little effect. Explicit biasing simulations are also explored for the first time where the intrinsic rotation of the plasma is modified through boundary conditions that mimic the biasable limiter used in LAPD. Comparisons to experimental measurements in the unbiased case show strong qualitative agreement with the data, particularly the radial dependence of the density fluctuations, cross-correlation lengths, radial flux dependence outside of the cathode edge, and camera imagery. Kelvin Helmholtz (KH) turbulence at relatively large scales is the dominant driver of cross-field transport in these simulations with smaller-scale drift waves and sheath modes playing a secondary role. Plasma holes and blobs arising from KH vortices are consistent with the scale sizes and overall appearance of those in LAPD camera images. The addition of ion-neutral collisions in the unbiased simulations at previously theorized values reduces the radial particle flux due to a modest stabilizing contribution of the collisions on the KH-modes driving the turbulent transport. In the biased runs the ion-neutral collisions have a much smaller effect due to the modification of the potential from sheath terms. In biasing the plasma to increase the intrinsic rotation, simulations show the emergence of a nonlinearly saturated coherent mode of order m = 6. In addition, the plasma inside of the cathode edge becomes quiescent due to the strong influence of the wall bias in setting up the equilibrium plasma potential. Biasing in the direction opposite to the intrinsic flow reduces the
3-D structure and dynamics of microtubule self-organization
NASA Astrophysics Data System (ADS)
Wang, Jing; Ou-Yang, H. Daniel
2008-03-01
Laser scanning confocal microscopy was used to study the dynamics of 3D assemblies spontaneously formed in microtubule (MT) solutions. Microtubule solutions prepared by mixing and incubating tubulin in the presence of GTP and Oregon Green conjugated taxol in PM buffer were placed in long, sub-millimeter thin glass cells by the capillary action. Within 24 hours, starting with a uniform distribution, microtubules were found to be gradually separated into a few large ``buckled'' bundles along the long direction, and in the middle plane, of the sample cell. A well-defined wavelength of the buckling sinusoids was around 510 μm. The cross section of these round bundles was approximately 40 μm in diameter and the lengths were several centimeters. Detailed analysis of the 3-D image within the bundles revealed that each bundle seemed to consist of loosely packed MTs. It appeared that MTs were phase separated resulting from attractive interactions between charged MT fibers. The ``buckling'' behavior could be the result of geometrical constraints of the repulsive cell walls and the repulsive interaction between bundles. Detailed 3-D observations of the dynamic evolution of MT assembly could provide insight to the mechanisms of cellular MT organization and phase separation of charged colloidal rods.
Dynamic 3D computed tomography scanner for vascular imaging
NASA Astrophysics Data System (ADS)
Lee, Mark K.; Holdsworth, David W.; Fenster, Aaron
2000-04-01
A 3D dynamic computed-tomography (CT) scanner was developed for imaging objects undergoing periodic motion. The scanner system has high spatial and sufficient temporal resolution to produce quantitative tomographic/volume images of objects such as excised arterial samples perfused under physiological pressure conditions and enables the measurements of the local dynamic elastic modulus (Edyn) of the arteries in the axial and longitudinal directions. The system was comprised of a high resolution modified x-ray image intensifier (XRII) based computed tomographic system and a computer-controlled cardiac flow simulator. A standard NTSC CCD camera with a macro lens was coupled to the electro-optically zoomed XRII to acquire dynamic volumetric images. Through prospective cardiac gating and computer synchronized control, a time-resolved sequence of 20 mm thick high resolution volume images of porcine aortic specimens during one simulated cardiac cycle were obtained. Performance evaluation of the scanners illustrated that tomographic images can be obtained with resolution as high as 3.2 mm-1 with only a 9% decrease in the resolution for objects moving at velocities of 1 cm/s in 2D mode and static spatial resolution of 3.55 mm-1 with only a 14% decrease in the resolution in 3D mode for objects moving at a velocity of 10 cm/s. Application of the system for imaging of intact excised arterial specimens under simulated physiological flow/pressure conditions enabled measurements of the Edyn of the arteries with a precision of +/- kPa for the 3D scanner. Evaluation of the Edyn in the axial and longitudinal direction produced values of 428 +/- 35 kPa and 728 +/- 71 kPa, demonstrating the isotropic and homogeneous viscoelastic nature of the vascular specimens. These values obtained from the Dynamic CT systems were not statistically different (p less than 0.05) from the values obtained by standard uniaxial tensile testing and volumetric measurements.
Fluid and cell behaviors along a 3D printed alginate/gelatin/fibrin channel.
Xu, Yufan; Wang, Xiaohong
2015-08-01
Three-dimensional (3D) cell manipulation is available with the integration of microfluidic technology and rapid prototyping techniques. High-Fidelity (Hi-Fi) constructs hold enormous therapeutic potential for organ manufacturing and regenerative medicine. In the present paper we introduced a quasi-three-dimensional (Q3D) model with parallel biocompatible alginate/gelatin/fibrin hurdles. The behaviors of fluids and cells along the microfluidic channels with various widths were studied. Cells inside the newly designed microfluidic channels attached and grew well. Morphological changes of adipose-derived stem cells (ADSCs) in both two-dimensional (2D) and 3D milieu were found on the printed constructs. Endothelialization occurred with the co-cultures of ADSCs and hepatocytes. This study provides insights into the interactions among fluids, cells and biomaterials, the behaviors of fluids and cells along the microfluidic channels, and the applications of Q3D techniques.
3D hybrid simulations with gyrokinetic particle ions and fluid electrons
Belova, E.V.; Park, W.; Fu, G.Y.; Strauss, H.R.; Sugiyama, L.E.
1998-12-31
The previous hybrid MHD/particle model (MH3D-K code) represented energetic ions as gyrokinetic (or drift-kinetic) particles coupled to MHD equations using the pressure or current coupling scheme. A small energetic to bulk ion density ratio was assumed, n{sub h}/n{sub b} {much_lt} 1, allowing the neglect of the energetic ion perpendicular inertia in the momentum equation and the use of MHD Ohm`s law E = {minus}v{sub b} {times} B. A generalization of this model in which all ions are treated as gyrokinetic/drift-kinetic particles and fluid description is used for the electron dynamics is considered in this paper.
GPU-Based Visualization of 3D Fluid Interfaces using Level Set Methods
NASA Astrophysics Data System (ADS)
Kadlec, B. J.
2009-12-01
We model a simple 3D fluid-interface problem using the level set method and visualize the interface as a dynamic surface. Level set methods allow implicit handling of complex topologies deformed by evolutions where sharp changes and cusps are present without destroying the representation. We present a highly optimized visualization and computation algorithm that is implemented in CUDA to run on the NVIDIA GeForce 295 GTX. CUDA is a general purpose parallel computing architecture that allows the NVIDIA GPU to be treated like a data parallel supercomputer in order to solve many computational problems in a fraction of the time required on a CPU. CUDA is compared to the new OpenCL™ (Open Computing Language), which is designed to run on heterogeneous computing environments but does not take advantage of low-level features in NVIDIA hardware that provide significant speedups. Therefore, our technique is implemented using CUDA and results are compared to a single CPU implementation to show the benefits of using the GPU and CUDA for visualizing fluid-interface problems. We solve a 1024^3 problem and experience significant speedup using the NVIDIA GeForce 295 GTX. Implementation details for mapping the problem to the GPU architecture are described as well as discussion on porting the technique to heterogeneous devices (AMD, Intel, IBM) using OpenCL. The results present a new interactive system for computing and visualizing the evolution of fluid interface problems on the GPU.
Fluid Dynamics of Bottle Filling
NASA Astrophysics Data System (ADS)
McGough, Patrick; Gao, Haijing; Appathurai, Santosh; Basaran, Osman
2011-11-01
Filling of bottles is a widely practiced operation in a large number of industries. Well known examples include filling of ``large'' bottles with shampoos and cleaners in the household products and beauty care industries and filling of ``small'' bottles in the pharmaceutical industry. Some bottle filling operations have recently drawn much attention from the fluid mechanics community because of the occurrence of a multitude of complex flow regimes, transitions, and instabilities such as mounding and coiling that occur as a bottle is filled with a fluid. In this talk, we present a primarily computational study of the fluid dynamical challenges that can arise during the rapid filling of bottles. Given the diversity of fluids used in filling applications, we consider four representative classes of fluids that exhibit Newtonian, shear-thinning, viscoelastic, and yield-stress rheologies. The equations governing the dynamics of bottle filling are solved either in their full 3D but axisymmetric form or using the slender-jet approximation.
Dynamical Systems Analysis of Fully 3D Ocean Features
NASA Astrophysics Data System (ADS)
Pratt, L. J.
2011-12-01
Dynamical systems analysis of transport and stirring processes has been developed most thoroughly for 2D flow fields. The calculation of manifolds, turnstile lobes, transport barriers, etc. based on observations of the ocean is most often conducted near the sea surface, whereas analyses at depth, usually carried out with model output, is normally confined to constant-z surfaces. At the meoscale and larger, ocean flows are quasi 2D, but smaller scale (submesoscale) motions, including mixed layer phenomena with significant vertical velocity, may be predominantly 3D. The zoology of hyperbolic trajectories becomes richer in such cases and their attendant manifolds are much more difficult to calculate. I will describe some of the basic geometrical features and corresponding Lagrangian Coherent Features expected to arise in upper ocean fronts, eddies, and Langmuir circulations. Traditional GFD models such as the rotating can flow may capture the important generic features. The dynamical systems approach is most helpful when these features are coherent and persistent and the implications and difficulties for this requirement in fully 3D flows will also be discussed.
Dynamic deformable models for 3D MRI heart segmentation
NASA Astrophysics Data System (ADS)
Zhukov, Leonid; Bao, Zhaosheng; Gusikov, Igor; Wood, John; Breen, David E.
2002-05-01
Automated or semiautomated segmentation of medical images decreases interstudy variation, observer bias, and postprocessing time as well as providing clincally-relevant quantitative data. In this paper we present a new dynamic deformable modeling approach to 3D segmentation. It utilizes recently developed dynamic remeshing techniques and curvature estimation methods to produce high-quality meshes. The approach has been implemented in an interactive environment that allows a user to specify an initial model and identify key features in the data. These features act as hard constraints that the model must not pass through as it deforms. We have employed the method to perform semi-automatic segmentation of heart structures from cine MRI data.
NASA Astrophysics Data System (ADS)
Vucinic, Dean; Deen, Danny; Oanta, Emil; Batarilo, Zvonimir; Lacor, Chris
This paper focuses on visualization and manipulation of graphical content in distributed network environments. The developed graphical middleware and 3D desktop prototypes were specialized for situational awareness. This research was done in the LArge Scale COllaborative decision support Technology (LASCOT) project, which explored and combined software technologies to support human-centred decision support system for crisis management (earthquake, tsunami, flooding, airplane or oil-tanker incidents, chemical, radio-active or other pollutants spreading, etc.). The performed state-of-the-art review did not identify any publicly available large scale distributed application of this kind. Existing proprietary solutions rely on the conventional technologies and 2D representations. Our challenge was to apply the "latest" available technologies, such Java3D, X3D and SOAP, compatible with average computer graphics hardware. The selected technologies are integrated and we demonstrate: the flow of data, which originates from heterogeneous data sources; interoperability across different operating systems and 3D visual representations to enhance the end-users interactions.
3D Dynamic Earthquake Fracture Simulation (Test Case)
NASA Astrophysics Data System (ADS)
Korkusuz Öztürk, Yasemin; Meral Özel, Nurcan; Ando, Ryosuke
2016-04-01
A 3D dynamic earthquake fracture simulation is being developed for the fault structures which are non-planar to understand heterogeneous stress states in the Marmara Sea. Locating in a seismic gap, a large earthquake is expected in the center of the Sea of Marmara. Concerning the fact that more than 14 million inhabitants of İstanbul, located very closely to the Marmara Sea, the importance of the analysis of the Central Marmara Sea is extremely high. A few 3D dynamic earthquake fracture studies have been already done in the Sea of Marmara for pure right lateral strike-slip stress regimes (Oglesby and Mai, 2012; Aochi and Ulrich, 2015). In this study, a 3D dynamic earthquake fracture model with heterogeneous stress patches from the TPV5, a SCEC code validation case, is adapted. In this test model, the fault and the ground surfaces are gridded by a scalene triangulation technique using GMSH program. For a grid size changing between 0.616 km and 1.050 km the number of elements for the fault surface is 1984 and for the ground surface is 1216. When these results are compared with Kaneko's results for TPV5 from SPECFEM3D, reliable findings could be observed for the first 6.5 seconds (stations on the fault) although a stability problem is encountered after this time threshold. To solve this problem grid sizes are made smaller, so the number of elements increase 7986 for the fault surface and 4867 for the ground surface. On the other hand, computational problems arise in that case, since the computation time is directly proportional to the number of total elements and the required memory also increases with the square of that. Therefore, it is expected that this method can be adapted for less coarse grid cases, regarding the main difficulty coming from the necessity of an effective supercomputer and run time limitations. The main objective of this research is to obtain 3D dynamic earthquake rupture scenarios, concerning not only planar and non-planar faults but also
Modeling tree crown dynamics with 3D partial differential equations.
Beyer, Robert; Letort, Véronique; Cournède, Paul-Henry
2014-01-01
We characterize a tree's spatial foliage distribution by the local leaf area density. Considering this spatially continuous variable allows to describe the spatiotemporal evolution of the tree crown by means of 3D partial differential equations. These offer a framework to rigorously take locally and adaptively acting effects into account, notably the growth toward light. Biomass production through photosynthesis and the allocation to foliage and wood are readily included in this model framework. The system of equations stands out due to its inherent dynamic property of self-organization and spontaneous adaptation, generating complex behavior from even only a few parameters. The density-based approach yields spatially structured tree crowns without relying on detailed geometry. We present the methodological fundamentals of such a modeling approach and discuss further prospects and applications. PMID:25101095
Modeling tree crown dynamics with 3D partial differential equations.
Beyer, Robert; Letort, Véronique; Cournède, Paul-Henry
2014-01-01
We characterize a tree's spatial foliage distribution by the local leaf area density. Considering this spatially continuous variable allows to describe the spatiotemporal evolution of the tree crown by means of 3D partial differential equations. These offer a framework to rigorously take locally and adaptively acting effects into account, notably the growth toward light. Biomass production through photosynthesis and the allocation to foliage and wood are readily included in this model framework. The system of equations stands out due to its inherent dynamic property of self-organization and spontaneous adaptation, generating complex behavior from even only a few parameters. The density-based approach yields spatially structured tree crowns without relying on detailed geometry. We present the methodological fundamentals of such a modeling approach and discuss further prospects and applications.
Image enhancement and segmentation of fluid-filled structures in 3D ultrasound images
NASA Astrophysics Data System (ADS)
Chalana, Vikram; Dudycha, Stephen; McMorrow, Gerald
2003-05-01
Segmentation of fluid-filled structures, such as the urinary bladder, from three-dimensional ultrasound images is necessary for measuring their volume. This paper describes a system for image enhancement, segmentation and volume measurement of fluid-filled structures on 3D ultrasound images. The system was applied for the measurement of urinary bladder volume. Results show an average error of less than 10% in the estimation of the total bladder volume.
Analysis and dynamic 3D visualization of cerebral blood flow combining 3D and 4D MR image sequences
NASA Astrophysics Data System (ADS)
Forkert, Nils Daniel; Säring, Dennis; Fiehler, Jens; Illies, Till; Möller, Dietmar; Handels, Heinz
2009-02-01
In this paper we present a method for the dynamic visualization of cerebral blood flow. Spatio-temporal 4D magnetic resonance angiography (MRA) image datasets and 3D MRA datasets with high spatial resolution were acquired for the analysis of arteriovenous malformations (AVMs). One of the main tasks is the combination of the information of the 3D and 4D MRA image sequences. Initially, in the 3D MRA dataset the vessel system is segmented and a 3D surface model is generated. Then, temporal intensity curves are analyzed voxelwise in the 4D MRA image sequences. A curve fitting of the temporal intensity curves to a patient individual reference curve is used to extract the bolus arrival times in the 4D MRA sequences. After non-linear registration of both MRA datasets the extracted hemodynamic information is transferred to the surface model where the time points of inflow can be visualized color coded dynamically over time. The dynamic visualizations computed using the curve fitting method for the estimation of the bolus arrival times were rated superior compared to those computed using conventional approaches for bolus arrival time estimation. In summary the procedure suggested allows a dynamic visualization of the individual hemodynamic situation and better understanding during the visual evaluation of cerebral vascular diseases.
A parallel algorithm for 3D dislocation dynamics
NASA Astrophysics Data System (ADS)
Wang, Zhiqiang; Ghoniem, Nasr; Swaminarayan, Sriram; LeSar, Richard
2006-12-01
Dislocation dynamics (DD), a discrete dynamic simulation method in which dislocations are the fundamental entities, is a powerful tool for investigation of plasticity, deformation and fracture of materials at the micron length scale. However, severe computational difficulties arising from complex, long-range interactions between these curvilinear line defects limit the application of DD in the study of large-scale plastic deformation. We present here the development of a parallel algorithm for accelerated computer simulations of DD. By representing dislocations as a 3D set of dislocation particles, we show here that the problem of an interacting ensemble of dislocations can be converted to a problem of a particle ensemble, interacting with a long-range force field. A grid using binary space partitioning is constructed to keep track of node connectivity across domains. We demonstrate the computational efficiency of the parallel micro-plasticity code and discuss how O(N) methods map naturally onto the parallel data structure. Finally, we present results from applications of the parallel code to deformation in single crystal fcc metals.
Quaini, A.; Canic, S.; Glowinski, R.; Igo, S.; Hartley, C.J.; Zoghbi, W.; Little, S.
2011-01-01
This work presents a validation of a fluid-structure interaction computational model simulating the flow conditions in an in vitro mock heart chamber modeling mitral valve regurgitation during the ejection phase during which the trans-valvular pressure drop and valve displacement are not as large. The mock heart chamber was developed to study the use of 2D and 3D color Doppler techniques in imaging the clinically relevant complex intra-cardiac flow events associated with mitral regurgitation. Computational models are expected to play an important role in supporting, refining, and reinforcing the emerging 3D echocardiographic applications. We have developed a 3D computational fluid-structure interaction algorithm based on a semi-implicit, monolithic method, combined with an arbitrary Lagrangian-Eulerian approach to capture the fluid domain motion. The mock regurgitant mitral valve corresponding to an elastic plate with a geometric orifice, was modeled using 3D elasticity, while the blood flow was modeled using the 3D Navier-Stokes equations for an incompressible, viscous fluid. The two are coupled via the kinematic and dynamic conditions describing the two-way coupling. The pressure, the flow rate, and orifice plate displacement were measured and compared with numerical simulation results. In-line flow meter was used to measure the flow, pressure transducers were used to measure the pressure, and a Doppler method developed by one of the authors was used to measure the axial displacement of the orifice plate. The maximum recorded difference between experiment and numerical simulation for the flow rate was 4%, the pressure 3.6%, and for the orifice displacement 15%, showing excellent agreement between the two. PMID:22138194
A 3D-CFD code for accurate prediction of fluid flows and fluid forces in seals
NASA Technical Reports Server (NTRS)
Athavale, M. M.; Przekwas, A. J.; Hendricks, R. C.
1994-01-01
Current and future turbomachinery requires advanced seal configurations to control leakage, inhibit mixing of incompatible fluids and to control the rotodynamic response. In recognition of a deficiency in the existing predictive methodology for seals, a seven year effort was established in 1990 by NASA's Office of Aeronautics Exploration and Technology, under the Earth-to-Orbit Propulsion program, to develop validated Computational Fluid Dynamics (CFD) concepts, codes and analyses for seals. The effort will provide NASA and the U.S. Aerospace Industry with advanced CFD scientific codes and industrial codes for analyzing and designing turbomachinery seals. An advanced 3D CFD cylindrical seal code has been developed, incorporating state-of-the-art computational methodology for flow analysis in straight, tapered and stepped seals. Relevant computational features of the code include: stationary/rotating coordinates, cylindrical and general Body Fitted Coordinates (BFC) systems, high order differencing schemes, colocated variable arrangement, advanced turbulence models, incompressible/compressible flows, and moving grids. This paper presents the current status of code development, code demonstration for predicting rotordynamic coefficients, numerical parametric study of entrance loss coefficients for generic annular seals, and plans for code extensions to labyrinth, damping, and other seal configurations.
A new 3D dynamical biomechanical tongue model
NASA Astrophysics Data System (ADS)
Gerard, Jean-Michel; Perrier, Pascal; Payan, Yohan; Wilhelms-Tricarico, Reiner
2001-05-01
A new dynamical biomechanical tongue model is being developed to study speech motor control. In spite of its computational complexity, a 3D representation was chosen in order to account for various contacts between tongue and external structures such as teeth, palate, and vocal tract walls. A fair representation of tongue muscle anatomy is provided, by designing the finite element mesh from the visible human data set (female subject). Model geometry was then matched to a human speaker, so that simulations can be quantitatively compared to experimental MRI data. A set of 11 muscles is modeled, whose role in speech gestures is well established. Each muscle is defined by a set of elements whose elastic properties change with muscle activation. Muscles forces are applied to the tongue model via macrofibers defined within the mesh by muscle specific sets of nodes. These forces are currently specified as step functions. Boundary conditions are set using zero-displacement nodes simulating attachments of tongue on bony structures. The nonlinear mechanical properties of tongue soft tissues are modeled using a hyperelastic material. Three-dimensional tongue deformations generated by each muscle, using FEM software ANSYS for computation, will be presented. Implications for speech motor control will be proposed.
Computational Analysis of the Transonic Dynamics Tunnel Using FUN3D
NASA Technical Reports Server (NTRS)
Chwalowski, Pawel; Quon, Eliot; Brynildsen, Scott E.
2016-01-01
This paper presents results from an exploratory two-year effort of applying Computational Fluid Dynamics (CFD) to analyze the empty-tunnel flow in the NASA Langley Research Center Transonic Dynamics Tunnel (TDT). The TDT is a continuous-flow, closed circuit, 16- x 16-foot slotted-test-section wind tunnel, with capabilities to use air or heavy gas as a working fluid. In this study, experimental data acquired in the empty tunnel using the R-134a test medium was used to calibrate the computational data. The experimental calibration data includes wall pressures, boundary-layer profiles, and the tunnel centerline Mach number profiles. Subsonic and supersonic flow regimes were considered, focusing on Mach 0.5, 0.7 and Mach 1.1 in the TDT test section. This study discusses the computational domain, boundary conditions, and initial conditions selected and the resulting steady-state analyses using NASA's FUN3D CFD software.
RV functional imaging: 3-D echo-derived dynamic geometry and flow field simulations.
Pasipoularides, Ares D; Shu, Ming; Womack, Michael S; Shah, Ashish; Von Ramm, Olaf; Glower, Donald D
2003-01-01
We describe a novel functional imaging approach for quantitative analysis of right ventricular (RV) blood flow patterns in specific experimental animals (or humans) using real-time, three-dimensional (3-D) echocardiography (RT3D). The method is independent of the digital imaging modality used. It comprises three parts. First, a semiautomated segmentation aided by intraluminal contrast medium locates the RV endocardial surface. Second, a geometric scheme for dynamic RV chamber reconstruction applies a time interpolation procedure to the RT3D data to quantify wall geometry and motion at 400 Hz. A volumetric prism method validated the dynamic geometric reconstruction against simultaneous sonomicrometric canine measurements. Finally, the RV endocardial border motion information is used for mesh generation on a computational fluid dynamics solver to simulate development of the early RV diastolic inflow field. Boundary conditions (tessellated endocardial surface nodal velocities) for the solver are directly derived from the endocardial geometry and motion information. The new functional imaging approach may yield important kinematic information on the distribution of instantaneous velocities in the RV diastolic flow field of specific normal or diseased hearts. PMID:12388220
Computational Fluid Dynamics Library
2005-03-04
CFDLib05 is the Los Alamos Computational Fluid Dynamics LIBrary. This is a collection of hydrocodes using a common data structure and a common numerical method, for problems ranging from single-field, incompressible flow, to multi-species, multi-field, compressible flow. The data structure is multi-block, with a so-called structured grid in each block. The numerical method is a Finite-Volume scheme employing a state vector that is fully cell-centered. This means that the integral form of the conservation lawsmore » is solved on the physical domain that is represented by a mesh of control volumes. The typical control volume is an arbitrary quadrilateral in 2D and an arbitrary hexahedron in 3D. The Finite-Volume scheme is for time-unsteady flow and remains well coupled by means of time and space centered fluxes; if a steady state solution is required, the problem is integrated forward in time until the user is satisfied that the state is stationary.« less
A 3D GCL compatible cell-centered Lagrangian scheme for solving gas dynamics equations
NASA Astrophysics Data System (ADS)
Georges, Gabriel; Breil, Jérôme; Maire, Pierre-Henri
2016-01-01
Solving the gas dynamics equations under the Lagrangian formalism enables to simulate complex flows with strong shock waves. This formulation is well suited to the simulation of multi-material compressible fluid flows such as those encountered in the domain of High Energy Density Physics (HEDP). These types of flows are characterized by complex 3D structures such as hydrodynamic instabilities (Richtmyer-Meshkov, Rayleigh-Taylor, etc.). Recently, the 3D extension of different Lagrangian schemes has been proposed and appears to be challenging. More precisely, the definition of the cell geometry in the 3D space through the treatment of its non-planar faces and the limiting of a reconstructed field in 3D in the case of a second-order extension are of great interest. This paper proposes two new methods to solve these problems. A systematic and symmetric geometrical decomposition of polyhedral cells is presented. This method enables to define a discrete divergence operator leading to the respect of the Geometric Conservation Law (GCL). Moreover, a multi-dimensional minmod limiter is proposed. This new limiter constructs, from nodal gradients, a cell gradient which enables to ensure the monotonicity of the numerical solution even in presence of strong discontinuity. These new ingredients are employed into a cell-centered Lagrangian scheme. Robustness and accuracy are assessed against various representative test cases.
Conservation of Fluid Mass and Energy by RELAP5-3D during a SBLOCA
Cliff B. Davis
2009-08-01
Mass and energy balances were performed to check the accuracy of RELAP5-3D’s solution during a loss-of-coolant accident initiated by a small break in a typical pressurized water reactor. Mass and energy balances were performed for the combined liquid and gas phases and the gas phase by itself. The analysis showed that RELAP5-3D adequately conserved mass and energy for the combined fluid and the gas phase.
Navier-Stokes Neutral and Plasma Fluid Modelling in 3D
Riemann, J; Borchardt, M; Schneider, R; Mutzke, A; Rognlien, T; Umansky, M
2004-05-17
The 3D finite volume transport code BoRiS is applied to a system of coupled plasma and neutral fluid equations in a slab. Demonstrating easy implementation of new equations, a new parallel BoRiS version is tested on three different models for the neutral fluid - diffusive, parallel Navier-Stokes and full Navier-Stokes - and the results are compared to each other. Typical effects like density enhancement by ionization of recycled neutrals in front of a target plate can be seen and differences are linked to the neutral models in use.
Dynamics of tokamak plasma surface current in 3D ideal MHD model
NASA Astrophysics Data System (ADS)
Galkin, Sergei A.; Svidzinski, V. A.; Zakharov, L. E.
2013-10-01
Interest in the surface current which can arise on perturbed sharp plasma vacuum interface in tokamaks was recently generated by a few papers (see and references therein). In dangerous disruption events with plasma-touching-wall scenarios, the surface current can be shared with the wall leading to the strong, damaging forces acting on the wall A relatively simple analytic definition of δ-function surface current proportional to a jump of tangential component of magnetic field nevertheless leads to a complex computational problem on the moving plasma-vacuum interface, requiring the incorporation of non-linear 3D plasma dynamics even in one-fluid ideal MHD. The Disruption Simulation Code (DSC), which had recently been developed in a fully 3D toroidal geometry with adaptation to the moving plasma boundary, is an appropriate tool for accurate self-consistent δfunction surface current calculation. Progress on the DSC-3D development will be presented. Self-consistent surface current calculation under non-linear dynamics of low m kink mode and VDE will be discussed. Work is supported by the US DOE SBIR grant #DE-SC0004487.
NASA Astrophysics Data System (ADS)
Tsuji, Takeshi; Jiang, Fei; Christensen, Kenneth T.
2016-09-01
To characterize the influence of reservoir conditions upon multiphase flow, we calculated fluid displacements (drainage processes) in 3D pore spaces of Berea sandstone using two-phase lattice Boltzmann (LB) simulations. The results of simulations under various conditions were used to classify the resulting two-phase flow behavior into three typical fluid displacement patterns on the diagram of capillary number (Ca) and viscosity ratio of the two fluids (M). In addition, the saturation of the nonwetting phase was calculated and mapped on the Ca-M diagram. We then characterized dynamic pore-filling events (i.e., Haines jumps) from the pressure variation of the nonwetting phase, and linked this behavior to the occurrence of capillary fingering. The results revealed the onset of capillary fingering in 3D natural rock at a higher Ca than in 2D homogeneous granular models, with the crossover region between typical displacement patterns broader than in the homogeneous granular model. Furthermore, saturation of the nonwetting phase mapped on the Ca-M diagram significantly depends on the rock models. These important differences between two-phase flow in 3D natural rock and in 2D homogeneous models could be due to the heterogeneity of pore geometry in the natural rock and differences in pore connectivity. By quantifying two-phase fluid behavior in the target reservoir rock under various conditions (e.g., saturation mapping on the Ca-M diagram), our approach could provide useful information for investigating suitable reservoir conditions for geo-fluid management (e.g., high CO2 saturation in CO2 storage).
North Cascadia heat flux and fluid flow from gas hydrates: Modeling 3-D topographic effects
NASA Astrophysics Data System (ADS)
Li, Hong-lin; He, Tao; Spence, George D.
2014-01-01
The bottom-simulating reflector (BSR) of gas hydrate is well imaged from two perpendicular seismic grids in the region of a large carbonate mound, informally called Cucumber Ridge off Vancouver Island. We use a new method to calculate 3-D heat flow map from the BSR depths, in which we incorporate 3-D topographic corrections after calibrated by the drilling results from nearby (Integrated) Ocean Drilling Program Site 889 and Site U1327. We then estimate the associated fluid flow by relating it to the topographically corrected heat flux anomalies. In the midslope region, a heat flux anomaly of 1 mW/m2 can be associated with an approximate focused fluid flow rate of 0.09 mm/yr. Around Cucumber Ridge, high rates of focused fluid flow were observed at steep slopes with values more than double the average regional diffusive fluid discharge rate of 0.56 mm/yr. As well, in some areas of relatively flat seafloor, the focused fluid flow rates still exceeded 0.5 mm/yr. On the seismic lines the regions of focused fluid flow were commonly associated with seismic blanking zones above the BSR and sometimes with strong reflectors below the BSR, indicating that the faults/fractures provide high-permeability pathways for fluids to carry methane from BSR depths to the seafloor. These high fluid flow regions cover mostly the western portion of our area with gas hydrate concentration estimations of ~6% based on empirical correlations from Hydrate Ridge in south off Oregon, significantly higher than previously recognized values of ~2.5% in the eastern portion determined from Site U1327.
3D High-Resolution Seismic Imaging of Fluid Flow Anomalies on the Norwegian Continental Shelf
NASA Astrophysics Data System (ADS)
Planke, S.; Eriksen, F. N.; Eriksen, O. K.; Myklebust, R.; Stokke, H. H.
2015-12-01
Fluid flow anomalies are common on the Norwegian Continental Shelf. Such features are imaged by multiple P-Cable high resolution seismic 2D lines and 3D cubes in the Norwegian Barents Sea. P-Cable is a high resolution 3D seismic system consisting of multiple streamers attached to a cross cable that is towed perpendicular to the vessels steaming direction. The short offset, high frequency source and closely spaced streamers facilitates for excellent vertical and horizontal resolution that provides key information for understanding the sub-surface. Recent data have been broadband processed, and the method has proven to enhance the imaging of the sub-surface significantly. Barents Sea P-Cable surveys have targeted shallow fluid anomalies in the uppermost ca. 500 meters of the sub-surface. New data have been acquired in 2012, 2014 and 2015. The most recent data focus on the southeast part of the Norwegian Barents Sea where P-Cable data give a new insight into the subsurface not provided by conventional seismic data in the region. Geologically, the Barents Sea region is characterized by Paleozoic and Mesozoic siliciclastic successions overlaid in most areas by a thin cover of Cenozoic glacial sediments. Hydrocarbon-rich Jurassic and Triassic sequences are locally situated in the shallow sub-surface as a result of extensive late Cenozoic uplift and erosion. The unloading has been reported to reactivate and create new faults in addition to initiate further migration of fluids in the sub-surface (Chand et al., 2012). The presence of shallow hydrocarbon systems creates an optimal setting for imaging fluid flow anomalies with high resolution 3D seismic data. The Barents Sea P-Cable data image a range of fluid related features such as cross-cutting reflections and bright spots, chimney structures, acoustic masking, pockmarks and mud volcanoes.
Calcium signaling in response to fluid flow by chondrocytes in 3D alginate culture.
Degala, Satish; Williams, Rebecca; Zipfel, Warren; Bonassar, Lawrence J
2012-05-01
Quantifying the effects of mechanical loading on the metabolic response of chondrocytes is difficult due to complicated structure of cartilage ECM and the coupled nature of the mechanical stimuli presented to the cells. In this study we describe the effects of fluid flow, particularly hydrostatic pressure and wall shear stress, on the Ca(2+) signaling response of bovine articular chondrocytes in 3D culture. Using well-established alginate hydrogel system to maintain spherical chondrocyte morphology, we altered solid volume fraction to change scaffold mechanics. Fluid velocities in the bulk of the scaffolds were directly measured via an optical technique and scaffold permeability and aggregate modulus was characterized to quantify the mechanical stimuli presented to cells. Ca(2+) signaling response to direct perfusion of chondrocyte-seeded scaffolds increased monotonically with flow rate and was found more directly dependent on fluid velocity rather than shear stress or hydrostatic pressure. Chondrocytes in alginate scaffolds responded to fluid flow at velocities and shear stresses 2-3 orders of magnitude lower than seen in previous monolayer studies. Our data suggest that flow-induced Ca(2+) signaling response of chondrocytes in alginate culture may be due to mechanical signaling pathways, which is influenced by the 3D nature of cell shape.
NASA Technical Reports Server (NTRS)
1989-01-01
An overview of computational fluid dynamics (CFD) activities at the Langley Research Center is given. The role of supercomputers in CFD research, algorithm development, multigrid approaches to computational fluid flows, aerodynamics computer programs, computational grid generation, turbulence research, and studies of rarefied gas flows are among the topics that are briefly surveyed.
A multiscale 3D finite element analysis of fluid/solute transport in mechanically loaded bone
Fan, Lixia; Pei, Shaopeng; Lucas Lu, X; Wang, Liyun
2016-01-01
The transport of fluid, nutrients, and signaling molecules in the bone lacunar–canalicular system (LCS) is critical for osteocyte survival and function. We have applied the fluorescence recovery after photobleaching (FRAP) approach to quantify load-induced fluid and solute transport in the LCS in situ, but the measurements were limited to cortical regions 30–50 μm underneath the periosteum due to the constrains of laser penetration. With this work, we aimed to expand our understanding of load-induced fluid and solute transport in both trabecular and cortical bone using a multiscaled image-based finite element analysis (FEA) approach. An intact murine tibia was first re-constructed from microCT images into a three-dimensional (3D) linear elastic FEA model, and the matrix deformations at various locations were calculated under axial loading. A segment of the above 3D model was then imported to the biphasic poroelasticity analysis platform (FEBio) to predict load-induced fluid pressure fields, and interstitial solute/fluid flows through LCS in both cortical and trabecular regions. Further, secondary flow effects such as the shear stress and/or drag force acting on osteocytes, the presumed mechano-sensors in bone, were derived using the previously developed ultrastructural model of Brinkman flow in the canaliculi. The material properties assumed in the FEA models were validated against previously obtained strain and FRAP transport data measured on the cortical cortex. Our results demonstrated the feasibility of this computational approach in estimating the fluid flux in the LCS and the cellular stimulation forces (shear and drag forces) for osteocytes in any cortical and trabecular bone locations, allowing further studies of how the activation of osteocytes correlates with in vivo functional bone formation. The study provides a promising platform to reveal potential cellular mechanisms underlying the anabolic power of exercises and physical activities in
ERIC Educational Resources Information Center
Bird, R. Byron
1980-01-01
Problems in polymer fluid dynamics are described, including development of constitutive equations, rheometry, kinetic theory, flow visualization, heat transfer studies, flows with phase change, two-phase flow, polymer unit operations, and drag reduction. (JN)
DREAM3D simulations of inner-belt dynamics
Cunningham, Gregory Scott
2015-05-26
A 1973 paper by Lyons and Thorne explains the two-belt structure for electrons in the inner magnetosphere as a balance between inward radial diffusion and loss to the atmosphere, where the loss to the atmosphere is enabled by pitch-angle scattering from Coulomb and wave-particle interactions. In the 1973 paper, equilibrium solutions to a decoupled set of 1D radial diffusion equations, one for each value of the first invariant of motion, μ, were computed to produce the equilibrium two-belt structure. Each 1D radial diffusion equation incorporated an L-and μ-dependent `lifetime' due to the Coulomb and wave-particle interactions. This decoupling of the problem is appropriate under the assumption that radial diffusion is slow in comparison to pitch-angle scattering. However, for some values of μ and L the lifetime associated with pitch-angle scattering is comparable to the timescale associated with radial diffusion, suggesting that the true equilibrium solutions might reflect `coupled modes' involving pitch-angle scattering and radial diffusion and thus requiring a 3D diffusion model. In the work we show here, we have computed the equilibrium solutions using our 3D diffusion model, DREAM3D, that allows for such coupling. We find that the 3D equilibrium solutions are quite similar to the solutions shown in the 1973 paper when we use the same physical models for radial diffusion and pitch-angle scattering from hiss. However, we show that the equilibrium solutions are quite sensitive to various aspects of the physics model employed in the 1973 paper that can be improved, suggesting that additional work needs to be done to understand the two-belt structure.
Computational fluid dynamic control
NASA Technical Reports Server (NTRS)
Hartley, Tom T.; Deabreu-Garcia, Alex
1989-01-01
A general technique is presented for modeling fluid, or gas, dynamic systems specifically for the development of control systems. The numerical methods which are generally used in computational fluid dynamics are borrowed to create either continuous-time or discrete-time models of the particular fluid system. The resulting equations can be either left in a nonlinear form, or easily linearized about an operating point. As there are typically very many states in these systems, the usual linear model reduction methods can be used on them to allow a low-order controller to be designed. A simple example is given which typifies many internal flow control problems. The resulting control is termed computational fluid dynamic control.
NASA Astrophysics Data System (ADS)
Guo, Liancheng; Morita, Koji; Tagami, Hirotaka; Tobita, Yoshiharu
2014-06-01
The postulated core disruptive accidents (CDAs) are regarded as particular difficulties in the safety analysis of liquid-metal fast reactors (LMFRs). In CDAs, the motions and interactions of solid particles, such as refrozen fuels, disrupted pellets, etc., not only dominate fundamental behaviors of multiphase flows, but also drastically influence the process of CDAs. The fast reactor safety analysis code, SIMMER-IV, which is a 3D, multi-velocity-field, multiphase, multicomponent, Eulerian, fluid dynamics code coupled with a fuel-pin model and a space- and energy-dependent neutron kinetics model, was successfully applied to a series of CDA assessments. However, strong interactions among solid particles as well as particle characteristics in multiphase flows with rich solid particles were not taken into consideration for fluid-dynamics models of SIMMER-IV. In this article, a hybrid method for multiphase flow analysis is developed by coupling the discrete element method (DEM) with the multi-fluid model of SIMMER-IV. In the coupling algorithm, motions of liquid and gas phases are solved by a time-factorization (time-splitting) method. For the solid phases, contacts among particles and interactions with fluid phases are considered through DEM. Numerical simulations of dam-break behavior with rich solid particles show reasonable agreements with corresponding experimental results. It is expected that SIMMER-IV coupled with DEM could provide a promising and useful computational tool for complicated multiphase-flow phenomena with high concentration of solid particles.
NASA Astrophysics Data System (ADS)
Kluesner, J.; Brothers, D. S.; Johnson, S. Y.; Watt, J. T.
2015-12-01
High-resolution 3D seismic P-Cable data and advanced seismic attribute analyses were used to detect and interpret complex strike-slip fault geometries, deformation patterns, and fluid-pathways across a portion of the Hosgri Fault Zone (HFZ) offshore central California. Combination of the fault attribute results with structural analysis provides 3D insight into the geometry and internal structure of restraining and releasing bends, step-over zones, fault convergence zones, and apparent paired fault bends. The 3D seismic volume covers a 13.7 km2 region along the HFZ offshore of Point Sal and was collected in 2012 as part of the PG&E Central California Seismic Imaging Project (PG&E, 2014). Application of the fault attribute workflow isolated and delineated fault strands within the 3D volume. These results revealed that the northern and southern edges of the survey region are characterized by single fault strands that exhibit an approximate 6° change in strike across the 3D volume. Between these single faults strands is a complex network of fault splays, bends, stepovers, and convergence zones. Structural analysis reveals that the southern portion of the HFZ in the region is characterized by transtensional deformation, whereas transpressional-related folding dominates the central and northern portions of the HFZ. In the central region, convergence of the Lions Head Fault from the southeast results in an apparent impinging block, leading to development of a "paired fault bend" to the west. Combination of the fault and "chimney" attribute results indicates a strong connection between faults and fluid-migration pathways. Fluid-pathways are concentrated along discrete faults in the transtensional zones, but appear to be more broadly distributed amongst fault bounded anticlines and structurally controlled traps in the transpressional zones.
TRACE3D. Interactive Beam-Dynamics Program
Singleton, L.; Yao, C.Y.
1993-12-01
TRACE3D is an interactive program that calculates the envelopes of a bunched beam, including linear space-charge forces, through a user-defined system. The transport system may consist of the following elements: drift, thin lens, quadrupole, permanent magnet quadrupole, solenoid, doublet, triplet, bending magnet, edge angle (for bend), RF gap, radio-frequency-quadrupole cell, RF cavity, coupled-cavity tank, user-desired element, coordinate rotation, and identical element. The beam is represented by a 6X6 matrix defining a hyper-ellipsoid in six-dimensional phase space. The projection of this hyperellipsoid on any two-dimensional plane is an ellipse that defines the boundary of the beam in that plane.
TRACE3D. Interactive Beam-Dynamics Program
Crandall, K.R.; Rusthoi, D.P.
1991-06-01
TRACE3D is an interactive program that calculates the envelopes of a bunched beam, including linear space-charge forces, through a user-defined system. The transport system may consist of the following elements: drift, thin lens, quadrupole, permanent magnet quadrupole, solenoid, doublet, triplet, bending magnet, edge angle (for bend), RF gap, radio-frequency-quadrupole cell, RF cavity, coupled-cavity tank, user-desired element, coordinate rotation, and identical element. The beam is represented by a 6X6 matrix defining a hyper-ellipsoid in six-dimensional phase space. The projection of this hyperellipsoid on any two-dimensional plane is an ellipse that defines the boundary of the beam in that plane.
3D topographic correction of the BSR heat flow and detection of focused fluid flow
NASA Astrophysics Data System (ADS)
He, Tao; Li, Hong-Lin; Zou, Chang-Chun
2014-06-01
The bottom-simulating reflector (BSR) is a seismic indicator of the bottom of a gas hydrate stability zone. Its depth can be used to calculate the seafloor surface heat flow. The calculated BSR heat flow variations include disturbances from two important factors: (1) seafloor topography, which focuses the heat flow over regions of concave topography and defocuses it over regions of convex topography, and (2) the focused warm fluid flow within the accretionary prism coming from depths deeper than BSR. The focused fluid flow can be detected if the contribution of the topography to the BSR heat flow is removed. However, the analytical equation cannot solve the topographic effect at complex seafloor regions. We prove that 3D finite element method can model the topographic effect on the regional background heat flow with high accuracy, which can then be used to correct the topographic effect and obtain the BSR heat flow under the condition of perfectly flat topography. By comparing the corrected BSR heat flow with the regional background heat flow, focused fluid flow regions can be detected that are originally too small and cannot be detected using present-day equipment. This method was successfully applied to the midslope region of northern Cascadia subducting margin. The results suggest that the Cucumber Ridge and its neighboring area are positive heat flow anomalies, about 10%-20% higher than the background heat flow after 3D topographic correction. Moreover, the seismic imaging associated the positive heat flow anomaly areas with seabed fracture-cavity systems. This suggests flow of warm gas-carrying fluids along these high-permeability pathways, which could result in higher gas hydrate concentrations.
How effective can optical-CT 3D dosimetry be without refractive fluid matching?
Rankine, L; Oldham
2013-01-01
Achieving accurate optical CT 3D dosimetry without the use of viscous refractive index (RI) matching fluids would greatly increase convenience. Software has been developed to simulate optical CT 3D dosimetry for a range of scanning configurations including parallel-beam, point and converging light sources. For each configuration the efficacy of 3 refractive media were investigated: air, water, and a fluid closely matched to Presage (RI = 1.00, 1.33 and 1.49 respectively). The results revealed that the useable radius of the dosimeter (i.e. where data was within 2% of truth) reduced to 68% for water-matching, and 31% for dry-scanning in air. Point source incident ray geometry produced slightly more favourable results, although variation between the three geometries was relatively small. The required detector size however, increased by a factor six for dry-scanning, introducing cost penalties. For applications where dose information is not required in the periphery, some dry and low-viscous matching configurations may be feasible. PMID:24454520
The vibrational dynamics of 3D HOCl above dissociation
Lin, Yi-Der; Reichl, L. E.; Jung, Christof
2015-03-28
We explore the classical vibrational dynamics of the HOCl molecule for energies above the dissociation energy of the molecule. Above dissociation, we find that the classical dynamics is dominated by an invariant manifold which appears to stabilize two periodic orbits at energies significantly above the dissociation energy. These stable periodic orbits can hold a large number of quantum states and likely can support a significant quasibound state of the molecule, well above the dissociation energy. The classical dynamics and the lifetime of quantum states on the invariant manifold are determined.
Code verification for unsteady 3-D fluid-solid interaction problems
NASA Astrophysics Data System (ADS)
Yu, Kintak Raymond; Étienne, Stéphane; Hay, Alexander; Pelletier, Dominique
2015-12-01
This paper describes a procedure to synthesize Manufactured Solutions for Code Verification of an important class of Fluid-Structure Interaction (FSI) problems whose behaviors can be modeled as rigid body vibrations in incompressible fluids. We refer this class of FSI problems as Fluid-Solid Interaction problems, which can be found in many practical engineering applications. The methodology can be utilized to develop Manufactured Solutions for both 2-D and 3-D cases. We demonstrate the procedure with our numerical code. We present details of the formulation and methodology. We also provide the reasonings behind our proposed approach. Results from grid and time step refinement studies confirm the verification of our solver and demonstrate the versatility of the simple synthesis procedure. In addition, the results also demonstrate that the modified decoupled approach to verify flow problems with high-order time-stepping schemes can be employed equally well to verify code for multi-physics problems (here, those of the Fluid-Solid Interaction) when the numerical discretization is based on the Method of Lines.
A fully 3-D molecular dynamics study of the initiation of the Kelvin-Helmholtz instability
NASA Astrophysics Data System (ADS)
Rudd, Robert E.; Caspersen, K. J.; Richards, D. F.; Glosli, J. N.; Gunnels, J. A.; Streitz, F. H.
2008-03-01
The modeling of hydrodynamic phenomena has almost exclusively been the purview of continuum mechanics, specifically, through the use of the Navier-Stokes equation and closely related variants. Nevertheless, at the smallest length scales, where atomistic effects become important, it is not clear that this continuum approach provides a complete description of fluid behavior. To understand the effects of atomistics, we have performed a 62.5-billion-atom, fully 3-D molecular dynamics simulation of a cubic micron of molten copper and aluminum. The shear flow at 2 km/s exhibits complex phenomena associated with a Kelvin-Helmholtz (KH) instability. In this presentation we will discuss the initiation and early evolution of the KH instability, focusing specifically on the effects of full atomistic resolution.
Relativistic fluid dynamics. Proceedings.
NASA Astrophysics Data System (ADS)
Anile, A. M.; Choquet-Bruhat, Y.
Contents: 1. Covariant theory of conductivity in ideal fluid or solid media (B. Carter). 2. Hamiltonian techniques for relativistic fluid dynamics and stability theory (D. D. Holm). 3. Covariant fluid mechanics and thermodynamics: an introduction (W. Israel). 4. Relativistic plasmas (H. Weitzner). 5. An improved relativistic warm plasma model (A. M. Anile, S. Pennisi). 6. Relativistic extended thermodynamics II (I. Müller). 7. Relativistic extended thermodynamics: general assumptions and mathematical procedure (T. Ruggeri). 8. Relativistic hydrodynamics and heavy ion reactions (D. Strottman). 9. Some problems in relativistic hydrodynamics (C. G. van Weert).
Guidelines in the experimental validation of a 3D heat and fluid flow model of keyhole laser welding
NASA Astrophysics Data System (ADS)
Courtois, Mickael; Carin, Muriel; Le Masson, Philippe; Gaied, Sadok; Balabane, Mikhaël
2016-04-01
During the past few years, numerous sophisticated models have been proposed to predict in a self-consistent way the dynamics of the keyhole, together with the melt pool and vapor jet. However, these models are only partially compared to experimental data, so the reliability of these models is questionable. The present paper aims to propose a more complete experimental set-up in order to validate the most relevant results calculated by these models. A complete heat transfer and fluid flow three-dimensional (3D) model is first proposed in order to describe laser welding in keyhole regimes. The interface is tracked with a level set method and fluid flows are calculated in liquid and gas. The mechanisms of recoil pressure and keyhole creation are highlighted in a fusion line configuration chosen as a reference. Moreover, a complete validation of the model is proposed with guidelines on the variables to observe. Numerous comparisons with dedicated experiments (thermocouples, pyrometry, high-speed camera) are proposed to estimate the validity of the model. In addition to traditional geometric measurements, the main variables calculated, temperatures, and velocities in the melt pool are at the center of this work. The goal is to propose a reference validation for complex 3D models proposed over the last few years.
Borazjani, Iman; Ge, Liang; Sotiropoulos, Fotis
2010-01-01
The sharp-interface CURVIB approach of Ge and Sotiropoulos [L. Ge, F. Sotiropoulos, A Numerical Method for Solving the 3D Unsteady Incompressible Navier-Stokes Equations in Curvilinear Domains with Complex Immersed Boundaries, Journal of Computational Physics 225 (2007) 1782–1809] is extended to simulate fluid structure interaction (FSI) problems involving complex 3D rigid bodies undergoing large structural displacements. The FSI solver adopts the partitioned FSI solution approach and both loose and strong coupling strategies are implemented. The interfaces between immersed bodies and the fluid are discretized with a Lagrangian grid and tracked with an explicit front-tracking approach. An efficient ray-tracing algorithm is developed to quickly identify the relationship between the background grid and the moving bodies. Numerical experiments are carried out for two FSI problems: vortex induced vibration of elastically mounted cylinders and flow through a bileaflet mechanical heart valve at physiologic conditions. For both cases the computed results are in excellent agreement with benchmark simulations and experimental measurements. The numerical experiments suggest that both the properties of the structure (mass, geometry) and the local flow conditions can play an important role in determining the stability of the FSI algorithm. Under certain conditions unconditionally unstable iteration schemes result even when strong coupling FSI is employed. For such cases, however, combining the strong-coupling iteration with under-relaxation in conjunction with the Aitken’s acceleration technique is shown to effectively resolve the stability problems. A theoretical analysis is presented to explain the findings of the numerical experiments. It is shown that the ratio of the added mass to the mass of the structure as well as the sign of the local time rate of change of the force or moment imparted on the structure by the fluid determine the stability and convergence of the
3D RECONNECTION AND FLOW DYNAMICS IN THE SSX EXPERIMENT
Brown, M. R.; Cothran, C. D.; Cohen, D. H.; Horwitz, J.; Chaplin, V.
2009-07-26
Several new experimental results are reported from plasma merging studies at the Swarthmore Spheromak Experiment (SSX) with relevance to collisionless three-dimensional magnetic reconnection in laboratory and space plasmas. First, recent high-resolution velocity measurements of impurity ions using ion Doppler spectroscopy (IDS) show bi-directional outflow jets at 40 km/s (nearly the Alfven speed). The SSX IDS instrument measures with 1 mus or better time resolution the width and Doppler shift of the C{sub III} impurity (H plasma) 229.7 nm line to determine the temperature and line-averaged flow velocity during spheromak merging events. High flow speeds are corroborated using an in situ Mach probe. Second, ion heating to nearly 10{sup 6} K is observed after reconnection events in a low-density kinetic regime. Transient electron heating is inferred from bursts on a 4-channel soft x-ray array as well as vacuum ultraviolet spectroscopy. Third, the out-of-plane magnetic field and the in-plane Lorentz force in a reconnection volume both show a quadrupolar structure at the ion inertial scale (c/omega{sub pi}). Time resolved vector magnetic field measurements on a 3D lattice B(r, t)) enables this measurement. Earlier work at SSX has shown that formation of three-dimensional structure at the ion inertial scale is temporally and spatially correlated with the observation of superthermal, super-Alfvenic ions accelerated along the X-line normal to the local 2D plane of reconnection. Each of these measurements will be related to and compared with similar observations in a solar or space context. Keywords: spheromak, flow, heating.
3D visualization of deformation structures and potential fluid pathways at the Grimsel Test Site
NASA Astrophysics Data System (ADS)
Schneeberger, Raphael; Kober, Florian; Berger, Alfons; Spillmann, Thomas; Herwegh, Marco
2015-04-01
Knowledge on the ability of fluids to infiltrate subsurface rocks is of major importance for underground constructions, geothermal or radioactive waste disposal projects. In this study, we focus on the characterization of water infiltration pathways, their 3D geometries and origins. Based on surface and subsurface mapping in combination with drill core data, we developed by the use of MoveTM (Midland Valley Exploration Ltd.) a 3D structural model of the Grimsel Test Site (GTS). GTS is an underground laboratory operated by NAGRA, the Swiss organisation responsible for the management of nuclear waste. It is located within a suite of post-Variscan magmatic bodies comprising former granitic and granodioritic melts, which are dissected by mafic and aplitic dikes. During Alpine orogeny, the suite was tectonically overprinted within two stages of ductile deformation (Wehrens et al., in prep.) followed by brittle overprint of some of the shear zones during the retrograde exhumation history. It is this brittle deformation, which controls today's water infiltration network. However, the associated fractures, cataclasites and fault gouges are controlled themselves by aforementioned pre-existing mechanical discontinuities, whose origin ranges back as far as to the magmatic stage. For example, two sets of vertically oriented mafic dikes (E-W and NW-SE striking) and compositional heterogeneities induced by magmatic segregation processes in the plutonic host rocks served as nucleation sites for Alpine strain localization. Subsequently, NE-SW, E-W and NW-SE striking ductile shear zones were formed, in combination with high temperature fracturing while dissecting the host rocks in a complex 3D pattern (Wehrens et al, in prep.). Whether the ductile shear zones have been subjected to brittle reactivation and can serve as infiltration pathways or not, depends strongly on their orientations with respect to the principal stress field. Especially where deformation structures intersect
ORPHEE 3D: Static and dynamic tridimensional BHA computer models
Birades, M.
1986-01-01
Elf Aquitaine, within an ARTEP research project granted by EEC, has developed two three-dimensional mathematical models to predict the directional behavior of bottom hole assemblies (BHAs). Both models simulate BHAs by finite element methods. The first model describes dynamically their transient behavior step by step during short time intervals which are continuously adjusted to attain the required precision. Displacements and lateral forces, computed for each step, integrate friction against the borehole wall through a sophisticated shock algorithm. The second model computes a static equilibrium of the BHA while assuming simplified friction forces at the contact points between the wellbore and the BHA. The lateral forces and displacements are found to be an average of the highly varying ones computed by the dynamic model and the static computer run is much faster.
Dynamics of 3D view invariance in monkey inferotemporal cortex.
Ratan Murty, N Apurva; Arun, Sripati P
2015-04-01
Rotations in depth are challenging for object vision because features can appear, disappear, be stretched or compressed. Yet we easily recognize objects across views. Are the underlying representations view invariant or dependent? This question has been intensely debated in human vision, but the neuronal representations remain poorly understood. Here, we show that for naturalistic objects, neurons in the monkey inferotemporal (IT) cortex undergo a dynamic transition in time, whereby they are initially sensitive to viewpoint and later encode view-invariant object identity. This transition depended on two aspects of object structure: it was strongest when objects foreshortened strongly across views and were similar to each other. View invariance in IT neurons was present even when objects were reduced to silhouettes, suggesting that it can arise through similarity between external contours of objects across views. Our results elucidate the viewpoint debate by showing that view invariance arises dynamically in IT neurons out of a representation that is initially view dependent.
Introducing a New 3D Dynamical Model for Barred Galaxies
NASA Astrophysics Data System (ADS)
Jung, Christof; Zotos, Euaggelos E.
2015-11-01
The regular or chaotic dynamics of an analytical realistic three dimensional model composed of a spherically symmetric central nucleus, a bar and a flat disk is investigated. For describing the properties of the bar, we introduce a new simple dynamical model and we explore the influence on the character of orbits of all the involved parameters of it, such as the mass and the scale length of the bar, the major semi-axis and the angular velocity of the bar, as well as the energy. Regions of phase space with ordered and chaotic motion are identified in dependence on these parameters and for breaking the rotational symmetry. First, we study in detail the dynamics in the invariant plane z = pz = 0 using the Poincaré map as a basic tool and then study the full three-dimensional case using the Smaller Alignment index method as principal tool for distinguishing between order and chaos. We also present strong evidence obtained through the numerical simulations that our new bar model can realistically describe the formation and the evolution of the observed twin spiral structure in barred galaxies.
3-D consistency dynamic constitutive model of concrete
NASA Astrophysics Data System (ADS)
Xiao, Shiyun; Li, Hongnan; Lin, Gao
2010-06-01
Based on the consistency-viscoplastic constitutive model, the static William-Warnke model with threeparameters is modified and a consistency-viscoplastic William-Warnke model with three-parameters is developed that considers the effect of strain rates. Then, the tangent modulus of the consistency viscoplastic model is introduced and an implicit backward Elure iterative algorithm is developed. Comparisons between the numerical simulations and experimental data show that the consistency model properly provides the uniaxial and biaxial dynamic behaviors of concrete. To study the effect of strain rates on the dynamic response of concrete structures, the proposed model is used in the analysis of the dynamic response of a simply-supported beam and the results show that the strain rate has a significant effect on the displacement and stress magnitudes and distributions. Finally, the seismic responses of a 278 m high arch dam are obtained and compared by using the linear elastic model, as well as rate-independent and rate-dependent William-Warnke three-parameter models. The results indicate that the strain rate affects the first principal stresses, and the maximal equivalent viscoplastic strain rate of the arch dam. Numerical calculations and analyses reveal that considering the strain rate is important in the safety assessments of arch dams located in seismically active areas.
Two-Fluid Extensions to the M3D CDX-U Validation Study
NASA Astrophysics Data System (ADS)
Breslau, J.; Strauss, H.; Sugiyama, L.
2005-10-01
As part of a cross-code verification and validation effort, both the M3D code [1] and the NIMROD code [2] have qualitatively reproduced the nonlinear behavior of a complete sawtooth cycle in the CDX-U tokamak, chosen for the study because its low temperature and small size puts it in a parameter regime easily accessible to both codes. Initial M3D studies on this problem used a resistive MHD model with a large, empirical perpendicular heat transport value and with modest toroidal resolution (24 toroidal planes). The success of this study prompted the pursuit of more quantitatively accurate predictions by the application of more sophisticated physical models and higher numerical resolution. The results of two consequent follow-up studies are presented here. In the first, the toroidal resolution of the original run is doubled to 48 planes. The behavior of the sawtooth in this case is essentially the same as in the lower- resolution study. The sawtooth study has also been repeated using a two-fluid plasma model, with the effects of the &*circ;i term emphasized. The resulting mode rotation, as well as the effects on the reconnection rate (sawtooth crash time), sawtooth period, and overall stability are presented. [1] W. Park, et al., Phys. Plasmas 6, 1796 (1999). [2] C. Sovinec, et al., J. Comp. Phys. 195, 355 (2004).
Fluid force and static symmetry breaking modes of 3D bluff bodies.
NASA Astrophysics Data System (ADS)
Cadot, Olivier; Evrard, Antoine; DFA Team
2015-11-01
A cavity at the base of the squareback Ahmed model at Re =6.106 is able to reduce the base suction by 18% and the drag coefficient by 9%, while the flow at the separation remains unaffected. Instantaneous pressure measurements at the body base, fluid force measurements and wake velocity measurements are investigated varying the cavity depth from 0 to 35% of the base height. Due to the reflectional symmetry of the rectangular base, there are two Reflectional Symmetry Breaking (RSB) mirror modes present in the natural wake that switch from one to the other randomly in accordance with the recent findings of Grandemange et al. (2013). It is shown that these modes exhibit an energetic 3D static vortex system close to the base of the body. A sufficiently deep cavity is able to stabilize the wake toward a symmetry preserved wake, thus suppressing the RSB modes and leading to a weaker elliptical toric recirculation. The stabilization can be modeled with a Langevin equation. The plausible mechanism for drag reduction with the base cavity is based on the interaction of the static 3D vortex system of the RSB modes with the base and their suppression by stabilization. There are some strong evidences that this mechanism may be generalized to axisymmetric bodies with base cavity.
Dynamic Concrete Beam Deformation Measuremnet with 3d Range Cameras
NASA Astrophysics Data System (ADS)
Qi, X.; Lichti, D.
2012-07-01
Concrete beams are used to construct bridges and other structures. Due to the traffic overloading or the decaying state of structures, deformation of bridges or other structures occurs frequently. Therefore, the requirement to measure concrete beam deformation, as integral components of structures, is well recognized. Many imaging techniques such as digital cameras, laser scanners and range cameras have been proven to be accurate and cost-effective methods for large-area measurement of deformation under static loading conditions. However, for obtaining useful information about the behaviour of the beams or monitoring real-time bridge deformation, the ability to measurement deformation under dynamic loading conditions is also necessary. This paper presents a relatively low-cost and high accuracy imaging technique to measure the deformation of concrete beams in response to dynamic loading with range cameras. However, due to the range camera measurement principle, target movement could lead to motion artefacts that degrade range measurement accuracy. The results of simulated and real-data investigation into the motion artefacts show that the lower sampling frequency leads to the more significant motion artefact. The results from real data experiments have indicated that periodic deformation can be recovered with sub-millimetre accuracy when the 3 Hz and 4 mm amplitude target motion is sampled at a rate of least 20 Hz and with 31 MHz range camera modulation frequency. When the modulation frequency is 29 MHz, the best sampling frequency is 20 Hz to keep the error under sub-millimetre.
NASA Astrophysics Data System (ADS)
Ogilvie, Gordon I.
2016-06-01
> These lecture notes and example problems are based on a course given at the University of Cambridge in Part III of the Mathematical Tripos. Fluid dynamics is involved in a very wide range of astrophysical phenomena, such as the formation and internal dynamics of stars and giant planets, the workings of jets and accretion discs around stars and black holes and the dynamics of the expanding Universe. Effects that can be important in astrophysical fluids include compressibility, self-gravitation and the dynamical influence of the magnetic field that is `frozen in' to a highly conducting plasma. The basic models introduced and applied in this course are Newtonian gas dynamics and magnetohydrodynamics (MHD) for an ideal compressible fluid. The mathematical structure of the governing equations and the associated conservation laws are explored in some detail because of their importance for both analytical and numerical methods of solution, as well as for physical interpretation. Linear and nonlinear waves, including shocks and other discontinuities, are discussed. The spherical blast wave resulting from a supernova, and involving a strong shock, is a classic problem that can be solved analytically. Steady solutions with spherical or axial symmetry reveal the physics of winds and jets from stars and discs. The linearized equations determine the oscillation modes of astrophysical bodies, as well as their stability and their response to tidal forcing.
NASA Astrophysics Data System (ADS)
Osawa, Yasuo
New powerful parallel computational tools are developed for 3D simulation of unsteady wake flows with complex geometries and fluid-structure interactions. The base method for flow simulation is a finite element formulation for the Navier-Stokes equations. The finite element formulation is based on the streamline-upwind/Petrov-Galerkin (SUPG) and pressure-stabilizing/Petrov-Galerkin (PSPG) techniques. These stabilization techniques facilitate simulation of flows with high Reynolds numbers, and allow us to use equal-order interpolation functions for velocity and pressure without generating numerical oscillations. A multi-domain computational method is developed to simulate wake flow both in the near and far downstream. The formulations lead to coupled nonlinear equation systems which are solved, at every time step, with the Newton-Raphson method. The overall formulation and solution techniques are implemented on parallel platforms such as the CRAY T3E and SGI PowerChallenge. Two phases of vortex shedding for flow past a cylinder is simulated to verify the accuracy of this method. The Enhanced-Discretization Interface Capturing Technique (EDICT) is utilized to simulate wake flow accurately. Fluid-structure coupling solution method based on the Deforming-Spatial-Domain/Stabilized Space-Time (DSD/SST) formulation is applied to simulate a parachute behavior in the unsteady wake.
Optical-CT 3D Dosimetry Using Fresnel Lenses with Minimal Refractive-Index Matching Fluid
Bache, Steven; Malcolm, Javian; Adamovics, John; Oldham, Mark
2016-01-01
Telecentric optical computed tomography (optical-CT) is a state-of-the-art method for visualizing and quantifying 3-dimensional dose distributions in radiochromic dosimeters. In this work a prototype telecentric system (DFOS—Duke Fresnel Optical-CT Scanner) is evaluated which incorporates two substantial design changes: the use of Fresnel lenses (reducing lens costs from $10-30K t0 $1-3K) and the use of a ‘solid tank’ (which reduces noise, and the volume of refractively matched fluid from 1ltr to 10cc). The efficacy of DFOS was evaluated by direct comparison against commissioned scanners in our lab. Measured dose distributions from all systems were compared against the predicted dose distributions from a commissioned treatment planning system (TPS). Three treatment plans were investigated including a simple four-field box treatment, a multiple small field delivery, and a complex IMRT treatment. Dosimeters were imaged within 2h post irradiation, using consistent scanning techniques (360 projections acquired at 1 degree intervals, reconstruction at 2mm). DFOS efficacy was evaluated through inspection of dose line-profiles, and 2D and 3D dose and gamma maps. DFOS/TPS gamma pass rates with 3%/3mm dose difference/distance-to-agreement criteria ranged from 89.3% to 92.2%, compared to from 95.6% to 99.0% obtained with the commissioned system. The 3D gamma pass rate between the commissioned system and DFOS was 98.2%. The typical noise rates in DFOS reconstructions were up to 3%, compared to under 2% for the commissioned system. In conclusion, while the introduction of a solid tank proved advantageous with regards to cost and convenience, further work is required to improve the image quality and dose reconstruction accuracy of the new DFOS optical-CT system. PMID:27019460
Optical-CT 3D Dosimetry Using Fresnel Lenses with Minimal Refractive-Index Matching Fluid.
Bache, Steven; Malcolm, Javian; Adamovics, John; Oldham, Mark
2016-01-01
Telecentric optical computed tomography (optical-CT) is a state-of-the-art method for visualizing and quantifying 3-dimensional dose distributions in radiochromic dosimeters. In this work a prototype telecentric system (DFOS-Duke Fresnel Optical-CT Scanner) is evaluated which incorporates two substantial design changes: the use of Fresnel lenses (reducing lens costs from $10-30K t0 $1-3K) and the use of a 'solid tank' (which reduces noise, and the volume of refractively matched fluid from 1 ltr to 10 cc). The efficacy of DFOS was evaluated by direct comparison against commissioned scanners in our lab. Measured dose distributions from all systems were compared against the predicted dose distributions from a commissioned treatment planning system (TPS). Three treatment plans were investigated including a simple four-field box treatment, a multiple small field delivery, and a complex IMRT treatment. Dosimeters were imaged within 2 h post irradiation, using consistent scanning techniques (360 projections acquired at 1 degree intervals, reconstruction at 2mm). DFOS efficacy was evaluated through inspection of dose line-profiles, and 2D and 3D dose and gamma maps. DFOS/TPS gamma pass rates with 3%/3mm dose difference/distance-to-agreement criteria ranged from 89.3% to 92.2%, compared to from 95.6% to 99.0% obtained with the commissioned system. The 3D gamma pass rate between the commissioned system and DFOS was 98.2%. The typical noise rates in DFOS reconstructions were up to 3%, compared to under 2% for the commissioned system. In conclusion, while the introduction of a solid tank proved advantageous with regards to cost and convenience, further work is required to improve the image quality and dose reconstruction accuracy of the new DFOS optical-CT system.
Optical-CT 3D Dosimetry Using Fresnel Lenses with Minimal Refractive-Index Matching Fluid.
Bache, Steven; Malcolm, Javian; Adamovics, John; Oldham, Mark
2016-01-01
Telecentric optical computed tomography (optical-CT) is a state-of-the-art method for visualizing and quantifying 3-dimensional dose distributions in radiochromic dosimeters. In this work a prototype telecentric system (DFOS-Duke Fresnel Optical-CT Scanner) is evaluated which incorporates two substantial design changes: the use of Fresnel lenses (reducing lens costs from $10-30K t0 $1-3K) and the use of a 'solid tank' (which reduces noise, and the volume of refractively matched fluid from 1 ltr to 10 cc). The efficacy of DFOS was evaluated by direct comparison against commissioned scanners in our lab. Measured dose distributions from all systems were compared against the predicted dose distributions from a commissioned treatment planning system (TPS). Three treatment plans were investigated including a simple four-field box treatment, a multiple small field delivery, and a complex IMRT treatment. Dosimeters were imaged within 2 h post irradiation, using consistent scanning techniques (360 projections acquired at 1 degree intervals, reconstruction at 2mm). DFOS efficacy was evaluated through inspection of dose line-profiles, and 2D and 3D dose and gamma maps. DFOS/TPS gamma pass rates with 3%/3mm dose difference/distance-to-agreement criteria ranged from 89.3% to 92.2%, compared to from 95.6% to 99.0% obtained with the commissioned system. The 3D gamma pass rate between the commissioned system and DFOS was 98.2%. The typical noise rates in DFOS reconstructions were up to 3%, compared to under 2% for the commissioned system. In conclusion, while the introduction of a solid tank proved advantageous with regards to cost and convenience, further work is required to improve the image quality and dose reconstruction accuracy of the new DFOS optical-CT system. PMID:27019460
NASA Astrophysics Data System (ADS)
Doyle, Andrew D.; Carvajal, Nicole; Jin, Albert; Matsumoto, Kazue; Yamada, Kenneth M.
2015-11-01
The physical properties of two-dimensional (2D) extracellular matrices (ECMs) modulate cell adhesion dynamics and motility, but little is known about the roles of local microenvironmental differences in three-dimensional (3D) ECMs. Here we generate 3D collagen gels of varying matrix microarchitectures to characterize their regulation of 3D adhesion dynamics and cell migration. ECMs containing bundled fibrils demonstrate enhanced local adhesion-scale stiffness and increased adhesion stability through balanced ECM/adhesion coupling, whereas highly pliable reticular matrices promote adhesion retraction. 3D adhesion dynamics are locally regulated by ECM rigidity together with integrin/ECM association and myosin II contractility. Unlike 2D migration, abrogating contractility stalls 3D migration regardless of ECM pore size. We find force is not required for clustering of activated integrins on 3D native collagen fibrils. We propose that efficient 3D migration requires local balancing of contractility with ECM stiffness to stabilize adhesions, which facilitates the detachment of activated integrins from ECM fibrils.
Doyle, Andrew D; Carvajal, Nicole; Jin, Albert; Matsumoto, Kazue; Yamada, Kenneth M
2015-01-01
The physical properties of two-dimensional (2D) extracellular matrices (ECMs) modulate cell adhesion dynamics and motility, but little is known about the roles of local microenvironmental differences in three-dimensional (3D) ECMs. Here we generate 3D collagen gels of varying matrix microarchitectures to characterize their regulation of 3D adhesion dynamics and cell migration. ECMs containing bundled fibrils demonstrate enhanced local adhesion-scale stiffness and increased adhesion stability through balanced ECM/adhesion coupling, whereas highly pliable reticular matrices promote adhesion retraction. 3D adhesion dynamics are locally regulated by ECM rigidity together with integrin/ECM association and myosin II contractility. Unlike 2D migration, abrogating contractility stalls 3D migration regardless of ECM pore size. We find force is not required for clustering of activated integrins on 3D native collagen fibrils. We propose that efficient 3D migration requires local balancing of contractility with ECM stiffness to stabilize adhesions, which facilitates the detachment of activated integrins from ECM fibrils. PMID:26548801
Doyle, Andrew D.; Carvajal, Nicole; Jin, Albert; Matsumoto, Kazue; Yamada, Kenneth M.
2015-01-01
The physical properties of two-dimensional (2D) extracellular matrices (ECMs) modulate cell adhesion dynamics and motility, but little is known about the roles of local microenvironmental differences in three-dimensional (3D) ECMs. Here we generate 3D collagen gels of varying matrix microarchitectures to characterize their regulation of 3D adhesion dynamics and cell migration. ECMs containing bundled fibrils demonstrate enhanced local adhesion-scale stiffness and increased adhesion stability through balanced ECM/adhesion coupling, whereas highly pliable reticular matrices promote adhesion retraction. 3D adhesion dynamics are locally regulated by ECM rigidity together with integrin/ECM association and myosin II contractility. Unlike 2D migration, abrogating contractility stalls 3D migration regardless of ECM pore size. We find force is not required for clustering of activated integrins on 3D native collagen fibrils. We propose that efficient 3D migration requires local balancing of contractility with ECM stiffness to stabilize adhesions, which facilitates the detachment of activated integrins from ECM fibrils. PMID:26548801
PFLOW: A 3-D Numerical Modeling Tool for Calculating Fluid-Pressure Diffusion from Coulomb Strain
NASA Astrophysics Data System (ADS)
Wolf, L. W.; Lee, M.; Meir, A.; Dyer, G.; Ma, K.; Chan, C.
2009-12-01
A new 3D time-dependent pore-pressure diffusion model PFLOW is developed to investigate the response of pore fluids to the crustal deformation generated by strong earthquakes in heterogeneous geologic media. Given crustal strain generated by changes in Coulomb stress, this MATLAB-based code uses Skempton's coefficient to calculate resulting changes fluid pressure. Pore-pressure diffusion can be tracked over time in a user-defined model space with user-prescribed Neumann or Dirchilet boundary conditions and with spatially variable values of permeability. PFLOW employs linear or quadratic finite elements for spatial discretization and first order or second order, explicit or implicit finite difference discretization in time. PFLOW is easily interfaced with output from deformation modeling programs such as Coulomb (Toda et al., 2007) or 3D-DEF (Gomberg and Ellis, 1994). The code is useful for investigating to first-order the evolution of pore pressure changes induced by changes in Coulomb stress and their possible relation to water-level changes in wells or changes in stream discharge. It can also be used for student research and classroom instruction. As an example application, we calculate the coseismic pore pressure changes and diffusion induced by volumetric strain associated with the 1999 Chi-Chi earthquake (Mw = 7.6) in Taiwan. The Chi-Chi earthquake provides an unique opportunity to investigate the spatial and time-dependent poroelastic response of near-field rocks and sediments because there exist extensive observational data of water-level changes and crustal deformation. The integrated model allows us to explore whether changes in Coulomb stress can adequately explain hydrologic anomalies observed in areas such as Taiwan’s western foothills and the Choshui River alluvial plain. To calculate coseismic strain, we use the carefully calibrated finite fault-rupture model of Ma et al. (2005) and the deformation modeling code Coulomb 3.1 (Toda et al., 2007
Investigation of Dynamic Crack Coalescence Using a Gypsum-Like 3D Printing Material
NASA Astrophysics Data System (ADS)
Jiang, Chao; Zhao, Gao-Feng; Zhu, Jianbo; Zhao, Yi-Xin; Shen, Luming
2016-10-01
Dynamic crack coalescence attracts great attention in rock mechanics. However, specimen preparation in experimental study is a time-consuming and difficult procedure. In this work, a gypsum-like material by powder bed and inkjet 3D printing technique was applied to produce specimens with preset cracks for split Hopkinson pressure bar (SHPB) test. From micro X-ray CT test, it was found that the 3D printing technique could successfully prepare specimens that contain preset cracks with width of 0.2 mm. Basic mechanical properties of the 3D printing material, i.e., the elastic modulus, the Poisson's ratio, the density, the compressive strength, the indirect tensile strength, and the fracture toughness, were obtained and reported. Unlike 3D printed specimens using polylactic acid, these gypsum-like specimens can produce failure patterns much closer to those observed in classical rock mechanical tests. Finally, the dynamic crack coalescence of the 3D printed specimens with preset cracks were captured using a high-speed camera during SHPB tests. Failure patterns of these 3D printed specimens are similar to the specimens made by Portland cement concrete. Our results indicate that sample preparation by 3D printing is highly competitive due to its quickness in prototyping, precision and flexibility on the geometry, and high material homogeneity.
NASA Astrophysics Data System (ADS)
Yang, Xiaofeng; Ghafourian, Pegah; Sharma, Puneet; Salman, Khalil; Martin, Diego; Fei, Baowei
2012-02-01
We have applied image analysis methods in the assessment of human kidney perfusion based on 3D dynamic contrast-enhanced (DCE) MRI data. This approach consists of 3D non-rigid image registration of the kidneys and fuzzy C-mean classification of kidney tissues. The proposed registration method reduced motion artifacts in the dynamic images and improved the analysis of kidney compartments (cortex, medulla, and cavities). The dynamic intensity curves show the successive transition of the contrast agent through kidney compartments. The proposed method for motion correction and kidney compartment classification may be used to improve the validity and usefulness of further model-based pharmacokinetic analysis of kidney function.
Parallel contact detection algorithm for transient solid dynamics simulations using PRONTO3D
Attaway, S.W.; Hendrickson, B.A.; Plimpton, S.J.
1996-09-01
An efficient, scalable, parallel algorithm for treating material surface contacts in solid mechanics finite element programs has been implemented in a modular way for MIMD parallel computers. The serial contact detection algorithm that was developed previously for the transient dynamics finite element code PRONTO3D has been extended for use in parallel computation by devising a dynamic (adaptive) processor load balancing scheme.
Hack, C E; Paardekooper, J; Hannema, A J
1986-02-12
The influence of C3 levels on the determination of C3d in plasma and synovial fluid by radial immunodiffusion was investigated. In the method used, C3 is precipitated by 11% polyethylene glycol (PEG), and C3d is measured in the supernatant. In 51 healthy donors, a weak though significant correlation between C3 and C3d levels was found. The mean concentration of C3d was 1.6% of that in aged serum from healthy donors. So, small amounts of C3 (i.e., 1-2% of the normal plasma level) in the 11% PEG supernatants may contribute significantly to the C3d levels measured. A radioimmunoassay that detects C3, C3b, iC3b and C3c was used to measure C3 levels in the PEG supernatants. In PEG supernatants of 4 plasma samples, 0.3-0.6% of the C3 level in normal plasma was found, whereas in those of 2 synovial fluids much higher levels were found (4-10% of the normal plasma level). When purified 125I-labeled antibodies against C3c were added to the gel of the radial immunodiffusion, C3c antigen was detected in the precipitation rings obtained with all PEG supernatants of plasma samples from patients. Therefore, the quantitative contribution of C3 to the precipitation rings in the C3d radial immunodiffusion was analyzed after the addition of an excess of anti-C3c antibodies to the gel. No effect on the size of the C3d-precipitation rings obtained with plasma samples from patients was observed. However, the C3d precipitation rings obtained with synovial fluids were significantly smaller when the gel used in the radial immunodiffusion contained an excess of anti-C3c antibodies together with the anti-C3d serum. We conclude that it is necessary to add an excess of anti-C3c antibodies to the gel used for the radial immunodiffusion, for the determination of C3d levels in synovial fluid. An antiserum against human C3b, which contains both anti-C3c and anti-C3d antibodies, can be used for this purpose.
Chen, Qian
2008-01-01
The generation, motion, and interaction of dislocations play key roles during the plastic deformation process of crystalline solids. 3D Dislocation Dynamics has been employed as a mesoscale simulation algorithm to investigate the collective and cooperative behavior of dislocations. Most current research on 3D Dislocation Dynamics is based on the solutions available in the framework of classical isotropic elasticity. However, due to some degree of elastic anisotropy in almost all crystalline solids, it is very necessary to extend 3D Dislocation Dynamics into anisotropic elasticity. In this study, first, the details of efficient and accurate incorporation of the fully anisotropic elasticity into 3D discrete Dislocation Dynamics by numerically evaluating the derivatives of Green's functions are described. Then the intrinsic properties of perfect dislocations, including their stability, their core properties and disassociation characteristics, in newly discovered rare earth-based intermetallics and in conventional intermetallics are investigated, within the framework of fully anisotropic elasticity supplemented with the atomistic information obtained from the ab initio calculations. Moreover, the evolution and interaction of dislocations in these intermetallics as well as the role of solute segregation are presented by utilizing fully anisotropic 3D dislocation dynamics. The results from this work clearly indicate the role and the importance of elastic anisotropy on the evolution of dislocation microstructures, the overall ductility and the hardening behavior in these systems.
3D Dynamics of Freshwater Lenses in the Near-Surface Layer of the Tropical Ocean
NASA Astrophysics Data System (ADS)
Soloviev, Alexander; Dean, Cayla
2015-04-01
Convective rains in the Intertropical Convergence Zone (ITCZ) produce lenses of freshened water on the ocean surface. These lenses are localized in space and typically involve both salinity and temperature anomalies. Due to significant density anomalies, strong pressure gradients develop, which result in lateral spreading of freshwater lenses in a form resembling gravity currents. Gravity currents inherently involve three-dimensional dynamics. As a type of organized structure, gravity currents in the upper layer of the ocean may also interact with, and be shaped by, the ambient oceanic environment and atmospheric conditions. Among the important factors are the background stratification, wind stress, wind/wave mixing and spatially coherent organized motions in the near-surface layer of the ocean. Under certain conditions, a resonant interaction between a propagating freshwater lens and internal waves in the underlying pycnocline (e.g., barrier layer) may develop, whereas interaction with wind stress may produce an asymmetry in the freshwater lens and associated mixing. These two types of interactions working in concert may explain the series of sharp frontal interfaces, which have been observed in association with freshwater lenses during TOGA COARE. In this work, we have conducted a series of numerical experiments using computational fluid dynamics tools. These numerical simulations were designed to elucidate the relationship between vertical mixing and horizontal advection of salinity under various environmental conditions and potential impact on the Aquarius and SMOS satellite image formation. Available near-surface data from field experiments served as a guidance for numerical simulations. The results of this study indicate that 3D dynamics of freshwater lenses are essential within a certain range of wind/wave conditions and the freshwater influx in the surface layer of the ocean.
NASA Astrophysics Data System (ADS)
Jackson, Derek; Cooper, Andrew; Green, Andrew; Beyers, Meiring; Wiles, Errol; Benallack, Keegan
2016-04-01
Un-vegetated dune fields provide excellent opportunities to examine airflow dynamics over various types and scales of dune landforms. The three dimensional surface over which lower boundary layers travel, help adjust surface airflow and consequently the aeolian response of the dunes themselves. The use of computational fluid dynamic (CFD) modelling in recent studies now enables investigation of the 3D behaviour of airflow over complex terrain, providing new insights into heterogeneous surface flow and aeolian response of dune surfaces on a large (dunefield) scale. Using a largely un-vegetated coastal dune field site at Mpekweni, Eastern Cape, South Africa, a detailed (0.1m gridded) terrestrial laser scanning survey was conducted to create a high resolution topographical surface. Using local wind flow measurements and local met station records as input, CFD modelling was performed for a number of scenarios involving variable direction and magnitude to examine surface flow patterns across multiple dune forms. Near surface acceleration, expansion and separation of airflow inducing convergence and divergence (steering) of flow velocity streamlines are investigated. Flow acceleration over dune crests/brink lines is a key parameter in driving dune migration and slip face dynamics. Dune aspect ratio (height to length) is also important in determining the degree of crestal flow acceleration, with an increase in flow associated with increasing aspect ratios. Variations in dune height appear to be the most important parameter in driving general flow acceleration. The results from the study provide new insights into dune migration behaviour at this site as well as surface flow behaviour across multiple dune configurations and length scales within un-vegetated dune fields.
Costa, Pedro F; Hutmacher, Dietmar W; Theodoropoulos, Christina; Gomes, Manuela E; Reis, Rui L; Vaquette, Cédryck
2015-04-22
The ability to test large arrays of cell and biomaterial combinations in 3D environments is still rather limited in the context of tissue engineering and regenerative medicine. This limitation can be generally addressed by employing highly automated and reproducible methodologies. This study reports on the development of a highly versatile and upscalable method based on additive manufacturing for the fabrication of arrays of scaffolds, which are enclosed into individualized perfusion chambers. Devices containing eight scaffolds and their corresponding bioreactor chambers are simultaneously fabricated utilizing a dual extrusion additive manufacturing system. To demonstrate the versatility of the concept, the scaffolds, while enclosed into the device, are subsequently surface-coated with a biomimetic calcium phosphate layer by perfusion with simulated body fluid solution. 96 scaffolds are simultaneously seeded and cultured with human osteoblasts under highly controlled bidirectional perfusion dynamic conditions over 4 weeks. Both coated and noncoated resulting scaffolds show homogeneous cell distribution and high cell viability throughout the 4 weeks culture period and CaP-coated scaffolds result in a significantly increased cell number. The methodology developed in this work exemplifies the applicability of additive manufacturing as a tool for further automation of studies in the field of tissue engineering and regenerative medicine.
Fluid Flow Processes Study: from a 3D seismic data set in the Pointer Ridge offshore SW Taiwan
NASA Astrophysics Data System (ADS)
Han, Wei-Chung; Liu, Char-Shine; Chen, Liwen; Chi, Wu-Cheng; Lin, Che-Chuan
2016-04-01
This study analyzes a 3D seismic cube in the Pointer Ridge for understanding the fluid flow processes in subsurface. Pointer Ridge is a ridge situated on the passive China continental margin and is suggested as a potential prospect for future gas hydrate development. High methane flux rate, active gas venting and seismic chimneys have been observed in this area, which are direct evidences for active ongoing fluid migration processes. To find the possible fluid conduits and to understand how the fluids have migrated along those conduits, we firstly identify the structural and sedimentary features from this 3D seismic cube in our study area. Secondly, seismic attribute analyses are carried out for detecting fluid conduits and evaluating the contribution of recognized faults/fractures for fluid flow, respectively. Finally, we propose conceptual models to illustrate how fluids have migrated along those conduits to the seafloor and how those conduits have developed. The results show: 1) a major NE-SW striking normal fault (PR Fault) separates a depositional field on the hanging wall and a erosional field on the footwall; 2) the PR Fault zone itself and the chimneys in its footwall act as main conduits for focused fluid flow migrating to the seafloor; 3) the development of the chimneys in the Pointer Ridge area are highly controlled by the erosion and deposition processes. Since the ongoing fluid flow processes will increase the seafloor instabilities and the Pointer Ridge is a gas hydrate leaking site, our results could provide useful information for further risk evaluation.
Real-time visualization of 3-D dynamic microscopic objects using optical diffraction tomography.
Kim, Kyoohyun; Kim, Kyung Sang; Park, Hyunjoo; Ye, Jong Chul; Park, Yongkeun
2013-12-30
3-D refractive index (RI) distribution is an intrinsic bio-marker for the chemical and structural information about biological cells. Here we develop an optical diffraction tomography technique for the real-time reconstruction of 3-D RI distribution, employing sparse angle illumination and a graphic processing unit (GPU) implementation. The execution time for the tomographic reconstruction is 0.21 s for 96(3) voxels, which is 17 times faster than that of a conventional approach. We demonstrated the real-time visualization capability with imaging the dynamics of Brownian motion of an anisotropic colloidal dimer and the dynamic shape change in a red blood cell upon shear flow.
Fibroblast alignment under interstitial fluid flow using a novel 3-D tissue culture model.
Ng, Chee Ping; Swartz, Melody A
2003-05-01
Interstitial flow is an important component of the microcirculation and interstitial environment, yet its effects on cell organization and tissue architecture are poorly understood, in part due to the lack of in vitro models. To examine the effects of interstitial flow on cell morphology and matrix remodeling, we developed a tissue culture model that physically supports soft tissue cultures and allows microscopic visualization of cells within the three-dimensional matrix. In addition, pressure-flow relationships can be continuously monitored to evaluate the bulk hydraulic resistance as an indicator of changes in the overall matrix integrity. We observed that cells such as human dermal fibroblasts aligned perpendicular to the direction of interstitial flow. In contrast, fibroblasts in static three-dimensional controls remained randomly oriented, whereas cells subjected to fluid shear as a two-dimensional monolayer regressed. Also, the dynamic measurements of hydraulic conductivity suggest reorganization toward a steady state. These primary findings help establish the importance of interstitial flow on the biology of tissue organization and interstitial fluid balance. PMID:12531726
XML-based 3D model visualization and simulation framework for dynamic models
NASA Astrophysics Data System (ADS)
Kim, Taewoo; Fishwick, Paul A.
2002-07-01
Relatively recent advances in computer technology enable us to create three-dimensional (3D) dynamic models and simulate them within a 3D web environment. The use of such models is especially valuable when teaching simulation, and the concepts behind dynamic models, since the models are made more accessible to the students. Students tend to enjoy a construction process in which they are able to employ their own cultural and aesthetic forms. The challenge is to create a language that allows for a grammar for modeling, while simultaneously permitting arbitrary presentation styles. For further flexibility, we need an effective way to represent and simulate dynamic models that can be shared by modelers over the Internet. We present an Extensible Markup Language (XML)-based framework that will guide a modeler in creating personalized 3D models, visualizing its dynamic behaviors, and simulating the created models. A model author will use XML files to represent geometries and topology of a dynamic model. Model Fusion Engine, written in Extensible Stylesheet Language Transformation (XSLT), expedites the modeling process by automating the creation of dynamic models with the user-defined XML files. Modelers can also link simulation programs with a created model to analyze the characteristics of the model. The advantages of this system lie in the education of modeling and simulating dynamic models, and in the exploitation of visualizing the dynamic model behaviors.
Massively Parallel Linear Stability Analysis with P_ARPACK for 3D Fluid Flow Modeled with MPSalsa
Lehoucq, R.B.; Salinger, A.G.
1998-10-13
We are interested in the stability of three-dimensional fluid flows to small dkturbances. One computational approach is to solve a sequence of large sparse generalized eigenvalue problems for the leading modes that arise from discretizating the differential equations modeling the flow. The modes of interest are the eigenvalues of largest real part and their associated eigenvectors. We discuss our work to develop an effi- cient and reliable eigensolver for use by the massively parallel simulation code MPSalsa. MPSalsa allows simulation of complex 3D fluid flow, heat transfer, and mass transfer with detailed bulk fluid and surface chemical reaction kinetics.
3D dynamic simulation of crack propagation in extracorporeal shock wave lithotripsy
NASA Astrophysics Data System (ADS)
Wijerathne, M. L. L.; Hori, Muneo; Sakaguchi, Hide; Oguni, Kenji
2010-06-01
Some experimental observations of Shock Wave Lithotripsy(SWL), which include 3D dynamic crack propagation, are simulated with the aim of reproducing fragmentation of kidney stones with SWL. Extracorporeal shock wave lithotripsy (ESWL) is the fragmentation of kidney stones by focusing an ultrasonic pressure pulse onto the stones. 3D models with fine discretization are used to accurately capture the high amplitude shear shock waves. For solving the resulting large scale dynamic crack propagation problem, PDS-FEM is used; it provides numerically efficient failure treatments. With a distributed memory parallel code of PDS-FEM, experimentally observed 3D photoelastic images of transient stress waves and crack patterns in cylindrical samples are successfully reproduced. The numerical crack patterns are in good agreement with the experimental ones, quantitatively. The results shows that the high amplitude shear waves induced in solid, by the lithotriptor generated shock wave, play a dominant role in stone fragmentation.
Fluid dynamics of heart development.
Santhanakrishnan, Arvind; Miller, Laura A
2011-09-01
The morphology, muscle mechanics, fluid dynamics, conduction properties, and molecular biology of the developing embryonic heart have received much attention in recent years due to the importance of both fluid and elastic forces in shaping the heart as well as the striking relationship between the heart's evolution and development. Although few studies have directly addressed the connection between fluid dynamics and heart development, a number of studies suggest that fluids may play a key role in morphogenic signaling. For example, fluid shear stress may trigger biochemical cascades within the endothelial cells of the developing heart that regulate chamber and valve morphogenesis. Myocardial activity generates forces on the intracardiac blood, creating pressure gradients across the cardiac wall. These pressures may also serve as epigenetic signals. In this article, the fluid dynamics of the early stages of heart development is reviewed. The relevant work in cardiac morphology, muscle mechanics, regulatory networks, and electrophysiology is also reviewed in the context of intracardial fluid dynamics. PMID:21327946
Trans3D: a free tool for dynamical visualization of EEG activity transmission in the brain.
Blinowski, Grzegorz; Kamiński, Maciej; Wawer, Dariusz
2014-08-01
The problem of functional connectivity in the brain is in the focus of attention nowadays, since it is crucial for understanding information processing in the brain. A large repertoire of measures of connectivity have been devised, some of them being capable of estimating time-varying directed connectivity. Hence, there is a need for a dedicated software tool for visualizing the propagation of electrical activity in the brain. To this aim, the Trans3D application was developed. It is an open access tool based on widely available libraries and supporting both Windows XP/Vista/7(™), Linux and Mac environments. Trans3D can create animations of activity propagation between electrodes/sensors, which can be placed by the user on the scalp/cortex of a 3D model of the head. Various interactive graphic functions for manipulating and visualizing components of the 3D model and input data are available. An application of the Trans3D tool has helped to elucidate the dynamics of the phenomena of information processing in motor and cognitive tasks, which otherwise would have been very difficult to observe. Trans3D is available at: http://www.eeg.pl/.
NASA Technical Reports Server (NTRS)
Bancroft, Gregory N.; Sikavitsas, Vassilios I.; van den Dolder, Juliette; Sheffield, Tiffany L.; Ambrose, Catherine G.; Jansen, John A.; Mikos, Antonios G.; McIntire, L. V. (Principal Investigator)
2002-01-01
Bone is a complex highly structured mechanically active 3D tissue composed of cellular and matrix elements. The true biological environment of a bone cell is thus derived from a dynamic interaction between responsively active cells experiencing mechanical forces and a continuously changing 3D matrix architecture. To investigate this phenomenon in vitro, marrow stromal osteoblasts were cultured on 3D scaffolds under flow perfusion with different rates of flow for an extended period to permit osteoblast differentiation and significant matrix production and mineralization. With all flow conditions, mineralized matrix production was dramatically increased over statically cultured constructs with the total calcium content of the cultured scaffolds increasing with increasing flow rate. Flow perfusion induced de novo tissue modeling with the formation of pore-like structures in the scaffolds and enhanced the distribution of cells and matrix throughout the scaffolds. These results represent reporting of the long-term effects of fluid flow on primary differentiating osteoblasts and indicate that fluid flow has far-reaching effects on osteoblast differentiation and phenotypic expression in vitro. Flow perfusion culture permits the generation and study of a 3D, actively modeled, mineralized matrix and can therefore be a valuable tool for both bone biology and tissue engineering.
Computational 3D fluid-structure interaction for the aortic valve
NASA Astrophysics Data System (ADS)
Luo, Haoxiang; Chen, Ye; Sun, Wei
2015-11-01
Three-dimensional fluid-structure interaction (FSI) involving large deformations of flexible bodies is common in biological systems. A typical example is the heart valves. Accurate and efficient numerical approaches for modeling such systems are still lacking. In this work, we report a successful case of combining an immersed-boundary flow solver with a nonlinear finite-element solid-dynamics solver, both in-house programs, specifically for three-dimensional simulations. Based on the Cartesian grid, the viscous incompressible flow solver can handle boundaries of large displacements with simple mesh generation. The solid-dynamics solver has separate subroutines for analyzing general three-dimensional bodies and thin-walled structures composed of frames, membranes, and plates. Both geometric nonlinearity associated with large displacements and material nonlinearity associated with large strains are incorporated in the solver. The FSI is achieved through a strong coupling and partitioned approach. We have performed several benchmarking cases to validate the FSI solver. Application to the native aortic valve will be demonstrated. Supported by the NSF grant (CBET-1066962).
Effect of Ductile Agents on the Dynamic Behavior of SiC3D Network Composites
NASA Astrophysics Data System (ADS)
Zhu, Jingbo; Wang, Yangwei; Wang, Fuchi; Fan, Qunbo
2016-07-01
Co-continuous SiC ceramic composites using pure aluminum, epoxy, and polyurethane (PU) as ductile agents were developed. The dynamic mechanical behavior and failure mechanisms were investigated experimentally using the split Hopkinson pressure bar (SHPB) method and computationally by finite element (FE) simulations. The results show that the SiC3D/Al composite has the best overall performance in comparison with SiC3D/epoxy and SiC3D/PU composites. FE simulations are generally consistent with experimental data. These simulations provide valuable help in predicting mechanical strength and in interpreting the experimental results and failure mechanisms. They may be combined with micrographs for fracture characterizations of the composites. We found that interactions between the SiC phase and ductile agents under dynamic compression in the SHPB method are complex, and that interfacial condition is an important parameter that determines the mechanical response of SiC3D composites with a characteristic interlocking structure during dynamic compression. However, the effect of the mechanical properties of ductile agents on dynamic behavior of the composites is a second consideration in the production of the composites.
ERIC Educational Resources Information Center
Berney, Sandra; Bétrancourt, Mireille; Molinari, Gaëlle; Hoyek, Nady
2015-01-01
The emergence of dynamic visualizations of three-dimensional (3D) models in anatomy curricula may be an adequate solution for spatial difficulties encountered with traditional static learning, as they provide direct visualization of change throughout the viewpoints. However, little research has explored the interplay between learning material…
3D-dynamic graphs as a classification tool of DNA sequences
NASA Astrophysics Data System (ADS)
WaÌ§Ż, P.; Bielińska-WaÌ§Ż, D.
2016-10-01
A method, called 3D-dynamic representation of DNA sequences, and its application to the classification of the DNA sequences is briefly reviewed. Some new classification diagrams obtained using this method are also shown. The method constitutes an alignment free tool of the comparison of the DNA sequences. It allows for both graphical and numerical similarity/dissimilarity analysis of the sequences.
Effect of Ductile Agents on the Dynamic Behavior of SiC3D Network Composites
NASA Astrophysics Data System (ADS)
Zhu, Jingbo; Wang, Yangwei; Wang, Fuchi; Fan, Qunbo
2016-10-01
Co-continuous SiC ceramic composites using pure aluminum, epoxy, and polyurethane (PU) as ductile agents were developed. The dynamic mechanical behavior and failure mechanisms were investigated experimentally using the split Hopkinson pressure bar (SHPB) method and computationally by finite element (FE) simulations. The results show that the SiC3D/Al composite has the best overall performance in comparison with SiC3D/epoxy and SiC3D/PU composites. FE simulations are generally consistent with experimental data. These simulations provide valuable help in predicting mechanical strength and in interpreting the experimental results and failure mechanisms. They may be combined with micrographs for fracture characterizations of the composites. We found that interactions between the SiC phase and ductile agents under dynamic compression in the SHPB method are complex, and that interfacial condition is an important parameter that determines the mechanical response of SiC3D composites with a characteristic interlocking structure during dynamic compression. However, the effect of the mechanical properties of ductile agents on dynamic behavior of the composites is a second consideration in the production of the composites.
3D Flow Visualization Using Texture Advection
NASA Technical Reports Server (NTRS)
Kao, David; Zhang, Bing; Kim, Kwansik; Pang, Alex; Moran, Pat (Technical Monitor)
2001-01-01
Texture advection is an effective tool for animating and investigating 2D flows. In this paper, we discuss how this technique can be extended to 3D flows. In particular, we examine the use of 3D and 4D textures on 3D synthetic and computational fluid dynamics flow fields.
Sketch on dynamic gesture tracking and analysis exploiting vision-based 3D interface
NASA Astrophysics Data System (ADS)
Woo, Woontack; Kim, Namgyu; Wong, Karen; Tadenuma, Makoto
2000-12-01
In this paper, we propose a vision-based 3D interface exploiting invisible 3D boxes, arranged in the personal space (i.e. reachable space by the body without traveling), which allows robust yet simple dynamic gesture tracking and analysis, without exploiting complicated sensor-based motion tracking systems. Vision-based gesture tracking and analysis is still a challenging problem, even though we have witnessed rapid advances in computer vision over the last few decades. The proposed framework consists of three main parts, i.e. (1) object segmentation without bluescreen and 3D box initialization with depth information, (2) movement tracking by observing how the body passes through the 3D boxes in the personal space and (3) movement feature extraction based on Laban's Effort theory and movement analysis by mapping features to meaningful symbols using time-delay neural networks. Obviously, exploiting depth information using multiview images improves the performance of gesture analysis by reducing the errors introduced by simple 2D interfaces In addition, the proposed box-based 3D interface lessens the difficulties in both tracking movement in 3D space and in extracting low-level features of the movement. Furthermore, the time-delay neural networks lessens the difficulties in movement analysis by training. Due to its simplicity and robustness, the framework will provide interactive systems, such as ATR I-cubed Tangible Music System or ATR Interactive Dance system, with improved quality of the 3D interface. The proposed simple framework also can be extended to other applications requiring dynamic gesture tracking and analysis on the fly.
Tunesi, Marta; Fusco, Federica; Fiordaliso, Fabio; Corbelli, Alessandro; Biella, Gloria; Raimondi, Manuela T
2016-01-01
Frontotemporal lobar degeneration (FTLD) is a severe neurodegenerative disorder that is diagnosed with increasing frequency in clinical setting. Currently, no therapy is available and in addition the molecular basis of the disease are far from being elucidated. Consequently, it is of pivotal importance to develop reliable and cost-effective in vitro models for basic research purposes and drug screening. To this respect, recent results in the field of Alzheimer's disease have suggested that a tridimensional (3D) environment is an added value to better model key pathologic features of the disease. Here, we have tried to add complexity to the 3D cell culturing concept by using a microfluidic bioreactor, where cells are cultured under a continuous flow of medium, thus mimicking the interstitial fluid movement that actually perfuses the body tissues, including the brain. We have implemented this model using a neuronal-like cell line (SH-SY5Y), a widely exploited cell model for neurodegenerative disorders that shows some basic features relevant for FTLD modeling, such as the release of the FTLD-related protein progranulin (PRGN) in specific vesicles (exosomes). We have efficiently seeded the cells on 3D scaffolds, optimized a disease-relevant oxidative stress experiment (by targeting mitochondrial function that is one of the possible FTLD-involved pathological mechanisms) and evaluated cell metabolic activity in dynamic culture in comparison to static conditions, finding that SH-SY5Y cells cultured in 3D scaffold are susceptible to the oxidative damage triggered by a mitochondrial-targeting toxin (6-OHDA) and that the same cells cultured in dynamic conditions kept their basic capacity to secrete PRGN in exosomes once recovered from the bioreactor and plated in standard 2D conditions. We think that a further improvement of our microfluidic system may help in providing a full device where assessing basic FTLD-related features (including PRGN dynamic secretion) that may be
Tunesi, Marta; Fusco, Federica; Fiordaliso, Fabio; Corbelli, Alessandro; Biella, Gloria; Raimondi, Manuela T
2016-01-01
Frontotemporal lobar degeneration (FTLD) is a severe neurodegenerative disorder that is diagnosed with increasing frequency in clinical setting. Currently, no therapy is available and in addition the molecular basis of the disease are far from being elucidated. Consequently, it is of pivotal importance to develop reliable and cost-effective in vitro models for basic research purposes and drug screening. To this respect, recent results in the field of Alzheimer's disease have suggested that a tridimensional (3D) environment is an added value to better model key pathologic features of the disease. Here, we have tried to add complexity to the 3D cell culturing concept by using a microfluidic bioreactor, where cells are cultured under a continuous flow of medium, thus mimicking the interstitial fluid movement that actually perfuses the body tissues, including the brain. We have implemented this model using a neuronal-like cell line (SH-SY5Y), a widely exploited cell model for neurodegenerative disorders that shows some basic features relevant for FTLD modeling, such as the release of the FTLD-related protein progranulin (PRGN) in specific vesicles (exosomes). We have efficiently seeded the cells on 3D scaffolds, optimized a disease-relevant oxidative stress experiment (by targeting mitochondrial function that is one of the possible FTLD-involved pathological mechanisms) and evaluated cell metabolic activity in dynamic culture in comparison to static conditions, finding that SH-SY5Y cells cultured in 3D scaffold are susceptible to the oxidative damage triggered by a mitochondrial-targeting toxin (6-OHDA) and that the same cells cultured in dynamic conditions kept their basic capacity to secrete PRGN in exosomes once recovered from the bioreactor and plated in standard 2D conditions. We think that a further improvement of our microfluidic system may help in providing a full device where assessing basic FTLD-related features (including PRGN dynamic secretion) that may be
Stellar Astrophysical Fluid Dynamics
NASA Astrophysics Data System (ADS)
Thompson, Michael J.; Christensen-Dalsgaard, Jørgen
2003-05-01
Preface; 1. A selective overview Jørgen Christensen-Dalsgaard and Michael J. Thompson; Part I. Stellar Convection and Oscillations: 2. On the diversity of stellar pulsations Wojciech A. Dziembowski; 3. Acoustic radiation and mode excitation by turbulent convection Günter Houdek; 4. Understanding roAp stars Margarida S. Cunha; 5. Waves in the magnetised solar atmosphere Colin S. Rosenthal; Part II. Stellar Rotation and Magnetic Fields: 6. Stellar rotation: a historical survey Leon Mestel; 7. The oscillations of rapidly rotating stars Michel Rieutord; 8. Solar tachocline dynamics: eddy viscosity, anti-friction, or something in between? Michael E. McIntyre; 9. Dynamics of the solar tachocline Pascale Garaud; 10. Dynamo processes: the interaction of turbulence and magnetic fields Michael Proctor; 11. Dynamos in planets Chris Jones; Part III. Physics and Structure of Stellar Interiors: 12. Solar constraints on the equation of state Werner Däppen; 13. 3He transport and the solar neutrino problem Chris Jordinson; 14. Mixing in stellar radiation zones Jean-Paul Zahn; 15. Element settling and rotation-induced mixing in slowly rotating stars Sylvie Vauclair; Part IV. Helio- and Asteroseismology: 16. Solar structure and the neutrino problem Hiromoto Shibahashi; 17. Helioseismic data analysis Jesper Schou; 18. Seismology of solar rotation Takashi Sekii; 19. Telechronohelioseismology Alexander Kosovichev; Part V. Large-Scale Numerical Experiments: 20. Bridges between helioseismology and models of convection zone dynamics Juri Toomre; 21. Numerical simulations of the solar convection zone Julian R. Elliott; 22. Modelling solar and stellar magnetoconvection Nigel Weiss; 23. Nonlinear magnetoconvection in the presence of a strong oblique field Keith Julien, Edgar Knobloch and Steven M. Tobias; 24. Simulations of astrophysical fluids Marcus Brüggen; Part VI. Dynamics: 25. A magic electromagnetic field Donald Lynden-Bell; 26. Continuum equations for stellar dynamics Edward A
Stellar Astrophysical Fluid Dynamics
NASA Astrophysics Data System (ADS)
Thompson, Michael J.; Christensen-Dalsgaard, Jørgen
2008-02-01
Preface; 1. A selective overview Jørgen Christensen-Dalsgaard and Michael J. Thompson; Part I. Stellar Convection and Oscillations: 2. On the diversity of stellar pulsations Wojciech A. Dziembowski; 3. Acoustic radiation and mode excitation by turbulent convection Günter Houdek; 4. Understanding roAp stars Margarida S. Cunha; 5. Waves in the magnetised solar atmosphere Colin S. Rosenthal; Part II. Stellar Rotation and Magnetic Fields: 6. Stellar rotation: a historical survey Leon Mestel; 7. The oscillations of rapidly rotating stars Michel Rieutord; 8. Solar tachocline dynamics: eddy viscosity, anti-friction, or something in between? Michael E. McIntyre; 9. Dynamics of the solar tachocline Pascale Garaud; 10. Dynamo processes: the interaction of turbulence and magnetic fields Michael Proctor; 11. Dynamos in planets Chris Jones; Part III. Physics and Structure of Stellar Interiors: 12. Solar constraints on the equation of state Werner Däppen; 13. 3He transport and the solar neutrino problem Chris Jordinson; 14. Mixing in stellar radiation zones Jean-Paul Zahn; 15. Element settling and rotation-induced mixing in slowly rotating stars Sylvie Vauclair; Part IV. Helio- and Asteroseismology: 16. Solar structure and the neutrino problem Hiromoto Shibahashi; 17. Helioseismic data analysis Jesper Schou; 18. Seismology of solar rotation Takashi Sekii; 19. Telechronohelioseismology Alexander Kosovichev; Part V. Large-Scale Numerical Experiments: 20. Bridges between helioseismology and models of convection zone dynamics Juri Toomre; 21. Numerical simulations of the solar convection zone Julian R. Elliott; 22. Modelling solar and stellar magnetoconvection Nigel Weiss; 23. Nonlinear magnetoconvection in the presence of a strong oblique field Keith Julien, Edgar Knobloch and Steven M. Tobias; 24. Simulations of astrophysical fluids Marcus Brüggen; Part VI. Dynamics: 25. A magic electromagnetic field Donald Lynden-Bell; 26. Continuum equations for stellar dynamics Edward A
Compressible Magma/Mantle Dynamics: 3d, Adaptive Simulations in ASPECT
NASA Astrophysics Data System (ADS)
Dannberg, Juliane; Heister, Timo
2016-09-01
Melt generation and migration are an important link between surface processes and the thermal and chemical evolution of the Earth's interior. However, their vastly different time scales make it difficult to study mantle convection and melt migration in a unified framework, especially for three-dimensional, global models. And although experiments suggest an increase in melt volume of up to 20% from the depth of melt generation to the surface, previous computations have neglected the individual compressibilities of the solid and the fluid phase. Here, we describe our extension of the finite element mantle convection code ASPECT that adds melt generation and migration. We use the original compressible formulation of the McKenzie equations, augmented by an equation for the conservation of energy. Applying adaptive mesh refinement to this type of problems is particularly advantageous, as the resolution can be increased in areas where melt is present and viscosity gradients are high, whereas a lower resolution is sufficient in regions without melt. Together with a high-performance, massively parallel implementation, this allows for high resolution, 3d, compressible, global mantle convection simulations coupled with melt migration. We evaluate the functionality and potential of this method using a series of benchmarks and model setups, compare results of the compressible and incompressible formulation, and show the effectiveness of adaptive mesh refinement when applied to melt migration. Our model of magma dynamics provides a framework for modelling processes on different scales and investigating links between processes occurring in the deep mantle and melt generation and migration. This approach could prove particularly useful applied to modelling the generation of komatiites or other melts originating in greater depths. The implementation is available in the Open Source ASPECT repository.
Computational fluid dynamic applications
Chang, S.-L.; Lottes, S. A.; Zhou, C. Q.
2000-04-03
The rapid advancement of computational capability including speed and memory size has prompted the wide use of computational fluid dynamics (CFD) codes to simulate complex flow systems. CFD simulations are used to study the operating problems encountered in system, to evaluate the impacts of operation/design parameters on the performance of a system, and to investigate novel design concepts. CFD codes are generally developed based on the conservation laws of mass, momentum, and energy that govern the characteristics of a flow. The governing equations are simplified and discretized for a selected computational grid system. Numerical methods are selected to simplify and calculate approximate flow properties. For turbulent, reacting, and multiphase flow systems the complex processes relating to these aspects of the flow, i.e., turbulent diffusion, combustion kinetics, interfacial drag and heat and mass transfer, etc., are described in mathematical models, based on a combination of fundamental physics and empirical data, that are incorporated into the code. CFD simulation has been applied to a large variety of practical and industrial scale flow systems.
NASA Astrophysics Data System (ADS)
Meqbel, Naser; Weckmann, Ute; Muñoz, Gerard; Ritter, Oliver
2016-09-01
We report on a study to explore the deep electrical conductivity structure of the Dead Sea Basin (DSB) using magnetotelluric (MT) data collected along a transect across the DSB where the left lateral strike slip Dead Sea transform fault (DST) splits into two fault strands forming one of the largest pull-apart basins of the world. A very pronounced feature of our 2D inversion model is a deep, sub-vertical conductive zone beneath the DSB. The conductor extends through the entire crust and is sandwiched between highly resistive structures associated with Precambrian rocks of the basin flanks. The high electrical conductivity could be attributed to fluids released by dehydration of the uppermost mantle beneath the DSB, possibly in combination with fluids released by mid to low grade metamorphism in the lower crust and generation of hydrous minerals in the middle crust through retrograde metamorphism. Similar high conductivity zones associated with fluids have been reported from other large fault systems. The presence of fluids and hydrous minerals in the middle and lower crust could explain the required low friction coefficient of the DST along the eastern boundary of the Dead Sea basin and the high subsidence rate of basin sediments. 3D inversion models confirm the existence of a sub-vertical high conductivity structure underneath the DSB but its expression is far less pronounced. Instead, the 3D inversion model suggests a deepening of the conductive DSB sediments off-profile towards the south, reaching a maximum depth of approximately 12 km, which is consistent with other geophysical observations. At shallower levels, the 3D inversion model reveals salt diapirism as an upwelling of highly resistive structures, localized underneath the Al-Lisan Peninsula. The 3D model furthermore contains an E-W elongated conductive structure to the north-east of the Dead Sea basin. More MT data with better spatial coverage are required, however, to fully constrain the robustness of
Predictions of bubbly flows in vertical pipes using two-fluid models in CFDS-FLOW3D code
Banas, A.O.; Carver, M.B.; Unrau, D.
1995-09-01
This paper reports the results of a preliminary study exploring the performance of two sets of two-fluid closure relationships applied to the simulation of turbulent air-water bubbly upflows through vertical pipes. Predictions obtained with the default CFDS-FLOW3D model for dispersed flows were compared with the predictions of a new model (based on the work of Lee), and with the experimental data of Liu. The new model, implemented in the CFDS-FLOW3D code, included additional source terms in the {open_quotes}standard{close_quotes} {kappa}-{epsilon} transport equations for the liquid phase, as well as modified model coefficients and wall functions. All simulations were carried out in a 2-D axisymmetric format, collapsing the general multifluid framework of CFDS-FLOW3D to the two-fluid (air-water) case. The newly implemented model consistently improved predictions of radial-velocity profiles of both phases, but failed to accurately reproduce the experimental phase-distribution data. This shortcoming was traced to the neglect of anisotropic effects in the modelling of liquid-phase turbulence. In this sense, the present investigation should be considered as the first step toward the ultimate goal of developing a theoretically sound and universal CFD-type two-fluid model for bubbly flows in channels.
Santee, G.E. Jr.; Chang, F.H.; Mortensen, G.A.; Brockett, G.F.; Gross, M.B.; Belytschko, T.B.
1982-11-01
This report, the third in a series of reports for RP-1065, describes the final step in the stepwise approach for developing the three-dimensional, nonlinear, fluid-structure interaction methodology to assess the hydroloads on a large PWR during the subcooled portions of a hypothetical LOCA. The final step in the methodology implements enhancements and special modifications to the STEALTH 3D computer program and the WHAMSE 3D computer program. After describing the enhancements, the individual and the coupled computer programs are assessed by comparing calculational results with either analytical solutions or with experimental data. The coupled 3D STEALTH/WHAMSE computer program is then applied to the simulation of HDR Test V31.1 to further assess the program and to investigate the role that fluid-structure interaction plays in the hydrodynamic loading of reactor internals during subcooled blowdown.
Progress in the Peeling-Ballooning Model of ELMs: Numerical Studies of 3D Nonlinear ELM Dynamics
Snyder, P B; Wilson, H R; Xu, X Q
2004-12-13
Nonlinear simulations with the 3D electromagnetic two-fluid BOUT code are employed to study the dynamics of edge localized modes (ELMs) driven by intermediate wavelength peeling-ballooning modes. It is found that the early behavior of the modes is similar to expectations from linear, ideal peeling-ballooning mode theory, with the modes growing linearly at a fraction of the Alfven frequency. In the non-linear phase, the modes grow explosively, forming a number of extended filaments which propagate rapidly from the outer closed flux region into the open flux region toward the outer wall. Similarities to non-linear linear ballooning theory, as well as additional complexities are observed. Comparison to observations reveals a number of similarities. Implications of the simulations and proposals for the dynamics of the full ELM crash are discussed.
PROGRESS IN THE PEELING-BALLOONING MODEL OF ELMS: NUMERICAL STUDIES OF 3D NONLINEAR ELM DYNAMICS
SNYDER,P.B; WILSON,H.R; XU,X.Q
2004-11-01
Nonlinear simulations with the 3D electromagnetic two-fluid BOUT code are employed to study the dynamics of edge localized modes (ELMs) driven by intermediate wavelength peeling-ballooning modes. It is found that the early behavior of the modes is similar to expectations from linear, ideal peeling-ballooning mode theory, with the modes growing linearly at a fraction of the Alfven frequency. In the nonlinear phase, the modes grow explosively, forming a number of extended filaments which propagate rapidly from the outer closed flux region into the open flux region toward the outboard wall. Similarities to non-linear ballooning theory, as well as additional complexities are observed. Comparison to observations reveals a number of similarities. Implications of the simulations and proposals for the dynamics of the full ELM crash are discussed.
Zhang, A Ping; Qu, Xin; Soman, Pranav; Hribar, Kolin C; Lee, Jin W; Chen, Shaochen; He, Sailing
2012-08-16
The topographic features of the extracelluar matrix (ECM) lay the foundation for cellular behavior. A novel biofabrication method using a digital-mirror device (DMD), called dynamic optical projection stereolithography (DOPsL) is demonstrated. This robust and versatile platform can generate complex biomimetic scaffolds within seconds. Such 3D scaffolds have promising potentials for studying cell interactions with microenvironments in vitro and in vivo.
From 2D Mesoscale Surface Expressions to 3D Upper Ocean Dynamics
NASA Astrophysics Data System (ADS)
Johannessen, J. A.; Chapron, B.; Kudryavtsev, V.; Collard, F.
2013-03-01
This paper discusses the establishment of a new framework for synergetic use of satellite data. The motivation is to advance the understanding and ability to more consistently transfer the 2-dimensional (2D) satellite observations of the surface expressions of mesoscale to submesoscale features in the upper ocean to 3D upper ocean dynamics. This will strongly capitalize on both existing and approved high resolution and coarser resolution satellite data in synergy with high quality in-situ data and reliable ocean models.
Real-Time Modeling and 3D Visualization of Source Dynamics and Connectivity Using Wearable EEG
Mullen, Tim; Kothe, Christian; Chi, Yu Mike; Ojeda, Alejandro; Kerth, Trevor; Makeig, Scott; Cauwenberghs, Gert; Jung, Tzyy-Ping
2014-01-01
This report summarizes our recent efforts to deliver real-time data extraction, preprocessing, artifact rejection, source reconstruction, multivariate dynamical system analysis (including spectral Granger causality) and 3D visualization as well as classification within the open-source SIFT and BCILAB toolboxes. We report the application of such a pipeline to simulated data and real EEG data obtained from a novel wearable high-density (64-channel) dry EEG system. PMID:24110155
Computational Fluid Dynamics Technology for Hypersonic Applications
NASA Technical Reports Server (NTRS)
Gnoffo, Peter A.
2003-01-01
Several current challenges in computational fluid dynamics and aerothermodynamics for hypersonic vehicle applications are discussed. Example simulations are presented from code validation and code benchmarking efforts to illustrate capabilities and limitations. Opportunities to advance the state-of-art in algorithms, grid generation and adaptation, and code validation are identified. Highlights of diverse efforts to address these challenges are then discussed. One such effort to re-engineer and synthesize the existing analysis capability in LAURA, VULCAN, and FUN3D will provide context for these discussions. The critical (and evolving) role of agile software engineering practice in the capability enhancement process is also noted.
PRONTO3D users` instructions: A transient dynamic code for nonlinear structural analysis
Attaway, S.W.; Mello, F.J.; Heinstein, M.W.; Swegle, J.W.; Ratner, J.A.; Zadoks, R.I.
1998-06-01
This report provides an updated set of users` instructions for PRONTO3D. PRONTO3D is a three-dimensional, transient, solid dynamics code for analyzing large deformations of highly nonlinear materials subjected to extremely high strain rates. This Lagrangian finite element program uses an explicit time integration operator to integrate the equations of motion. Eight-node, uniform strain, hexahedral elements and four-node, quadrilateral, uniform strain shells are used in the finite element formulation. An adaptive time step control algorithm is used to improve stability and performance in plasticity problems. Hourglass distortions can be eliminated without disturbing the finite element solution using either the Flanagan-Belytschko hourglass control scheme or an assumed strain hourglass control scheme. All constitutive models in PRONTO3D are cast in an unrotated configuration defined using the rotation determined from the polar decomposition of the deformation gradient. A robust contact algorithm allows for the impact and interaction of deforming contact surfaces of quite general geometry. The Smooth Particle Hydrodynamics method has been embedded into PRONTO3D using the contact algorithm to couple it with the finite element method.
Stereoscopic 3D display with dynamic optical correction for recovering from asthenopia
NASA Astrophysics Data System (ADS)
Shibata, Takashi; Kawai, Takashi; Otsuki, Masaki; Miyake, Nobuyuki; Yoshihara, Yoshihiro; Iwasaki, Tsuneto
2005-03-01
The purpose of this study was to consider a practical application of a newly developed stereoscopic 3-D display that solves the problem of discrepancy between accommodation and convergence. The display uses dynamic optical correction to reduce the discrepancy, and can present images as if they are actually remote objects. The authors thought the display may assist in recovery from asthenopia, which is often caused when the eyes focus on a nearby object for a long time, such as in VDT (Visual Display Terminal) work. In general, recovery from asthenopia, and especially accommodative asthenopia, is achieved by focusing on distant objects. In order to verify this hypothesis, the authors performed visual acuity tests using Landolt rings before and after presenting stereoscopic 3-D images, and evaluated the degree of recovery from asthenopia. The experiment led to three main conclusions: (1) Visual acuity rose after viewing stereoscopic 3-D images on the developed display. (2) Recovery from asthenopia was particularly effective for the dominant eye in comparison with the other eye. (3) Interviews with the subjects indicated that the Landolt rings were particularly clear after viewing the stereoscopic 3-D images.
Examination of asthenopia recovery using stereoscopic 3D display with dynamic optical correction
NASA Astrophysics Data System (ADS)
Shibata, Takashi; Kawai, Takashi; Ohta, Keiji; Lee, JaeLin; Otsuki, Masaki; Miyake, Nobuyuki; Yoshihara, Yoshihiro; Iwasaki, Tsuneto
2006-02-01
A common cause of asthenopia is viewing objects from a short distance, as is the case when working at a VDT (Visual Display Terminal). In general, recovery from asthenopia, especially accommodative asthenopia, is aided by looking into the distance. The authors have developed a stereoscopic 3-D display with dynamic optical correction that may reduce asthenopia. The display does this by reducing the discrepancy between accommodation and convergence, thereby presenting images as if they were actually in the distance. The results of visual acuity tests given before and after presenting stereoscopic 3-D images with this display show a tendency towards less asthenopia. In this study, the authors developed a refraction feedback function that makes the viewer's distance vision more effective when viewing stereoscopic 3-D images on the this display. Using this function, refraction is fed back during viewing and the viewer gradually acquires distance vision. The results of the study suggest that stereoscopic 3-D images are more effective than 2-D images for recovery from asthenopia.
Can symmetry transitions of complex fields enable 3-d control of fluid vorticity?
Martin, James E.; Solis, Kyle Jameson
2015-08-01
Methods of inducing vigorous noncontact fluid flow are important to technologies involving heat and mass transfer and fluid mixing, since they eliminate the need for moving parts, pipes and seals, all of which compromise system reliability. Unfortunately, traditional noncontact flow methods are few, and have limitations of their own. We have discovered two classes of fields that can induce fluid vorticity without requiring either gravity or a thermal gradient. The first class we call Symmetry-Breaking Rational Fields. These are triaxial fields comprised of three orthogonal components, two ac and one dc. The second class is Rational Triad Fields, which differ in that all three components are alternating. In this report we quantify the induced vorticity for a wide variety of fields and consider symmetry transitions between these field types. These transitions give rise to orbiting vorticity vectors, a technology for non-contact, non-stationary fluid mixing.
Bedwell, A E; Elson, C J; Carter, S D; Dieppe, P A; Hutton, C W; Czudek, R
1987-01-01
The complement activating aggregates in synovial fluids of patients with rheumatoid arthritis (RA) have been isolated using monoclonal IgM anti-C3d antibodies attached to solid phases, and the content of the material bound has been analysed. High levels of aggregated IgG bearing C3d were found in RA synovial fluids, and IgG was the major immunoglobulin bound from such synovial fluids by anti-C3d Sepharose. A strong correlation was shown between levels of aggregated IgG bearing C3d and complement activation, as judged by C3d levels. Significant (but less strong) relationships were also observed between C3d levels and both complement consuming and C1q binding activity. C3d levels and levels of aggregated IgG bearing C3d were both significantly associated with the numbers of polymorphonuclear leucocytes (PMNs) found in RA synovial fluids. From these results it is concluded that the aggregated immunoglobulins bearing C3d (particularly IgG) isolated from RA synovial fluids are responsible for activating complement and attracting PMNs into the joint space. Radioimmunoassay showed no correlation, however, between levels of aggregated IgG (or IgM) bearing C3d and rheumatoid factor (RF) activity bound by anti-C3d. In addition, the material bound by anti-C3d Sepharose from most synovial fluid polyethylene glycol precipitates did not contain either IgM or IgG RF. Thus both techniques show that the majority of complexes bearing C3d do not contain RF. As the complement fixing aggregates apparently contain only immunoglobulin and complement components the results raise the problem of how the aggregates are formed. It is suggested that RA IgG may remain aggregated after either antigen or antibody (RF) has dissociated from the complex. Images PMID:3492971
Dynamic WIFI-Based Indoor Positioning in 3D Virtual World
NASA Astrophysics Data System (ADS)
Chan, S.; Sohn, G.; Wang, L.; Lee, W.
2013-11-01
A web-based system based on the 3DTown project was proposed using Google Earth plug-in that brings information from indoor positioning devices and real-time sensors into an integrated 3D indoor and outdoor virtual world to visualize the dynamics of urban life within the 3D context of a city. We addressed limitation of the 3DTown project with particular emphasis on video surveillance camera used for indoor tracking purposes. The proposed solution was to utilize wireless local area network (WLAN) WiFi as a replacement technology for localizing objects of interest due to the wide spread availability and large coverage area of WiFi in indoor building spaces. Indoor positioning was performed using WiFi without modifying existing building infrastructure or introducing additional access points (AP)s. A hybrid probabilistic approach was used for indoor positioning based on previously recorded WiFi fingerprint database in the Petrie Science and Engineering building at York University. In addition, we have developed a 3D building modeling module that allows for efficient reconstruction of outdoor building models to be integrated with indoor building models; a sensor module for receiving, distributing, and visualizing real-time sensor data; and a web-based visualization module for users to explore the dynamic urban life in a virtual world. In order to solve the problems in the implementation of the proposed system, we introduce approaches for integration of indoor building models with indoor positioning data, as well as real-time sensor information and visualization on the web-based system. In this paper we report the preliminary results of our prototype system, demonstrating the system's capability for implementing a dynamic 3D indoor and outdoor virtual world that is composed of discrete modules connected through pre-determined communication protocols.
Fluid Dynamics with Free Surfaces
1992-02-01
RIPPLE is a two-dimensional, transient, free surface incompressible fluid dynamics program. It allows multiple free surfaces with surface tension and wall adhesion forces and has a partial cell treatment which allows curved boundaries and interior obstacles.
The Variety of Fluid Dynamics.
ERIC Educational Resources Information Center
Barnes, Francis; And Others
1980-01-01
Discusses three research topics which are concerned with eminently practical problems and deal at the same time with fundamental fluid dynamical problems. These research topics come from the general areas of chemical and biological engineering, geophysics, and pure mathematics. (HM)
Berney, Sandra; Bétrancourt, Mireille; Molinari, Gaëlle; Hoyek, Nady
2015-01-01
The emergence of dynamic visualizations of three-dimensional (3D) models in anatomy curricula may be an adequate solution for spatial difficulties encountered with traditional static learning, as they provide direct visualization of change throughout the viewpoints. However, little research has explored the interplay between learning material presentation formats, spatial abilities, and anatomical tasks. First, to understand the cognitive challenges a novice learner would be faced with when first exposed to 3D anatomical content, a six-step cognitive task analysis was developed. Following this, an experimental study was conducted to explore how presentation formats (dynamic vs. static visualizations) support learning of functional anatomy, and affect subsequent anatomical tasks derived from the cognitive task analysis. A second aim was to investigate the interplay between spatial abilities (spatial visualization and spatial relation) and presentation formats when the functional anatomy of a 3D scapula and the associated shoulder flexion movement are learned. Findings showed no main effect of the presentation formats on performances, but revealed the predictive influence of spatial visualization and spatial relation abilities on performance. However, an interesting interaction between presentation formats and spatial relation ability for a specific anatomical task was found. This result highlighted the influence of presentation formats when spatial abilities are involved as well as the differentiated influence of spatial abilities on anatomical tasks.
Using articulated scene models for dynamic 3d scene analysis in vista spaces
NASA Astrophysics Data System (ADS)
Beuter, Niklas; Swadzba, Agnes; Kummert, Franz; Wachsmuth, Sven
2010-09-01
In this paper we describe an efficient but detailed new approach to analyze complex dynamic scenes directly in 3D. The arising information is important for mobile robots to solve tasks in the area of household robotics. In our work a mobile robot builds an articulated scene model by observing the environment in the visual field or rather in the so-called vista space. The articulated scene model consists of essential knowledge about the static background, about autonomously moving entities like humans or robots and finally, in contrast to existing approaches, information about articulated parts. These parts describe movable objects like chairs, doors or other tangible entities, which could be moved by an agent. The combination of the static scene, the self-moving entities and the movable objects in one articulated scene model enhances the calculation of each single part. The reconstruction process for parts of the static scene benefits from removal of the dynamic parts and in turn, the moving parts can be extracted more easily through the knowledge about the background. In our experiments we show, that the system delivers simultaneously an accurate static background model, moving persons and movable objects. This information of the articulated scene model enables a mobile robot to detect and keep track of interaction partners, to navigate safely through the environment and finally, to strengthen the interaction with the user through the knowledge about the 3D articulated objects and 3D scene analysis. [Figure not available: see fulltext.
Härmä, Ville; Schukov, Hannu-Pekka; Happonen, Antti; Ahonen, Ilmari; Virtanen, Johannes; Siitari, Harri; Åkerfelt, Malin; Lötjönen, Jyrki; Nees, Matthias
2014-01-01
Glandular epithelial cells differentiate into complex multicellular or acinar structures, when embedded in three-dimensional (3D) extracellular matrix. The spectrum of different multicellular morphologies formed in 3D is a sensitive indicator for the differentiation potential of normal, non-transformed cells compared to different stages of malignant progression. In addition, single cells or cell aggregates may actively invade the matrix, utilizing epithelial, mesenchymal or mixed modes of motility. Dynamic phenotypic changes involved in 3D tumor cell invasion are sensitive to specific small-molecule inhibitors that target the actin cytoskeleton. We have used a panel of inhibitors to demonstrate the power of automated image analysis as a phenotypic or morphometric readout in cell-based assays. We introduce a streamlined stand-alone software solution that supports large-scale high-content screens, based on complex and organotypic cultures. AMIDA (Automated Morphometric Image Data Analysis) allows quantitative measurements of large numbers of images and structures, with a multitude of different spheroid shapes, sizes, and textures. AMIDA supports an automated workflow, and can be combined with quality control and statistical tools for data interpretation and visualization. We have used a representative panel of 12 prostate and breast cancer lines that display a broad spectrum of different spheroid morphologies and modes of invasion, challenged by a library of 19 direct or indirect modulators of the actin cytoskeleton which induce systematic changes in spheroid morphology and differentiation versus invasion. These results were independently validated by 2D proliferation, apoptosis and cell motility assays. We identified three drugs that primarily attenuated the invasion and formation of invasive processes in 3D, without affecting proliferation or apoptosis. Two of these compounds block Rac signalling, one affects cellular cAMP/cGMP accumulation. Our approach supports
NASA Astrophysics Data System (ADS)
Jung, Jaewoon; Kobayashi, Chigusa; Imamura, Toshiyuki; Sugita, Yuji
2016-03-01
Three-dimensional Fast Fourier Transform (3D FFT) plays an important role in a wide variety of computer simulations and data analyses, including molecular dynamics (MD) simulations. In this study, we develop hybrid (MPI+OpenMP) parallelization schemes of 3D FFT based on two new volumetric decompositions, mainly for the particle mesh Ewald (PME) calculation in MD simulations. In one scheme, (1d_Alltoall), five all-to-all communications in one dimension are carried out, and in the other, (2d_Alltoall), one two-dimensional all-to-all communication is combined with two all-to-all communications in one dimension. 2d_Alltoall is similar to the conventional volumetric decomposition scheme. We performed benchmark tests of 3D FFT for the systems with different grid sizes using a large number of processors on the K computer in RIKEN AICS. The two schemes show comparable performances, and are better than existing 3D FFTs. The performances of 1d_Alltoall and 2d_Alltoall depend on the supercomputer network system and number of processors in each dimension. There is enough leeway for users to optimize performance for their conditions. In the PME method, short-range real-space interactions as well as long-range reciprocal-space interactions are calculated. Our volumetric decomposition schemes are particularly useful when used in conjunction with the recently developed midpoint cell method for short-range interactions, due to the same decompositions of real and reciprocal spaces. The 1d_Alltoall scheme of 3D FFT takes 4.7 ms to simulate one MD cycle for a virus system containing more than 1 million atoms using 32,768 cores on the K computer.
Radial electric field 3D modeling for wire arrays driving dynamic hohlraums on Z.
Mock, Raymond Cecil
2007-06-01
The anode-cathode structure of the Z-machine wire array results in a higher negative radial electric field (Er) on the wires near the cathode relative to the anode. The magnitude of this field has been shown to anti-correlate with the axial radiation top/bottom symmetry in the DH (Dynamic Hohlraum). Using 3D modeling, the structure of this field is revealed for different wire-array configurations and for progressive mechanical alterations, providing insight for minimizing the negative Er on the wire array in the anode-to-cathode region of the DH. Also, the 3D model is compared to Sasorov's approximation, which describes Er at the surface of the wire in terms of wire-array parameters.
Blob Dynamics in 3D BOUT Simulations of Tokamak Edge Turbulence
Russell, D; D'Ippolito, D; Myra, J; Nevins, W; Xu, X
2004-08-23
Propagating filaments of enhanced plasma density, or blobs, observed in 3D numerical simulations of a diverted, neutral-fueled tokamak are studied. Fluctuations of vorticity, electrical potential {phi}, temperature T{sub e} and current density J{sub {parallel}} associated with the blobs have a dipole structure perpendicular to the magnetic field and propagate radially with large E {center_dot} B drift velocities (> 1 km/s). The simulation results are consistent with a 3D blob dynamics model that incorporates increased parallel plasma resistivity (from neutral cooling of the X-point region), blob disconnection from the divertor sheath, X-point closure of the current loops, and collisional physics to sustain the {phi}, T{sub e}, J{sub {parallel}} dipoles.
The computer simulation of 3d gas dynamics in a gas centrifuge
NASA Astrophysics Data System (ADS)
Borman, V. D.; Bogovalov, S. V.; Borisevich, V. D.; Tronin, I. V.; Tronin, V. N.
2016-09-01
We argue on the basis of the results of 2D analysis of the gas flow in gas centrifuges that a reliable calculation of the circulation of the gas and gas content in the gas centrifuge is possible only in frameworks of 3D numerical simulation of gas dynamics in the gas centrifuge (hereafter GC). The group from National research nuclear university, MEPhI, has created a computer code for 3D simulation of the gas flow in GC. The results of the computer simulations of the gas flows in GC are presented. A model Iguassu centrifuge is explored for the simulations. A nonaxisymmetric gas flow is produced due to interaction of the hypersonic rotating flow with the scoops for extraction of the product and waste flows from the GC. The scoops produce shock waves penetrating into a working camera of the GC and form spiral waves there.
Hand Gesture Spotting Based on 3D Dynamic Features Using Hidden Markov Models
NASA Astrophysics Data System (ADS)
Elmezain, Mahmoud; Al-Hamadi, Ayoub; Michaelis, Bernd
In this paper, we propose an automatic system that handles hand gesture spotting and recognition simultaneously in stereo color image sequences without any time delay based on Hidden Markov Models (HMMs). Color and 3D depth map are used to segment hand regions. The hand trajectory will determine in further step using Mean-shift algorithm and Kalman filter to generate 3D dynamic features. Furthermore, k-means clustering algorithm is employed for the HMMs codewords. To spot meaningful gestures accurately, a non-gesture model is proposed, which provides confidence limit for the calculated likelihood by other gesture models. The confidence measures are used as an adaptive threshold for spotting meaningful gestures. Experimental results show that the proposed system can successfully recognize isolated gestures with 98.33% and meaningful gestures with 94.35% reliability for numbers (0-9).
Nonlinear dynamics of Airy-vortex 3D wave packets: emission of vortex light waves.
Driben, Rodislav; Meier, Torsten
2014-10-01
The dynamics of 3D Airy-vortex wave packets is studied under the action of strong self-focusing Kerr nonlinearity. Emissions of nonlinear 3D waves out of the main wave packets with the topological charges were demonstrated. Because of the conservation of the total angular momentum, charges of the emitted waves are equal to those carried by the parental light structure. The rapid collapse imposes a severe limitation on the propagation of multidimensional waves in Kerr media. However, the structure of the Airy beam carrier allows the coupling of light from the leading, most intense peak into neighboring peaks and consequently strongly postpones the collapse. The dependence of the critical input amplitude for the appearance of a fast collapse on the beam width is studied for wave packets with zero and nonzero topological charges. Wave packets carrying angular momentum are found to be much more resistant to the rapid collapse.
User's manuals for DYNA3D and DYNAP: nonlinear dynamic analysis of solids in three dimensions
Hallquist, J.O.
1981-07-01
This report provides a user's manual for DYNA3D, an explicit three-dimensional finite element code for analyzing the large deformation dynamic response of inelastic solids. A contact-impact algorithm permits gaps and sliding along material interfaces. By a specialization of this algorithm, such interfaces can be rigidly tied to admit variable zoning without the need of transition regions. Spatial discretization is achieved by the use of 8-node solid elements, and the equations-of-motion are integrated by the central difference method. Post-processors for DYNA3D include GRAPE for plotting deformed shapes and stress contours and DYNAP for plotting time histories. A user's manual for DYNAP is also provided in this report.
Gierke, Sarah; Wittmann, Torsten
2012-01-01
SUMMARY Background Epithelial remodeling, in which apical-basal polarized cells switch to a migratory phenotype, plays a central role in development and disease of multicellular organisms. Although dynamic microtubules (MTs) are required for directed migration on flat surfaces, how MT dynamics are controlled or contribute to epithelial remodeling in a more physiological three-dimensional (3D) environment is not understood. We use confocal live cell imaging to analyze MT function and dynamics during 3D epithelial morphogenesis and remodeling of polarized Madin-Darby canine kidney (MDCK) epithelial cells that undergo partial epithelial-to-mesenchymal transition (EMT) in response to hepatocyte growth factor (HGF). Results We find that HGF treatment increases MT growth rate before morphological changes are evident, and that large numbers of MTs grow into HGF-induced cell extensions independent of centrosome reorientation. Using lentivirus-mediated shRNA, we demonstrate that EB1, an adaptor protein that mediates recruitment of numerous other +TIP proteins to growing MT plus ends, is required for this HGF-induced MT reorganization. We further show that protrusion and adhesion dynamics are disorganized, and that vesicular trafficking to the tip of HGF-induced cell extensions is disrupted in EB1-depleted cells. Conclusions We conclude that EB1-mediated interactions with growing MTs are important to coordinate cell shape changes and directed migration into the surrounding extracellular matrix during epithelial remodeling in a physiological 3D environment. In contrast, EB1 is not required for the establishment or maintenance of apical-basal cell polarity, suggesting different functions of +TIPs and MTs in different types of cell polarity. PMID:22483942
The handbook of fluid dynamics
Johnson, R.W.
1998-07-01
This book provides professionals in the field of fluid dynamics with a comprehensive guide and resource. The book balances three traditional areas of fluid mechanics--theoretical, computational, and experimental--and expounds on basic science and engineering techniques. Each chapter introduces a topic, discusses the primary issues related to this subject, outlines approaches taken by experts, and supplies references for further information. Topics discussed include: (1) basic engineering fluid dynamics; (2) classical fluid dynamics; (3) turbulence modeling; (4) reacting flows; (5) multiphase flows; (6) flow and porous media; (7) high Reynolds number asymptotic theories; (8) finite difference method; (9) finite volume method; (10) finite element methods; (11) spectral element methods for incompressible flows; (12) experimental methods, such as hot-wire anemometry, laser-Doppler velocimetry, and flow visualization; and (13) applications, such as axial-flow compressor and fan aerodynamics, turbomachinery, airfoils and wings, atmospheric flows, and mesoscale oceanic flows.
NASA Technical Reports Server (NTRS)
Gayman, W. H.
1974-01-01
Test method and apparatus determine fluid effective mass and damping in frequency range where effective mass may be considered as total mass less sum of slosh masses. Apparatus is designed so test tank and its mounting yoke are supported from structural test wall by series of flexures.
Quantification of Diaphragm Mechanics in Pompe Disease Using Dynamic 3D MRI
Mogalle, Katja; Perez-Rovira, Adria; Ciet, Pierluigi; Wens, Stephan C. A.; van Doorn, Pieter A.; Tiddens, Harm A. W. M.; van der Ploeg, Ans T.; de Bruijne, Marleen
2016-01-01
Background Diaphragm weakness is the main reason for respiratory dysfunction in patients with Pompe disease, a progressive metabolic myopathy affecting respiratory and limb-girdle muscles. Since respiratory failure is the major cause of death among adult patients, early identification of respiratory muscle involvement is necessary to initiate treatment in time and possibly prevent irreversible damage. In this paper we investigate the suitability of dynamic MR imaging in combination with state-of-the-art image analysis methods to assess respiratory muscle weakness. Methods The proposed methodology relies on image registration and lung surface extraction to quantify lung kinematics during breathing. This allows for the extraction of geometry and motion features of the lung that characterize the independent contribution of the diaphragm and the thoracic muscles to the respiratory cycle. Results Results in 16 3D+t MRI scans (10 Pompe patients and 6 controls) of a slow expiratory maneuver show that kinematic analysis from dynamic 3D images reveals important additional information about diaphragm mechanics and respiratory muscle involvement when compared to conventional pulmonary function tests. Pompe patients with severely reduced pulmonary function showed severe diaphragm weakness presented by minimal motion of the diaphragm. In patients with moderately reduced pulmonary function, cranial displacement of posterior diaphragm parts was reduced and the diaphragm dome was oriented more horizontally at full inspiration compared to healthy controls. Conclusion Dynamic 3D MRI provides data for analyzing the contribution of both diaphragm and thoracic muscles independently. The proposed image analysis method has the potential to detect less severe diaphragm weakness and could thus be used to determine the optimal start of treatment in adult patients with Pompe disease in prospect of increased treatment response. PMID:27391236
Obstacle avoidance using predictive vision based on a dynamic 3D world model
NASA Astrophysics Data System (ADS)
Benjamin, D. Paul; Lyons, Damian; Achtemichuk, Tom
2006-10-01
We have designed and implemented a fast predictive vision system for a mobile robot based on the principles of active vision. This vision system is part of a larger project to design a comprehensive cognitive architecture for mobile robotics. The vision system represents the robot's environment with a dynamic 3D world model based on a 3D gaming platform (Ogre3D). This world model contains a virtual copy of the robot and its environment, and outputs graphics showing what the virtual robot "sees" in the virtual world; this is what the real robot expects to see in the real world. The vision system compares this output in real time with the visual data. Any large discrepancies are flagged and sent to the robot's cognitive system, which constructs a plan for focusing on the discrepancies and resolving them, e.g. by updating the position of an object or by recognizing a new object. An object is recognized only once; thereafter its observed data are monitored for consistency with the predictions, greatly reducing the cost of scene understanding. We describe the implementation of this vision system and how the robot uses it to locate and avoid obstacles.
The 3-D alignment of objects in dynamic PET scans using filtered sinusoidal trajectories of sinogram
NASA Astrophysics Data System (ADS)
Kostopoulos, Aristotelis E.; Happonen, Antti P.; Ruotsalainen, Ulla
2006-12-01
In this study, our goal is to employ a novel 3-D alignment method for dynamic positron emission tomography (PET) scans. Because the acquired data (i.e. sinograms) often contain noise considerably, filtering of the data prior to the alignment presumably improves the final results. In this study, we utilized a novel 3-D stackgram domain approach. In the stackgram domain, the signals along the sinusoidal trajectory signals of the sinogram can be processed separately. In this work, we performed angular stackgram domain filtering by employing well known 1-D filters: the Gaussian low-pass filter and the median filter. In addition, we employed two wavelet de-noising techniques. After filtering we performed alignment of objects in the stackgram domain. The local alignment technique we used is based on similarity comparisons between locus vectors (i.e. the signals along the sinusoidal trajectories of the sinogram) in a 3-D neighborhood of sequences of the stackgrams. Aligned stackgrams can be transformed back to sinograms (Method 1), or alternatively directly to filtered back-projected images (Method 2). In order to evaluate the alignment process, simulated data with different kinds of additive noises were used. The results indicated that the filtering prior to the alignment can be important concerning the accuracy.
NASA Astrophysics Data System (ADS)
Makhfudz, Imam
2016-04-01
Axion electrodynamics, first proposed in the context of particle physics, manifests itself in condensed matter physics in the topological field theory description of 3 d topological insulators and gives rise to magnetoelectric effect, where applying magnetic (electric) field B (E ) induces polarization (magnetization) p (m ) . We use linear response theory to study the associated topological current using the Fu-Kane-Mele model of 3 d topological insulators in the presence of time-dependent uniform weak magnetic field. By computing the dynamical current susceptibility χij jpjp(ω ) , we discover from its static limit an `order parameter' of the topological phase transition between weak topological (or ordinary) insulator and strong topological insulator, found to be continuous. The χij jpjp(ω ) shows a sign-changing singularity at a critical frequency with suppressed strength in the topological insulating state. Our results can be verified in current noise experiment on 3 d TI candidate materials for the detection of such topological phase transition.
Semi-automatic segmentation for 3D motion analysis of the tongue with dynamic MRI.
Lee, Junghoon; Woo, Jonghye; Xing, Fangxu; Murano, Emi Z; Stone, Maureen; Prince, Jerry L
2014-12-01
Dynamic MRI has been widely used to track the motion of the tongue and measure its internal deformation during speech and swallowing. Accurate segmentation of the tongue is a prerequisite step to define the target boundary and constrain the tracking to tissue points within the tongue. Segmentation of 2D slices or 3D volumes is challenging because of the large number of slices and time frames involved in the segmentation, as well as the incorporation of numerous local deformations that occur throughout the tongue during motion. In this paper, we propose a semi-automatic approach to segment 3D dynamic MRI of the tongue. The algorithm steps include seeding a few slices at one time frame, propagating seeds to the same slices at different time frames using deformable registration, and random walker segmentation based on these seed positions. This method was validated on the tongue of five normal subjects carrying out the same speech task with multi-slice 2D dynamic cine-MR images obtained at three orthogonal orientations and 26 time frames. The resulting semi-automatic segmentations of a total of 130 volumes showed an average dice similarity coefficient (DSC) score of 0.92 with less segmented volume variability between time frames than in manual segmentations. PMID:25155697
Dynamics of gecko locomotion: a force-measuring array to measure 3D reaction forces.
Dai, Zhendong; Wang, Zhouyi; Ji, Aihong
2011-03-01
Measuring the interaction between each foot of an animal and the substrate is one of the most effective ways to understand the dynamics of legged locomotion. Here, a new facility - the force-measuring array (FMA) - was developed and applied to measure 3D reaction forces of geckos on different slope surfaces. The FMA consists of 16 3D sensors with resolution to the mN level. At the same time the locomotion behaviour of geckos freely moving on the FMA was recorded by high speed camera. The reaction forces acting on the gecko's individual feet measured by the FMA and correlated with locomotion behaviour provided enough information to reveal the mechanical and dynamic secrets of gecko locomotion. Moreover, dynamic forces were also measured by a force platform and correlated with locomotion behaviour. The difference between the forces measured by the two methods is discussed. From the results we conclude that FMA is the best way to obtain true reaction forces acting on the gecko's individual feet.
Semi-automatic segmentation for 3D motion analysis of the tongue with dynamic MRI.
Lee, Junghoon; Woo, Jonghye; Xing, Fangxu; Murano, Emi Z; Stone, Maureen; Prince, Jerry L
2014-12-01
Dynamic MRI has been widely used to track the motion of the tongue and measure its internal deformation during speech and swallowing. Accurate segmentation of the tongue is a prerequisite step to define the target boundary and constrain the tracking to tissue points within the tongue. Segmentation of 2D slices or 3D volumes is challenging because of the large number of slices and time frames involved in the segmentation, as well as the incorporation of numerous local deformations that occur throughout the tongue during motion. In this paper, we propose a semi-automatic approach to segment 3D dynamic MRI of the tongue. The algorithm steps include seeding a few slices at one time frame, propagating seeds to the same slices at different time frames using deformable registration, and random walker segmentation based on these seed positions. This method was validated on the tongue of five normal subjects carrying out the same speech task with multi-slice 2D dynamic cine-MR images obtained at three orthogonal orientations and 26 time frames. The resulting semi-automatic segmentations of a total of 130 volumes showed an average dice similarity coefficient (DSC) score of 0.92 with less segmented volume variability between time frames than in manual segmentations.
Simulating 3-D lung dynamics using a programmable graphics processing unit.
Santhanam, Anand P; Hamza-Lup, Felix G; Rolland, Jannick P
2007-09-01
Medical simulations of lung dynamics promise to be effective tools for teaching and training clinical and surgical procedures related to lungs. Their effectiveness may be greatly enhanced when visualized in an augmented reality (AR) environment. However, the computational requirements of AR environments limit the availability of the central processing unit (CPU) for the lung dynamics simulation for different breathing conditions. In this paper, we present a method for computing lung deformations in real time by taking advantage of the programmable graphics processing unit (GPU). This will save the CPU time for other AR-associated tasks such as tracking, communication, and interaction management. An approach for the simulations of the three-dimensional (3-D) lung dynamics using Green's formulation in the case of upright position is taken into consideration. We extend this approach to other orientations as well as the subsequent changes in breathing. Specifically, the proposed extension presents a computational optimization and its implementation in a GPU. Results show that the computational requirements for simulating the deformation of a 3-D lung model are significantly reduced for point-based rendering.
Semi-automatic segmentation for 3D motion analysis of the tongue with dynamic MRI
Lee, Junghoon; Woo, Jonghye; Xing, Fangxu; Murano, Emi Z.; Stone, Maureen; Prince, Jerry L.
2014-01-01
Dynamic MRI has been widely used to track the motion of the tongue and measure its internal deformation during speech and swallowing. Accurate segmentation of the tongue is a prerequisite step to define the target boundary and constrain the tracking to tissue points within the tongue. Segmentation of 2D slices or 3D volumes is challenging because of the large number of slices and time frames involved in the segmentation, as well as the incorporation of numerous local deformations that occur throughout the tongue during motion. In this paper, we propose a semi-automatic approach to segment 3D dynamic MRI of the tongue. The algorithm steps include seeding a few slices at one time frame, propagating seeds to the same slices at different time frames using deformable registration, and random walker segmentation based on these seed positions. This method was validated on the tongue of five normal subjects carrying out the same speech task with multi-slice 2D dynamic cine-MR images obtained at three orthogonal orientations and 26 time frames. The resulting semi-automatic segmentations of a total of 130 volumes showed an average dice similarity coefficient (DSC) score of 0.92 with less segmented volume variability between time frames than in manual segmentations. PMID:25155697
Dynamic Characteristics of a Model and Prototype for 3D-RC Structure
NASA Astrophysics Data System (ADS)
Moniuddin, Md. Khaja; Vasanthalakshmi, G.; Chethan, K.; Babu, R. Ramesh
2016-06-01
Infill walls provide durable and economical partitions that have relatively excellent thermal and sound insulation with high fire resistance. Monolithic infilled walls are provided within RC structures without being analyzed as a combination of concrete and brick elements, although in reality they act as a single unit during earthquakes. The performance of such structures during earthquakes has proved to be superior in comparison to bare frames in terms of stiffness, strength and energy dissipation. To know the dynamic characteristics of monolithic infill wall panels and masonry infill, modal, response spectrum and time history analyses have been carried out on a model and prototype of a 3D RC structure for a comparative study.
NASA Astrophysics Data System (ADS)
Kimoto, K.; Hirose, S.
2002-05-01
This paper presents a boundary integral equation method for 3D ultrasonic scattering problems in a fluid-loaded elastic half space. Since full scale of numerical calculation using finite element or boundary element method is still very expensive, we formulate a boundary integral equation for the scattered field, which is amenable to numerical treatment. In order to solve the problem using the integral equation, however, the wave field without scattering objects, so-called free field need to be given in advance. We calculate the free field by the plane wave spectral method where the asymptotic approximation is introduced for computational efficiency. To show the efficiency of our method, scattering by a spherical cavity near fluid-solid interface is solved and the validity of the results is discussed.
Tunesi, Marta; Fusco, Federica; Fiordaliso, Fabio; Corbelli, Alessandro; Biella, Gloria; Raimondi, Manuela T.
2016-01-01
Frontotemporal lobar degeneration (FTLD) is a severe neurodegenerative disorder that is diagnosed with increasing frequency in clinical setting. Currently, no therapy is available and in addition the molecular basis of the disease are far from being elucidated. Consequently, it is of pivotal importance to develop reliable and cost-effective in vitro models for basic research purposes and drug screening. To this respect, recent results in the field of Alzheimer’s disease have suggested that a tridimensional (3D) environment is an added value to better model key pathologic features of the disease. Here, we have tried to add complexity to the 3D cell culturing concept by using a microfluidic bioreactor, where cells are cultured under a continuous flow of medium, thus mimicking the interstitial fluid movement that actually perfuses the body tissues, including the brain. We have implemented this model using a neuronal-like cell line (SH-SY5Y), a widely exploited cell model for neurodegenerative disorders that shows some basic features relevant for FTLD modeling, such as the release of the FTLD-related protein progranulin (PRGN) in specific vesicles (exosomes). We have efficiently seeded the cells on 3D scaffolds, optimized a disease-relevant oxidative stress experiment (by targeting mitochondrial function that is one of the possible FTLD-involved pathological mechanisms) and evaluated cell metabolic activity in dynamic culture in comparison to static conditions, finding that SH-SY5Y cells cultured in 3D scaffold are susceptible to the oxidative damage triggered by a mitochondrial-targeting toxin (6-OHDA) and that the same cells cultured in dynamic conditions kept their basic capacity to secrete PRGN in exosomes once recovered from the bioreactor and plated in standard 2D conditions. We think that a further improvement of our microfluidic system may help in providing a full device where assessing basic FTLD-related features (including PRGN dynamic secretion) that may
Development and validation of a 3-D model to predict knee joint loading during dynamic movement.
McLean, S G; Su, A; van den Bogert, A J
2003-12-01
The purpose of this study was to develop a subject-specific 3-D model of the lower extremity to predict neuromuscular control effects on 3-D knee joint loading during movements that can potentially cause injury to the anterior cruciate ligament (ACL) in the knee. The simulation consisted of a forward dynamic 3-D musculoskeletal model of the lower extremity, scaled to represent a specific subject. Inputs of the model were the initial position and velocity of the skeletal elements, and the muscle stimulation patterns. Outputs of the model were movement and ground reaction forces, as well as resultant 3-D forces and moments acting across the knee joint. An optimization method was established to find muscle stimulation patterns that best reproduced the subject's movement and ground reaction forces during a sidestepping task. The optimized model produced movements and forces that were generally within one standard deviation of the measured subject data. Resultant knee joint loading variables extracted from the optimized model were comparable to those reported in the literature. The ability of the model to successfully predict the subject's response to altered initial conditions was quantified and found acceptable for use of the model to investigate the effect of altered neuromuscular control on knee joint loading during sidestepping. Monte Carlo simulations (N = 100,000) using randomly perturbed initial kinematic conditions, based on the subject's variability, resulted in peak anterior force, valgus torque and internal torque values of 378 N, 94 Nm and 71 Nm, respectively, large enough to cause ACL rupture. We conclude that the procedures described in this paper were successful in creating valid simulations of normal movement, and in simulating injuries that are caused by perturbed neuromuscular control.
Dynamic lens and monovision 3D displays to improve viewer comfort.
Johnson, Paul V; Parnell, Jared Aq; Kim, Joohwan; Saunter, Christopher D; Love, Gordon D; Banks, Martin S
2016-05-30
Stereoscopic 3D (S3D) displays provide an additional sense of depth compared to non-stereoscopic displays by sending slightly different images to the two eyes. But conventional S3D displays do not reproduce all natural depth cues. In particular, focus cues are incorrect causing mismatches between accommodation and vergence: The eyes must accommodate to the display screen to create sharp retinal images even when binocular disparity drives the eyes to converge to other distances. This mismatch causes visual discomfort and reduces visual performance. We propose and assess two new techniques that are designed to reduce the vergence-accommodation conflict and thereby decrease discomfort and increase visual performance. These techniques are much simpler to implement than previous conflict-reducing techniques. The first proposed technique uses variable-focus lenses between the display and the viewer's eyes. The power of the lenses is yoked to the expected vergence distance thereby reducing the mismatch between vergence and accommodation. The second proposed technique uses a fixed lens in front of one eye and relies on the binocularly fused percept being determined by one eye and then the other, depending on simulated distance. We conducted performance tests and discomfort assessments with both techniques and compared the results to those of a conventional S3D display. The first proposed technique, but not the second, yielded clear improvements in performance and reductions in discomfort. This dynamic-lens technique therefore offers an easily implemented technique for reducing the vergence-accommodation conflict and thereby improving viewer experience. PMID:27410105
Lobera, Julia; Ortega, Gloria; García, Inmaculada; Arroyo, María del Pilar; Garzón, Ester M
2015-02-23
Optical Diffraction Tomography has been recently introduced in fluid velocimetry to provide three dimensional information of seeding particle locations. In general, image reconstruction methods at visible wavelengths have to account for diffraction. Linear approximation has been used for three-dimensional image reconstruction, but a non-linear and iterative reconstruction method is required when multiple scattering is not negligible. Non-linear methods require the solution of the Helmholtz equation, computationally highly demanding due to the size of the problem. The present work shows the results of a non-linear method customized for spherical particle location using GPU computing and a made-to-measure storing format.
Insights from 3D numerical simulations on the dynamics of the India-Asia collision zone
NASA Astrophysics Data System (ADS)
Pusok, A. E.; Kaus, B.; Popov, A.
2013-12-01
The dynamics of the India-Asia collision zone remains one of the most remarkable topics of the current research interest: the transition from subduction to collision and uplift, followed by the rise of the abnormally thick Tibetan plateau, and the deformation at its Eastern and Western syntaxes, are processes still not fully understood. Models that have addressed this topic include wholescale underthrusting of Indian lithospheric mantle under Tibet, distributed homogeneous shortening or the thin-sheet model, slip-line field model for lateral extrusion or lower crustal flow models for the exhumation of the Himalayan units and lateral spreading of the Tibetan plateau. Of these, the thin-sheet model has successfully illustrated some of the basic physics of continental collision and has the advantage of a 3D model being reduced to 2D, but one of its major shortcomings is that it cannot simultaneously represent channel flow and gravitational collapse of the mantle lithosphere, since these mechanisms require the lithosphere to interact with the underlying mantle, or to have a vertically non-homogeneous rheology. As a consequence, 3D models are emerging as powerful tools to understand the dynamics of coupled systems. However, because of yet recent developments and various complexities, the current 3D models simulating the dynamics of continent collision zones have relied on certain explicit assumptions, such as replacing part of the asthenosphere with various types of boundary conditions that mimic the effect of mantle flow, in order to focus on the lithospheric/crustal deformation. Here, we employ the parallel 3D code LaMEM (Lithosphere and Mantle Evolution Model), with a finite difference staggered grid solver, which is capable of simulating lithospheric deformation while simultaneously taking mantle flow and a free surface into account. We present qualitative results on lithospheric and upper-mantle scale simulations in which the Indian lithosphere is subducted and
Rapid 3D dynamic arterial spin labeling with a sparse model-based image reconstruction.
Zhao, Li; Fielden, Samuel W; Feng, Xue; Wintermark, Max; Mugler, John P; Meyer, Craig H
2015-11-01
Dynamic arterial spin labeling (ASL) MRI measures the perfusion bolus at multiple observation times and yields accurate estimates of cerebral blood flow in the presence of variations in arterial transit time. ASL has intrinsically low signal-to-noise ratio (SNR) and is sensitive to motion, so that extensive signal averaging is typically required, leading to long scan times for dynamic ASL. The goal of this study was to develop an accelerated dynamic ASL method with improved SNR and robustness to motion using a model-based image reconstruction that exploits the inherent sparsity of dynamic ASL data. The first component of this method is a single-shot 3D turbo spin echo spiral pulse sequence accelerated using a combination of parallel imaging and compressed sensing. This pulse sequence was then incorporated into a dynamic pseudo continuous ASL acquisition acquired at multiple observation times, and the resulting images were jointly reconstructed enforcing a model of potential perfusion time courses. Performance of the technique was verified using a numerical phantom and it was validated on normal volunteers on a 3-Tesla scanner. In simulation, a spatial sparsity constraint improved SNR and reduced estimation errors. Combined with a model-based sparsity constraint, the proposed method further improved SNR, reduced estimation error and suppressed motion artifacts. Experimentally, the proposed method resulted in significant improvements, with scan times as short as 20s per time point. These results suggest that the model-based image reconstruction enables rapid dynamic ASL with improved accuracy and robustness.
NASA Astrophysics Data System (ADS)
Eusemann, Christian D.; Mohlenkamp, Stefan; Ritman, Erik L.; Robb, Richard A.
2001-05-01
Regional heart wall dynamics has been shown to be a sensitive indicator of LV wall ischemia. Rates of local LV wall thickening during a cardiac cycle can be measured and illustrated using functional parametric mappings. This display conveys the spatial distribution of dynamic strain in the myocardium and thereby provides a rapid qualitative appreciation of the severity and extent of the ischemic region. 3D reconstructions were obtained in an anesthetized pig from 8 adjacent, shortaxis, slices of the left ventricle imaged with an Electron Beam Computer Tomograph at 11 time points through one complete cardiac cycle. The 3D reconstructions were obtained before and after injection of 100 micrometer microspheres into the Left Anterior Descending (LAD) coronary artery. This injection causes microembolization of LAD artery branches within the heart wall. The image processing involved radially dividing the tomographic images of the myocardium into small subdivisions with color encoding of the local magnitude of regional thickness or regional velocities of LV wall thickening throughout the cardiac cycle. We compared the effectiveness of animation of wall thickness encoded in color versus a static image of computed rate of wall thickness change in color. The location, extent and severity of regional wall akinesis or dyskinesis, as determined from these displays, can then be compared to the region of embolization as indicated by the distribution of altered LV wall perfusion.
Innovative LIDAR 3D Dynamic Measurement System to estimate fruit-tree leaf area.
Sanz-Cortiella, Ricardo; Llorens-Calveras, Jordi; Escolà, Alexandre; Arnó-Satorra, Jaume; Ribes-Dasi, Manel; Masip-Vilalta, Joan; Camp, Ferran; Gràcia-Aguilá, Felip; Solanelles-Batlle, Francesc; Planas-DeMartí, Santiago; Pallejà-Cabré, Tomàs; Palacin-Roca, Jordi; Gregorio-Lopez, Eduard; Del-Moral-Martínez, Ignacio; Rosell-Polo, Joan R
2011-01-01
In this work, a LIDAR-based 3D Dynamic Measurement System is presented and evaluated for the geometric characterization of tree crops. Using this measurement system, trees were scanned from two opposing sides to obtain two three-dimensional point clouds. After registration of the point clouds, a simple and easily obtainable parameter is the number of impacts received by the scanned vegetation. The work in this study is based on the hypothesis of the existence of a linear relationship between the number of impacts of the LIDAR sensor laser beam on the vegetation and the tree leaf area. Tests performed under laboratory conditions using an ornamental tree and, subsequently, in a pear tree orchard demonstrate the correct operation of the measurement system presented in this paper. The results from both the laboratory and field tests confirm the initial hypothesis and the 3D Dynamic Measurement System is validated in field operation. This opens the door to new lines of research centred on the geometric characterization of tree crops in the field of agriculture and, more specifically, in precision fruit growing.
Dynamic 3-D virtual fixtures for minimally invasive beating heart procedures.
Ren, Jing; Patel, Rajni V; McIsaac, Kenneth A; Guiraudon, Gerard; Peters, Terry M
2008-08-01
Two-dimensional or 3-D visual guidance is often used for minimally invasive cardiac surgery and diagnosis. This visual guidance suffers from several drawbacks such as limited field of view, loss of signal from time to time, and in some cases, difficulty of interpretation. These limitations become more evident in beating-heart procedures when the surgeon has to perform a surgical procedure in the presence of heart motion. In this paper, we propose dynamic 3-D virtual fixtures (DVFs) to augment the visual guidance system with haptic feedback, to provide the surgeon with more helpful guidance by constraining the surgeon's hand motions thereby protecting sensitive structures. DVFs can be generated from preoperative dynamic magnetic resonance (MR) or computed tomograph (CT) images and then mapped to the patient during surgery. We have validated the feasibility of the proposed method on several simulated surgical tasks using a volunteer's cardiac image dataset. Validation results show that the integration of visual and haptic guidance can permit a user to perform surgical tasks more easily and with reduced error rate. We believe this is the first work presented in the field of virtual fixtures that explicitly considers heart motion.
Innovative LIDAR 3D Dynamic Measurement System to estimate fruit-tree leaf area.
Sanz-Cortiella, Ricardo; Llorens-Calveras, Jordi; Escolà, Alexandre; Arnó-Satorra, Jaume; Ribes-Dasi, Manel; Masip-Vilalta, Joan; Camp, Ferran; Gràcia-Aguilá, Felip; Solanelles-Batlle, Francesc; Planas-DeMartí, Santiago; Pallejà-Cabré, Tomàs; Palacin-Roca, Jordi; Gregorio-Lopez, Eduard; Del-Moral-Martínez, Ignacio; Rosell-Polo, Joan R
2011-01-01
In this work, a LIDAR-based 3D Dynamic Measurement System is presented and evaluated for the geometric characterization of tree crops. Using this measurement system, trees were scanned from two opposing sides to obtain two three-dimensional point clouds. After registration of the point clouds, a simple and easily obtainable parameter is the number of impacts received by the scanned vegetation. The work in this study is based on the hypothesis of the existence of a linear relationship between the number of impacts of the LIDAR sensor laser beam on the vegetation and the tree leaf area. Tests performed under laboratory conditions using an ornamental tree and, subsequently, in a pear tree orchard demonstrate the correct operation of the measurement system presented in this paper. The results from both the laboratory and field tests confirm the initial hypothesis and the 3D Dynamic Measurement System is validated in field operation. This opens the door to new lines of research centred on the geometric characterization of tree crops in the field of agriculture and, more specifically, in precision fruit growing. PMID:22163926
Geophysical Fluid Dynamics Outreach Films
NASA Astrophysics Data System (ADS)
Aurnou, J. M.; Schwarz, J. W.; Noguez, G.
2012-12-01
Here we will present high definition films of laboratory experiments demonstrating basic fluid motions similar to those occurring in atmospheres and oceans. In these experiments, we use water to simulate the fluid dynamics of both the liquid (oceans) and gaseous (atmospheric) envelopes. To simulate the spinning of the earth, we carry out the experiments on a rotating table. For each experiment, we begin by looking at our system first without the effects of rotation. Then, we include rotation to see how the behavior of the fluid changes due to the Coriolis accelerations. Our hope is that by viewing these experiments one will develop a sense for how fluids behave both in rotating and non-rotating systems. By noting the differences between the experiments, it should then be possible to establish a basis to think about large-scale fluid motions that exist in Earth's oceans and atmospheres as well as on planets other than Earth.Plan view image of vortices in a rotating tank of fluid. Movies of such flows make accessible the often difficult to comprehend fluid dynamical processes that occur in planetary atmospheres and oceans.
Ito, Takashi; Pilat, Marcin L; Suzuki, Reiji; Arita, Takaya
2016-01-01
Recent studies have reported that population dynamics and evolutionary dynamics, occurring at different time scales, can be affected by each other. Our purpose is to explore the interaction between population and evolutionary dynamics using an artificial life approach based on a 3D physically simulated environment in the context of predator-prey and morphology-behavior coevolution. The morphologies and behaviors of virtual prey creatures are evolved using a genetic algorithm based on the predation interactions between predators and prey. Both population sizes are also changed, depending on the fitness. We observe two types of cyclic behaviors, corresponding to short-term and long-term dynamics. The former can be interpreted as a simple population dynamics of Lotka-Volterra type. It is shown that the latter cycle is based on the interaction between the changes in the prey strategy against predators and the long-term change in both population sizes, resulting partly from a tradeoff between their defensive success and the cost of defense.
3D microscale laser dynamic forming: Multiscale modeling and experimental validation
Gao Huang; Cheng, Gary J.
2011-05-15
Microscale laser dynamic forming ({mu}LDF) shows great potential in fabricating robust and high-aspect-ratio metallic microcomponents. Experiments revealed that strain rate and sample size play important roles in determining the dynamic plasticity and final results of {mu}LDF. To further understand these effects, a multiscale modeling methodology is adopted to characterize the microscale dynamic plasticity considering the evolutions of nano-to-submicron dislocations avalanches under shock loading. In this methodology, 3D discrete dislocation dynamics simulations are implemented to derive the yield strength and the initial strain hardening dependence on size and strain rate. It is observed that there exist three dynamic stages during deformation process. The initial strain hardening rate in Stage II increases with strain rate. The mechanical threshold stress model, intrinsically equipped with strain-rate-dependent flow stress and initial hardening, is chosen and modified to incorporate size effect quantitatively. This scale-dependent model, implemented in abaqus/explicit, provides deformation depths and thickness variations in good agreement with experimental results in {mu}LDF.
Ito, Takashi; Pilat, Marcin L; Suzuki, Reiji; Arita, Takaya
2016-01-01
Recent studies have reported that population dynamics and evolutionary dynamics, occurring at different time scales, can be affected by each other. Our purpose is to explore the interaction between population and evolutionary dynamics using an artificial life approach based on a 3D physically simulated environment in the context of predator-prey and morphology-behavior coevolution. The morphologies and behaviors of virtual prey creatures are evolved using a genetic algorithm based on the predation interactions between predators and prey. Both population sizes are also changed, depending on the fitness. We observe two types of cyclic behaviors, corresponding to short-term and long-term dynamics. The former can be interpreted as a simple population dynamics of Lotka-Volterra type. It is shown that the latter cycle is based on the interaction between the changes in the prey strategy against predators and the long-term change in both population sizes, resulting partly from a tradeoff between their defensive success and the cost of defense. PMID:26934093
NASA Technical Reports Server (NTRS)
Walatka, Pamela P.; Buning, Pieter G.; Pierce, Larry; Elson, Patricia A.
1990-01-01
PLOT3D is a computer graphics program designed to visualize the grids and solutions of computational fluid dynamics. Seventy-four functions are available. Versions are available for many systems. PLOT3D can handle multiple grids with a million or more grid points, and can produce varieties of model renderings, such as wireframe or flat shaded. Output from PLOT3D can be used in animation programs. The first part of this manual is a tutorial that takes the reader, keystroke by keystroke, through a PLOT3D session. The second part of the manual contains reference chapters, including the helpfile, data file formats, advice on changing PLOT3D, and sample command files.
Turbulent saturation and transport in global 3D two-fluid simulations of the tokamak edge
NASA Astrophysics Data System (ADS)
Rogers, Barrett; Ricci, Paolo
2012-03-01
Based on nonlinear, global, three-dimensional two-fluid simulations, we explore the physics of turbulent saturation and transport in the tokamak scape-off layer and other magnetic geometries. We find that the global simulations can produce larger relative fluctuation amplitudes and more Bohm-like (versus Gyro-Bohm-like) transport scalings than those of non-global (flux-tube) simulations. In both the global and local simulations, small-scale primary instabilities such as driftwaves or resistive ballooning modes produce radial streamers, which grow until they are broken up by secondary modes such as the Kelvin-Helmholz instability or related modes. In a local simulation with fixed, radially constant equilibrium gradients and periodic boundaries, for example, the radial elongation of these primary-mode streamers is, in principle, unlimited. In the global simulations, however, the radial extent of the primaries is truncated by the nonlocal radial variations of the equilibrium profile gradients, typically to the geometric mean of the equilibrium profile scale-length and poloidal scale-length of the primary modes. This radial truncation can have a strongly stabilizing effect on the KH mode, leading to larger primary-mode fluctuation levels and non-Gyro-Bohm transport scaling.
NASA Astrophysics Data System (ADS)
Tian, Fang-Bao; Dai, Hu; Luo, Haoxiang; Doyle, James F.; Rousseau, Bernard
2014-02-01
Three-dimensional fluid-structure interaction (FSI) involving large deformations of flexible bodies is common in biological systems, but accurate and efficient numerical approaches for modeling such systems are still scarce. In this work, we report a successful case of combining an existing immersed-boundary flow solver with a nonlinear finite-element solid-mechanics solver specifically for three-dimensional FSI simulations. This method represents a significant enhancement from the similar methods that are previously available. Based on the Cartesian grid, the viscous incompressible flow solver can handle boundaries of large displacements with simple mesh generation. The solid-mechanics solver has separate subroutines for analyzing general three-dimensional bodies and thin-walled structures composed of frames, membranes, and plates. Both geometric nonlinearity associated with large displacements and material nonlinearity associated with large strains are incorporated in the solver. The FSI is achieved through a strong coupling and partitioned approach. We perform several validation cases, and the results may be used to expand the currently limited database of FSI benchmark study. Finally, we demonstrate the versatility of the present method by applying it to the aerodynamics of elastic wings of insects and the flow-induced vocal fold vibration.
3D Dynamics of the Near-Surface Layer of the Ocean in the Presence of Freshwater Influx
NASA Astrophysics Data System (ADS)
Dean, C.; Soloviev, A.
2015-12-01
Freshwater inflow due to convective rains or river runoff produces lenses of freshened water in the near surface layer of the ocean. These lenses are localized in space and typically involve both salinity and temperature anomalies. Due to significant density anomalies, strong pressure gradients develop, which result in lateral spreading of freshwater lenses in a form resembling gravity currents. Gravity currents inherently involve three-dimensional dynamics. The gravity current head can include the Kelvin-Helmholtz billows with vertical density inversions. In this work, we have conducted a series of numerical experiments using computational fluid dynamics tools. These numerical simulations were designed to elucidate the relationship between vertical mixing and horizontal advection of salinity under various environmental conditions and potential impact on the pollution transport including oil spills. The near-surface data from the field experiments in the Gulf of Mexico during the SCOPE experiment were available for validation of numerical simulations. In particular, we observed a freshwater layer within a few-meter depth range and, in some cases, a density inversion at the edge of the freshwater lens, which is consistent with the results of numerical simulations. In conclusion, we discuss applicability of these results to the interpretation of Aquarius and SMOS sea surface salinity satellite measurements. The results of this study indicate that 3D dynamics of the near-surface layer of the ocean are essential in the presence of freshwater inflow.
Incompressible Viscous Fluid Dynamics
1992-02-13
NACHOS2 is a finite element program designed for the analysis of two-dimensional, incompressible viscous fluid flow problems. The basic flows considered may be isothermal, nonisothermal, or may involve other physical processes, such as mass transport. Both steady and transient flows may be analyzed. The class of problems treated are those described by the two-dimensional (plane or axisymmetric) incompressible form of the Navier-Stokes equations. An energy transport equation is included in the formulation for problems inmore » which heat transfer effects are important. Two auxiliary transport equations can be added to describe other physical processes,e.g. mass transfer, chemical reactions. Among the specific types of flow problems treated are: isothermal flow; forced, free, or mixed convection; conjugate heat transfer; flow in saturated porous media with or without heat transfer; and inelastic, non-Newtonian flows with or without heat transfer. Other problem classes are possible depending on the specific definitions applied to the auxiliary transport equations.« less
NASA Astrophysics Data System (ADS)
Inogamov, Nail A.; Zhakhovsky, Vasily V.
2016-02-01
There are many important applications in which the ultrashort diffraction-limited and therefore tightly focused laser pulses irradiates metal films mounted on dielectric substrate. Here we present the detailed picture of laser peeling and 3D structure formation of the thin (relative to a depth of a heat affected zone in the bulk targets) gold films on glass substrate. The underlying physics of such diffraction-limited laser peeling was not well understood previously. Our approach is based on a physical model which takes into consideration the new calculations of the two-temperature (2T) equation of state (2T EoS) and the two-temperature transport coefficients together with the coupling parameter between electron and ion subsystems. The usage of the 2T EoS and the kinetic coefficients is required because absorption of an ultrashort pulse with duration of 10-1000 fs excites electron subsystem of metal and transfers substance into the 2T state with hot electrons (typical electron temperatures 1-3 eV) and much colder ions. It is shown that formation of submicrometer-sized 3D structures is a result of the electron-ion energy transfer, melting, and delamination of film from substrate under combined action of electron and ion pressures, capillary deceleration of the delaminated liquid metal or semiconductor, and ultrafast freezing of molten material. We found that the freezing is going in non-equilibrium regime with strongly overcooled liquid phase. In this case the Stefan approximation is non-applicable because the solidification front speed is limited by the diffusion rate of atoms in the molten material. To solve the problem we have developed the 2T Lagrangian code including all this reach physics in. We also used the high-performance combined Monte- Carlo and molecular dynamics code for simulation of surface 3D nanostructuring at later times after completion of electron-ion relaxation.
Artificial Heart Fluid Dynamics.
NASA Astrophysics Data System (ADS)
Mussivand, Tofigh Varcaneh
Flow characteristics within pneumatic, pulsatile, and pusher plate prosthetic hearts were studied. The blood pumps evaluated were duplicates of pumps used for in vivo calf and for clinical implantation at the Cleveland Clinic Foundation. Human dura mater bioprosthetic, caged disk, and Bjork-Shiley tilting disk valves were employed in the pumps. Dual camera video tape and synchronized still photography were used to study flow patterns. Diffused light and a planar laser source provided illumination. The laser light was fanned into a plane with a thickness of 0.2 mm to 10 mm. Magnesium oxide and Amberlite particles were used as tracers. Aqueous-glycerol, aqueous-sucrose solutions and mineral oil were used as blood analog fluids. Inflow, outflow, drive, and afterload pressures, diaphragm motion, cardiac output, and heart rate were measured and recorded. An electrical circuit was developed to synchronize pump diaphragm motion with captured images of flow trajectories. After digitizing the trajectories, velocities, global and local turbulence, and shear stresses were obtained. Disturbed and recirculating zones were identified. Qualitative and quantitative analyses were performed using data obtained from the digitization of flow trajectories. Simultaneous turbulence and stasis were observed during most phases of the cardiac cycles in all the pumps tested. A maximum Reynold's shear stress of 2889 dynes/cm ^2 occurred at 120 beats per minute (bpm). The peak velocity was 146 cm/sec during systole. The identified regions of recirculation, low velocity and disturbed flow were shown to correlate with thrombosed areas of explanted blood pumps. The maximum calculated turbulence intensity was 106 cm/sec which occurred at 120 bpm during systole.
Static and dynamic crystalline lens accommodation evaluated using quantitative 3-D OCT
Gambra, Enrique; Ortiz, Sergio; Perez-Merino, Pablo; Gora, Michalina; Wojtkowski, Maciej; Marcos, Susana
2013-01-01
Custom high-resolution high-speed anterior segment spectral domain Optical Coherence Tomography (OCT) provided with automatic quantification and distortion correction algorithms was used to characterize three-dimensionally (3-D) the human crystalline lens in vivo in four subjects, for accommodative demands between 0 to 6 D in 1 D steps. Anterior and posterior lens radii of curvature decreased with accommodative demand at rates of 0.73 and 0.20 mm/D, resulting in an increase of the estimated optical power of the eye of 0.62 D per diopter of accommodative demand. Dynamic fluctuations in crystalline lens radii of curvature, anterior chamber depth and lens thickness were also estimated from dynamic 2-D OCT images (14 Hz), acquired during 5-s of steady fixation, for different accommodative demands. Estimates of the eye power from dynamical geometrical measurements revealed an increase of the fluctuations of the accommodative response from 0.07 D to 0.47 D between 0 and 6 D (0.044 D per D of accommodative demand). A sensitivity analysis showed that the fluctuations of accommodation were driven by dynamic changes in the lens surfaces, particularly in the posterior lens surface. PMID:24049680
Observing molecular dynamics with time-resolved 3D momentum imaging
NASA Astrophysics Data System (ADS)
Sturm, F. P.; Wright, T.; Bocharova, I.; Ray, D.; Shivaram, N.; Cryan, J.; Belkacem, A.; Weber, T.; Dörner, R.
2014-05-01
Photo-excitation and ionization trigger rich dynamics in molecular systems which play a key role in many important processes in nature such as vision, photosynthesis or photoprotection. Observing those reactions in real-time without significantly disturbing the molecules by a strong electric field has been a great challenge. Recent experiments using Time-of-Flight and Velocity Map Imaging techniques have revealed important information on the dynamics of small molecular systems upon photo-excitation. We have developed an apparatus for time-resolved momentum imaging of electrons and ions in all three spatial dimensions that employs two-color femtosecond laser pulses in the vacuum and extreme ultraviolet (VUV, XUV) for probing molecular dynamics. Our COLTRIMS style reaction microscope can measure electrons and ions in coincidence and reconstruct the momenta of the reaction fragments in 3D. We use a high power 800 nm laser in a loose focusing geometry gas cell to efficinetly drive High Harmonic Generation. The resulting photon flux is sufficient to perform 2-photon pump-probe experiments using VUV and XUV pulses for both pump and probe. With this setup we investigate non-Born-Oppenheimer dynamics in small molecules such as C2H4 and CO2 on a femtosecond time scale. Supported by Chemical Sciences, Geosciences and Biosciences division of BES/DOE.
Defragmented image based autostereoscopic 3D displays with dynamic eye tracking
NASA Astrophysics Data System (ADS)
Kim, Sung-Kyu; Yoon, Ki-Hyuk; Yoon, Seon Kyu; Ju, Heongkyu
2015-12-01
We studied defragmented image based autostereoscopic 3D displays with dynamic eye tracking. Specifically, we examined the impact of parallax barrier (PB) angular orientation on their image quality. The 3D display system required fine adjustment of PB angular orientation with respect to a display panel. This was critical for both image color balancing and minimizing image resolution mismatch between horizontal and vertical directions. For evaluating uniformity of image brightness, we applied optical ray tracing simulations. The simulations took effects of PB orientation misalignment into account. The simulation results were then compared with recorded experimental data. Our optimal simulated system produced significantly enhanced image uniformity at around sweet spots in viewing zones. However this was contradicted by real experimental results. We offer quantitative treatment of illuminance uniformity of view images to estimate misalignment of PB orientation, which could account for brightness non-uniformity observed experimentally. Our study also shows that slight imperfection in the adjustment of PB orientation due to practical restrictions of adjustment accuracy can induce substantial non-uniformity of view images' brightness. We find that image brightness non-uniformity critically depends on misalignment of PB angular orientation, for example, as slight as ≤ 0.01 ° in our system. This reveals that reducing misalignment of PB angular orientation from the order of 10-2 to 10-3 degrees can greatly improve the brightness uniformity.
McCullough, D P; Gudla, P R; Harris, B S; Collins, J A; Meaburn, K J; Nakaya, M A; Yamaguchi, T P; Misteli, T; Lockett, S J
2008-05-01
Communications between cells in large part drive tissue development and function, as well as disease-related processes such as tumorigenesis. Understanding the mechanistic bases of these processes necessitates quantifying specific molecules in adjacent cells or cell nuclei of intact tissue. However, a major restriction on such analyses is the lack of an efficient method that correctly segments each object (cell or nucleus) from 3-D images of an intact tissue specimen. We report a highly reliable and accurate semi-automatic algorithmic method for segmenting fluorescence-labeled cells or nuclei from 3-D tissue images. Segmentation begins with semi-automatic, 2-D object delineation in a user-selected plane, using dynamic programming (DP) to locate the border with an accumulated intensity per unit length greater that any other possible border around the same object. Then the two surfaces of the object in planes above and below the selected plane are found using an algorithm that combines DP and combinatorial searching. Following segmentation, any perceived errors can be interactively corrected. Segmentation accuracy is not significantly affected by intermittent labeling of object surfaces, diffuse surfaces, or spurious signals away from surfaces. The unique strength of the segmentation method was demonstrated on a variety of biological tissue samples where all cells, including irregularly shaped cells, were accurately segmented based on visual inspection.
Description of patellar movement by 3D parameters obtained from dynamic CT acquisition
NASA Astrophysics Data System (ADS)
de Sá Rebelo, Marina; Moreno, Ramon Alfredo; Gobbi, Riccardo Gomes; Camanho, Gilberto Luis; de Ávila, Luiz Francisco Rodrigues; Demange, Marco Kawamura; Pecora, Jose Ricardo; Gutierrez, Marco Antonio
2014-03-01
The patellofemoral joint is critical in the biomechanics of the knee. The patellofemoral instability is one condition that generates pain, functional impairment and often requires surgery as part of orthopedic treatment. The analysis of the patellofemoral dynamics has been performed by several medical image modalities. The clinical parameters assessed are mainly based on 2D measurements, such as the patellar tilt angle and the lateral shift among others. Besides, the acquisition protocols are mostly performed with the leg laid static at fixed angles. The use of helical multi slice CT scanner can allow the capture and display of the joint's movement performed actively by the patient. However, the orthopedic applications of this scanner have not yet been standardized or widespread. In this work we present a method to evaluate the biomechanics of the patellofemoral joint during active contraction using multi slice CT images. This approach can greatly improve the analysis of patellar instability by displaying the physiology during muscle contraction. The movement was evaluated by computing its 3D displacements and rotations from different knee angles. The first processing step registered the images in both angles based on the femuŕs position. The transformation matrix of the patella from the images was then calculated, which provided the rotations and translations performed by the patella from its position in the first image to its position in the second image. Analysis of these parameters for all frames provided real 3D information about the patellar displacement.
Brownian nanoimaging of interface dynamics and ligand-receptor binding at cell surfaces in 3-D.
Kuznetsov, Igor R; Evans, Evan A
2013-04-01
We describe a method for nanoimaging interfacial dynamics and ligand-receptor binding at surfaces of live cells in 3-D. The imaging probe is a 1-μm diameter glass bead confined by a soft laser trap to create a "cloud" of fluctuating states. Using a facile on-line method of video image analysis, the probe displacements are reported at ~10 ms intervals with bare precisions (±SD) of 4-6 nm along the optical axis (elevation) and 2 nm in the transverse directions. We demonstrate how the Brownian distributions are analyzed to characterize the free energy potential of each small probe in 3-D taking into account the blur effect of its motions during CCD image capture. Then, using the approach to image interactions of a labeled probe with lamellae of leukocytic cells spreading on cover-glass substrates, we show that deformations of the soft distribution in probe elevations provide both a sensitive long-range sensor for defining the steric topography of a cell lamella and a fast telemetry for reporting rare events of probe binding with its surface receptors. Invoking established principles of Brownian physics and statistical thermodynamics, we describe an off-line method of super resolution that improves precision of probe separations from a non-reactive steric boundary to ~1 nm.
Mutual information as a measure of image quality for 3D dynamic lung imaging with EIT
Crabb, M G; Davidson, J L; Little, R; Wright, P; Morgan, A R; Miller, C A; Naish, J H; Parker, G J M; Kikinis, R; McCann, H; Lionheart, W R B
2014-01-01
We report on a pilot study of dynamic lung electrical impedance tomography (EIT) at the University of Manchester. Low-noise EIT data at 100 frames per second (fps) were obtained from healthy male subjects during controlled breathing, followed by magnetic resonance imaging (MRI) subsequently used for spatial validation of the EIT reconstruction. The torso surface in the MR image and electrode positions obtained using MRI fiducial markers informed the construction of a 3D finite element model extruded along the caudal-distal axis of the subject. Small changes in the boundary that occur during respiration were accounted for by incorporating the sensitivity with respect to boundary shape into a robust temporal difference reconstruction algorithm. EIT and MRI images were co-registered using the open source medical imaging software, 3D Slicer. A quantitative comparison of quality of different EIT reconstructions was achieved through calculation of the mutual information with a lung-segmented MR image. EIT reconstructions using a linear shape correction algorithm reduced boundary image artefacts, yielding better contrast of the lungs, and had 10% greater mutual information compared with a standard linear EIT reconstruction. PMID:24710978
Computational Fluid Dynamics For Helicopters
NASA Technical Reports Server (NTRS)
Caradonna, F. X.; Mccroskey, W. J.
1990-01-01
Powerful computer codes undergoing development. Report reviews development of computational fluid dynamics (CFD) for prediction of airflow around rotary wings of helicopters. Reviews progress in following endeavors: Prediction and verification of flows under various operating conditions; calculation of interactions between rotor blades and vortexes; analysis of viscous, transonic flows about airfoils; and study of formation of vortexes at tips of rotors.
NASA Astrophysics Data System (ADS)
Hu, Shengsun; Guo, Chaobo; Wang, Dongpo; Wang, Zhijiang
2016-09-01
The nonuniform distributions of the residual stress were simulated by a 3D finite element model to analyze the elastic-plastic dynamic ultrasonic impact treatment (UIT) process of multiple impacts on the 2024 aluminum alloy. The evolution of the stress during the impact process was discussed. The successive impacts during the UIT process improve the uniformity of the plastic deformation and decrease the maximum compressive residual stress beneath the former impact indentations. The influences of different controlled parameters, including the initial impact velocity, pin diameter, pin tip, device moving, and offset distances, on the residual stress distributions were analyzed. The influences of the controlled parameters on the residual stress distributions are apparent in the offset direction due to the different surface coverage in different directions. The influences can be used to understand the UIT process and to obtain the desired residual stress by optimizing the controlled parameters.
Dynamic Implicit 3D Adaptive Mesh Refinement for Non-Equilibrium Radiation Diffusion
Philip, Bobby; Wang, Zhen; Berrill, Mark A; Rodriguez Rodriguez, Manuel; Pernice, Michael
2014-01-01
The time dependent non-equilibrium radiation diffusion equations are important for solving the transport of energy through radiation in optically thick regimes and find applications in several fields including astrophysics and inertial confinement fusion. The associated initial boundary value problems that are encountered exhibit a wide range of scales in space and time and are extremely challenging to solve. To efficiently and accurately simulate these systems we describe our research on combining techniques that will also find use more broadly for long term time integration of nonlinear multiphysics systems: implicit time integration for efficient long term time integration of stiff multiphysics systems, local control theory based step size control to minimize the required global number of time steps while controlling accuracy, dynamic 3D adaptive mesh refinement (AMR) to minimize memory and computational costs, Jacobian Free Newton Krylov methods on AMR grids for efficient nonlinear solution, and optimal multilevel preconditioner components that provide level independent linear solver convergence.
NASA Astrophysics Data System (ADS)
Bu, Shuhui; Shiina, Tsuyoshi; Yamakawa, Makoto; Takizawa, Hotaka
Accurate assessment of local myocardial contraction is important for diagnosis of ischemic heart disease, because decreases of myocardial motion often appear in the early stages of the disease. Three-dimensional (3-D) assessment of the stiffness distribution is required for accurate diagnosis of ischemic heart disease. Since myocardium motion occurs radially within the left ventricle wall and the ultrasound beam propagates axially, conventional approaches, such as tissue Doppler imaging and strain-rate imaging techniques, cannot provide us with enough quantitative information about local myocardial contraction. In order to resolve this problem, we propose a novel myocardial contraction imaging system which utilizes the weighted phase gradient method, the extended combined autocorrelation method, and the dynamic grid interpolation (DGI) method. From the simulation results, we conclude that the strain image's accuracy and contrast have been improved by the proposed method.
3D Plasma Clusters: Analysis of dynamical evolution and individual particle interaction
Antonova, T.; Thomas, H. M.; Morfill, G. E.; Annaratone, B. M.
2008-09-07
3D plasma clusters (up to 100 particles) have been built inside small (32 mm{sup 3}) plasma volume in gravity. It has been estimated that the external confinement has a negligible influence on the processes inside the clusters. At such conditions the analysis of dynamical evolution and individual particle interactions have shown that the binary interaction among particles in addition to the repelling Coulomb force exhibits also an attractive part. The tendency of the systems to approach the state with minimum energy by rearranging particles inside has been detected. The measured 63 particles' cluster vibrations are in close agreement with vibrations of a drop with surface tension. This indicates that even a 63 particle cluster already exhibits properties normally associated with the cooperative regime.
3D Plasma Clusters: Analysis of dynamical evolution and individual particle interaction
NASA Astrophysics Data System (ADS)
Antonova, T.; Annaratone, B. M.; Thomas, H. M.; Morfill, G. E.
2008-09-01
3D plasma clusters (up to 100 particles) have been built inside small (32 mm3) plasma volume in gravity. It has been estimated that the external confinement has a negligible influence on the processes inside the clusters. At such conditions the analysis of dynamical evolution and individual particle interactions have shown that the binary interaction among particles in addition to the repelling Coulomb force exhibits also an attractive part. The tendency of the systems to approach the state with minimum energy by rearranging particles inside has been detected. The measured 63 particles' cluster vibrations are in close agreement with vibrations of a drop with surface tension. This indicates that even a 63 particle cluster already exhibits properties normally associated with the cooperative regime.
Self-Consistent 3D Modeling of Electron Cloud Dynamics and Beam Response
Furman, Miguel; Furman, M.A.; Celata, C.M.; Kireeff-Covo, M.; Sonnad, K.G.; Vay, J.-L.; Venturini, M.; Cohen, R.; Friedman, A.; Grote, D.; Molvik, A.; Stoltz, P.
2007-04-02
We present recent advances in the modeling of beam electron-cloud dynamics, including surface effects such as secondary electron emission, gas desorption, etc, and volumetric effects such as ionization of residual gas and charge-exchange reactions. Simulations for the HCX facility with the code WARP/POSINST will be described and their validity demonstrated by benchmarks against measurements. The code models a wide range of physical processes and uses a number of novel techniques, including a large-timestep electron mover that smoothly interpolates between direct orbit calculation and guiding-center drift equations, and a new computational technique, based on a Lorentz transformation to a moving frame, that allows the cost of a fully 3D simulation to be reduced to that of a quasi-static approximation.
NASA Astrophysics Data System (ADS)
Bardsley, C.; Sewell, S.; Cumming, W. B.; Minnick, M.; Rowland, J. V.; O'Brien, J.; Price, L.
2012-12-01
Identifying permeable zones is essential for economically viable exploration and development of conventional geothermal reservoirs with naturally high permeability. Except very close to boreholes, the resolution of geological and geophysical tools is at a much larger scale than the centimetre aperture of most geothermal fluid pathways important to production. A case study from the >250°C Rotokawa Geothermal Field, currently producing 175 MWe within the Taupo Volcanic Zone in New Zealand, illustrates how a 3D visualization of a subset of available data that are conceptually relevant at the scales of interest has enhanced the understanding of fluid flow within this system. Geoscience data sets including subsurface formation geometry and permeable zones in wells; the natural state temperature pattern deduced from wells and MT resistivity; microearthquakes (MEQ) induced by injection, and surface geology have been integrated with engineering data including production pressure responses and injection rates to constrain the location and general hydraulic properties of one of the most influential faults in the field. Stratigraphic offsets of >500 m, recorded in core and cuttings from wells drilled on either side of the field, confirm the presence of this fault, initially suspected based on a surface lineation of eight young (<22 ka) hydrothermal eruption craters. The 3D visualization of the MEQ occurrence pattern in space and time helps constrain the mechanism of the MEQs themselves and, importantly, the confinement of most of the MEQs to the eastern side of the fault closest to the injection wells. Hosted within the Mesozoic meta-sedimentary basement formation, this has provided an important conceptual constraint that explains the lack of injection fluid on the western side of this fault. Further to this, if this fault is acting as a barrier at the Mesozoic meta-sedimentary level today, this could imply a switch in the behaviour of this structure as it is inferred, based
3D Reconstruction of Human Laryngeal Dynamics Based on Endoscopic High-Speed Recordings.
Semmler, Marion; Kniesburges, Stefan; Birk, Veronika; Ziethe, Anke; Patel, Rita; Dollinger, Michael
2016-07-01
Standard laryngoscopic imaging techniques provide only limited two-dimensional insights into the vocal fold vibrations not taking the vertical component into account. However, previous experiments have shown a significant vertical component in the vibration of the vocal folds. We present a 3D reconstruction of the entire superior vocal fold surface from 2D high-speed videoendoscopy via stereo triangulation. In a typical camera-laser set-up the structured laser light pattern is projected on the vocal folds and captured at 4000 fps. The measuring device is suitable for in vivo application since the external dimensions of the miniaturized set-up barely exceed the size of a standard rigid laryngoscope. We provide a conservative estimate on the resulting resolution based on the hardware components and point out the possibilities and limitations of the miniaturized camera-laser set-up. In addition to the 3D vocal fold surface, we extended previous approaches with a G2-continuous model of the vocal fold edge. The clinical applicability was successfully established by the reconstruction of visual data acquired from 2D in vivo high-speed recordings of a female and a male subject. We present extracted dynamic parameters like maximum amplitude and velocity in the vertical direction. The additional vertical component reveals deeper insights into the vibratory dynamics of the vocal folds by means of a non-invasive method. The successful miniaturization allows for in vivo application giving access to the most realistic model available and hence enables a comprehensive understanding of the human phonation process. PMID:26829782
He, Wei; Anderson, Roger N.
1998-01-01
A method is disclosed for inverting 3-D seismic reflection data obtained from seismic surveys to derive impedance models for a subsurface region, and for inversion of multiple 3-D seismic surveys (i.e., 4-D seismic surveys) of the same subsurface volume, separated in time to allow for dynamic fluid migration, such that small scale structure and regions of fluid and dynamic fluid flow within the subsurface volume being studied can be identified. The method allows for the mapping and quantification of available hydrocarbons within a reservoir and is thus useful for hydrocarbon prospecting and reservoir management. An iterative seismic inversion scheme constrained by actual well log data which uses a time/depth dependent seismic source function is employed to derive impedance models from 3-D and 4-D seismic datasets. The impedance values can be region grown to better isolate the low impedance hydrocarbon bearing regions. Impedance data derived from multiple 3-D seismic surveys of the same volume can be compared to identify regions of dynamic evolution and bypassed pay. Effective Oil Saturation or net oil thickness can also be derived from the impedance data and used for quantitative assessment of prospective drilling targets and reservoir management.
He, W.; Anderson, R.N.
1998-08-25
A method is disclosed for inverting 3-D seismic reflection data obtained from seismic surveys to derive impedance models for a subsurface region, and for inversion of multiple 3-D seismic surveys (i.e., 4-D seismic surveys) of the same subsurface volume, separated in time to allow for dynamic fluid migration, such that small scale structure and regions of fluid and dynamic fluid flow within the subsurface volume being studied can be identified. The method allows for the mapping and quantification of available hydrocarbons within a reservoir and is thus useful for hydrocarbon prospecting and reservoir management. An iterative seismic inversion scheme constrained by actual well log data which uses a time/depth dependent seismic source function is employed to derive impedance models from 3-D and 4-D seismic datasets. The impedance values can be region grown to better isolate the low impedance hydrocarbon bearing regions. Impedance data derived from multiple 3-D seismic surveys of the same volume can be compared to identify regions of dynamic evolution and bypassed pay. Effective Oil Saturation or net oil thickness can also be derived from the impedance data and used for quantitative assessment of prospective drilling targets and reservoir management. 20 figs.
Fluid dynamic bowtie attenuators
NASA Astrophysics Data System (ADS)
Szczykutowicz, Timothy P.; Hermus, James
2015-03-01
Fluence field modulated CT allows for improvements in image quality and dose reduction. To date, only 1-D modulators have been proposed, the extension to 2-D modulation is difficult with solid-metal attenuation-based modulators. This work proposes to use liquids and gas to attenuate the x-ray beam which can be arrayed allowing for 2-D fluence modulation. The thickness of liquid and the pressure for a given path length of gas were determined that provided the same attenuation as 30 cm of soft tissue at 80, 100, 120, and 140 kV. Gaseous Xenon and liquid Iodine, Zinc Chloride, and Cerium Chloride were studied. Additionally, we performed some proof-of-concept experiments in which (1) a single cell of liquid was connected to a reservoir which allowed the liquid thickness to be modulated and (2) a 96 cell array was constructed in which the liquid thickness in each cell was adjusted manually. Liquid thickness varied as a function of kV and chemical composition, with Zinc Chloride allowing for the smallest thickness; 1.8, 2.25, 3, and 3.6 cm compensated for 30 cm of soft tissue at 80, 100, 120, and 140 kV respectively. The 96 cell Iodine attenuator allowed for a reduction in both dynamic range to the detector and scatter to primary ratio. Successful modulation of a single cell was performed at 0, 90, and 130 degrees using a simple piston/actuator. The thickness of liquids and the Xenon gas pressure seem logistically implementable within the constraints of CBCT and diagnostic CT systems.
Transforming 2d Cadastral Data Into a Dynamic Smart 3d Model
NASA Astrophysics Data System (ADS)
Tsiliakou, E.; Labropoulos, T.; Dimopoulou, E.
2013-08-01
3D property registration has become an imperative need in order to optimally reflect all complex cases of the multilayer reality of property rights and restrictions, revealing their vertical component. This paper refers to the potentials and multiple applications of 3D cadastral systems and explores the current state-of-the art, especially the available software with which 3D visualization can be achieved. Within this context, the Hellenic Cadastre's current state is investigated, in particular its data modeling frame. Presenting the methodologies and specifications addressing the registration of 3D properties, the operating cadastral system's shortcomings and merits are pointed out. Nonetheless, current technological advances as well as the availability of sophisticated software packages (proprietary or open source) call for 3D modeling. In order to register and visualize the complex reality in 3D, Esri's CityEngine modeling software has been used, which is specialized in the generation of 3D urban environments, transforming 2D GIS Data into Smart 3D City Models. The application of the 3D model concerns the Campus of the National Technical University of Athens, in which a complex ownership status is established along with approved special zoning regulations. The 3D model was built using different parameters based on input data, derived from cadastral and urban planning datasets, as well as legal documents and architectural plans. The process resulted in a final 3D model, optimally describing the cadastral situation and built environment and proved to be a good practice example of 3D visualization.
3D Dynamics of Magnetopause Reconnection Using Hall-MHD Global Simulations
NASA Astrophysics Data System (ADS)
Maynard, K.; Germaschewski, K.; Raeder, J.; Bhattacharjee, A.
2011-12-01
Magnetic reconnection at Earth's magnetopause and in the magnetotail is of crucial importance for the dynamics of the global magnetosphere and space weather. Even though the plasma conditions in the magnetosphere are largely in the collisionless regime, most of the existing research using global computational models employ single-fluid magnetohydrodynamics (MHD) with artificial resistivity. Studies of reconnection in simplified, two-dimensional geometries have established that two-fluid and kinetic effects can dramatically alter dynamics and reconnection rates when compared with single-fluid models. These enhanced models also introduce particular signatures, for example a quadrupolar out-of-plane magnetic field component that has already been observed in space by satellite measurements. However, results from simplified geometries cannot be translated directly to the dynamics of three-dimensional magnetospheric reconnection. For instance, magnetic flux originating from the solar wind and arriving at the magnetopause can either reconnect or be advected around the magnetosphere. In this study, we use a new version of the OpenGGCM code that incorporates the Hall term in a Generalized Ohm's Law to study magnetopause reconnection under synthetic solar wind conditions and investigate how reconnection rates and dynamics of flux transfer events depend on the strength of the Hall term. The OpenGGCM, a global model of Earth's magnetosphere, has recently been ported to exploit modern computing architectures like the Cell processor and SIMD capabilities of conventional processors using an automatic code generator. These enhancements provide us with the performance needed to include the computationally expensive Hall physics.
Computational fluid dynamics uses in fluid dynamics/aerodynamics education
NASA Technical Reports Server (NTRS)
Holst, Terry L.
1994-01-01
The field of computational fluid dynamics (CFD) has advanced to the point where it can now be used for the purpose of fluid dynamics physics education. Because of the tremendous wealth of information available from numerical simulation, certain fundamental concepts can be efficiently communicated using an interactive graphical interrogation of the appropriate numerical simulation data base. In other situations, a large amount of aerodynamic information can be communicated to the student by interactive use of simple CFD tools on a workstation or even in a personal computer environment. The emphasis in this presentation is to discuss ideas for how this process might be implemented. Specific examples, taken from previous publications, will be used to highlight the presentation.
Dynamic 3D-visualization of merged geophysical and geological data sets from the Arctic
NASA Astrophysics Data System (ADS)
Jakobsson, M. E.
2002-12-01
Bringing together geophysical and geological data sets in a dynamic 3D-environment can greatly enhance our ability to comprehend earth processes. The relationship between, for example, seafloor topography and measured gravity anomalies can easily be visualized as well as the distribution of magnetic anomalies in oceanic crust and their varying offset due to seafloor spreading. In this presentation the gravity derived from ERS-1 satellite altimetry by Laxon and McAdoo (1994) and the magnetic compilation by Verhoef et al. (1996) of the Arctic Ocean is co-registered with the International Bathymetric Chart of the Arctic Ocean (IBCAO) bathymetry and brought into a dynamic 3D-environment for visualization and analysis. This exercise provides information of great value when we address the geologic origin of the Arctic Ocean physiographic provinces. Furthermore, since the ERS-1 gravity and IBCAO bathymetry are two entirely unrelated datasets the gravity may also be used for validating seafloor features seen in the IBCAO compilation that are based on sparse data. For instance, at the eastern most end of the Gakkel Ridge Axial Valley the IBCAO bathymetry is based on digitized contour information from a Russian bathymetric map published in 1999 by the Russian Federation's Head Department of Navigation and Oceanography (HDNO) with no available trackline sources. In the bathymetry, the Axial Valley is clearly seen to continue towards the continental slope of the Laptev Sea and this continuation is supported by the ERS-1 gravity. Another example of bringing together geological and geophysical data sets is from northern Russia, where huge ice lakes were dammed by the Early Weichselian ice sheet at about 90 000 years ago (Mangerud et al., 2001). The damming resulted from blocking the Russian north flowing rivers, supplying most of the fresh water to the Arctic Ocean, by the Ice Sheet margin. These proglacial lakes are reconstructed in our dynamic 3D-environment based on field
Visualization of unsteady computational fluid dynamics
NASA Technical Reports Server (NTRS)
Haimes, Robert
1994-01-01
A brief summary of the computer environment used for calculating three dimensional unsteady Computational Fluid Dynamic (CFD) results is presented. This environment requires a super computer as well as massively parallel processors (MPP's) and clusters of workstations acting as a single MPP (by concurrently working on the same task) provide the required computational bandwidth for CFD calculations of transient problems. The cluster of reduced instruction set computers (RISC) is a recent advent based on the low cost and high performance that workstation vendors provide. The cluster, with the proper software can act as a multiple instruction/multiple data (MIMD) machine. A new set of software tools is being designed specifically to address visualizing 3D unsteady CFD results in these environments. Three user's manuals for the parallel version of Visual3, pV3, revision 1.00 make up the bulk of this report.
Remote Visualization and Remote Collaboration On Computational Fluid Dynamics
NASA Technical Reports Server (NTRS)
Watson, Val; Lasinski, T. A. (Technical Monitor)
1995-01-01
A new technology has been developed for remote visualization that provides remote, 3D, high resolution, dynamic, interactive viewing of scientific data (such as fluid dynamics simulations or measurements). Based on this technology, some World Wide Web sites on the Internet are providing fluid dynamics data for educational or testing purposes. This technology is also being used for remote collaboration in joint university, industry, and NASA projects in computational fluid dynamics and wind tunnel testing. Previously, remote visualization of dynamic data was done using video format (transmitting pixel information) such as video conferencing or MPEG movies on the Internet. The concept for this new technology is to send the raw data (e.g., grids, vectors, and scalars) along with viewing scripts over the Internet and have the pixels generated by a visualization tool running on the viewer's local workstation. The visualization tool that is currently used is FAST (Flow Analysis Software Toolkit).
Visualization of Computational Fluid Dynamics
NASA Technical Reports Server (NTRS)
Gerald-Yamasaki, Michael; Hultquist, Jeff; Bryson, Steve; Kenwright, David; Lane, David; Walatka, Pamela; Clucas, Jean; Watson, Velvin; Lasinski, T. A. (Technical Monitor)
1995-01-01
Scientific visualization serves the dual purpose of exploration and exposition of the results of numerical simulations of fluid flow. Along with the basic visualization process which transforms source data into images, there are four additional components to a complete visualization system: Source Data Processing, User Interface and Control, Presentation, and Information Management. The requirements imposed by the desired mode of operation (i.e. real-time, interactive, or batch) and the source data have their effect on each of these visualization system components. The special requirements imposed by the wide variety and size of the source data provided by the numerical simulation of fluid flow presents an enormous challenge to the visualization system designer. We describe the visualization system components including specific visualization techniques and how the mode of operation and source data requirements effect the construction of computational fluid dynamics visualization systems.
A novel time dependent gamma evaluation function for dynamic 2D and 3D dose distributions
NASA Astrophysics Data System (ADS)
Podesta, Mark; CGG Persoon, Lucas; Verhaegen, Frank
2014-10-01
Modern external beam radiotherapy requires detailed verification and quality assurance so that confidence can be placed on both the delivery of a single treatment fraction and on the consistency of delivery throughout the treatment course. To verify dose distributions, a comparison between prediction and measurement must be made. Comparisons between two dose distributions are commonly performed using a Gamma evaluation which is a calculation of two quantities on a pixel by pixel basis; the dose difference, and the distance to agreement. By providing acceptance criteria (e.g. 3%, 3 mm), the function will find the most appropriate match within its two degrees of freedom. For complex dynamic treatments such as IMRT or VMAT it is important to verify the dose delivery in a time dependent manner and so a gamma evaluation that includes a degree of freedom in the time domain via a third parameter, time to agreement, is presented here. A C++ (mex) based gamma function was created that could be run on either CPU and GPU computing platforms that would allow a degree of freedom in the time domain. Simple test cases were created in both 2D and 3D comprising of simple geometrical shapes with well-defined boundaries varying over time. Changes of varying magnitude in either space or time were introduced and repeated gamma analyses were performed varying the criteria. A clinical VMAT case was also included, artificial air bubbles of varying size were introduced to a patient geometry, along with shifts of varying magnitude in treatment time. For all test cases where errors in distance, dose or time were introduced, the time dependent gamma evaluation could accurately highlight the errors. The time dependent gamma function presented here allows time to be included as a degree of freedom in gamma evaluations. The function allows for 2D and 3D data sets which are varying over time to be compared using appropriate criteria without penalising minor offsets of subsequent radiation
A novel time dependent gamma evaluation function for dynamic 2D and 3D dose distributions.
Podesta, Mark; Persoon, Lucas C G G; Verhaegen, Frank
2014-10-21
Modern external beam radiotherapy requires detailed verification and quality assurance so that confidence can be placed on both the delivery of a single treatment fraction and on the consistency of delivery throughout the treatment course. To verify dose distributions, a comparison between prediction and measurement must be made. Comparisons between two dose distributions are commonly performed using a Gamma evaluation which is a calculation of two quantities on a pixel by pixel basis; the dose difference, and the distance to agreement. By providing acceptance criteria (e.g. 3%, 3 mm), the function will find the most appropriate match within its two degrees of freedom. For complex dynamic treatments such as IMRT or VMAT it is important to verify the dose delivery in a time dependent manner and so a gamma evaluation that includes a degree of freedom in the time domain via a third parameter, time to agreement, is presented here. A C++ (mex) based gamma function was created that could be run on either CPU and GPU computing platforms that would allow a degree of freedom in the time domain. Simple test cases were created in both 2D and 3D comprising of simple geometrical shapes with well-defined boundaries varying over time. Changes of varying magnitude in either space or time were introduced and repeated gamma analyses were performed varying the criteria. A clinical VMAT case was also included, artificial air bubbles of varying size were introduced to a patient geometry, along with shifts of varying magnitude in treatment time. For all test cases where errors in distance, dose or time were introduced, the time dependent gamma evaluation could accurately highlight the errors.The time dependent gamma function presented here allows time to be included as a degree of freedom in gamma evaluations. The function allows for 2D and 3D data sets which are varying over time to be compared using appropriate criteria without penalising minor offsets of subsequent radiation fields
A Real-time, 3D Musculoskeletal Model for Dynamic Simulation of Arm Movements
Chadwick, Edward K.; Blana, Dimitra; van den Bogert, Antonie J.; Kirsch, Robert F.
2010-01-01
Neuroprostheses can be used to restore movement of the upper limb in individuals with high-level spinal cord injury. Development and evaluation of command and control schemes for such devices typically requires real-time, “patient-in-the-loop” experimentation. A real-time, three-dimensional, musculoskeletal model of the upper limb has been developed for use in a simulation environment to allow such testing to be carried out non-invasively. The model provides real-time feedback of human arm dynamics that can be displayed to the user in a virtual reality environment. The model has a three degree-of-freedom gleno-humeral joint as well as elbow flexion/extension and pronation/supination, and contains 22 muscles of the shoulder and elbow divided into multiple elements. The model is able to run in real time on modest desktop hardware and demonstrates that a large-scale, 3D model can be made to run in real time. This is a prerequisite for a real-time, whole arm model that will form part of a dynamic arm simulator for use in the development, testing and user training of neural prosthesis systems. PMID:19272926
Analysis of Wnt signalling dynamics during colon crypt development in 3D culture
Tan, Chin Wee; Hirokawa, Yumiko; Burgess, Antony W.
2015-01-01
Many systems biology studies lack context-relevant data and as a consequence the predictive capabilities can be limited in developing targeted cancer therapeutics. Production of colon crypt in vitro is ideal for studying colon systems biology. This report presents the first production of, to our knowledge, physiologically-shaped, functional colon crypts in vitro (i.e. single crypts with cells expressing Mucin 2 and Chromogranin A). Time-lapsed monitoring of crypt formation revealed an increased frequency of single-crypt formation in the absence of noggin. Using quantitative 3D immunofluorescence of β-catenin and E-cadherin, spatial-temporal dynamics of these proteins in normal colon crypt cells stimulated with Wnt3A or inhibited by cycloheximide has been measured. Colon adenoma cultures established from APCmin/+ mouse have developmental differences and β-catenin spatial localization compared to normal crypts. Quantitative data describing the effects of signalling pathways and proteins dynamics for both normal and adenomatous colon crypts is now within reach to inform a systems approach to colon crypt biology. PMID:26087250
Earthquake Source Parameters Relationships from 3D Rough Fault Dynamic Rupture
NASA Astrophysics Data System (ADS)
Yao, Q.; Day, S. M.; Shi, Z.
2015-12-01
Fault surface roughness has a strong influence on the distribution of stress around the fault, and affects the dynamics of the earthquake process. In particular, roughness influences the distribution of the parameters conventionally used to describe fault slip in, for example, kinematic modeling of strong ground motion. We explore the effect of the fault roughness on earthquake source parameters through the statistical analysis of a large suite of 3D rupture simulations. We have built a database of more than 1000 simulated dynamic ruptures based on different rough fault profiles and relative-strength (S) ratios, and have quantitatively analyzed the correlation between earthquake source parameter pairs.. In the subshear propagation-speed regime, we find the following relationships: (1) Rise time, total slip and peak slip rate each decrease with increasing roughness. (2) Rupture velocity is weakly positively related to slip, and the relationship is stronger with increasing roughness. We also explore how peak slip rate, rise time and different pairs of source parameters correlations are affected by fault roughness. This work may give useful guidance for use in kinematic rupture-source generators and help improve methods for ground strong motion prediction.
Bancelin, Stéphane; Decencière, Etienne; Machairas, Vaïa; Albert, Claire; Coradin, Thibaud; Schanne-Klein, Marie-Claire; Aimé, Carole
2014-09-21
The assembly of proteins into fibrillar structures is an important process that concerns different biological contexts, including molecular medicine and functional biomaterials. Engineering of hybrid biomaterials can advantageously provide synergetic interactions of the biopolymers with an inorganic component to ensure specific supramolecular organization and dynamics. To this aim, we designed hybrid systems associating collagen and surface-functionalized silica particles and we built a new strategy to investigate fibrillogenesis processes in such multicomponents systems, working at the crossroads of chemistry, physics and mathematics. The self-assembly process was investigated by bimodal multiphoton imaging coupling second harmonic generation (SHG) and 2 photon excited fluorescence (2PEF). The in-depth spatial characterization of the system was further achieved using the three-dimensional analysis of the SHG/2PEF data via mathematical morphology processing. Quantitation of collagen distribution around particles offers strong evidence that the chemically induced confinement of the protein on the silica nanosurfaces has a key influence on the spatial extension of fibrillogenesis. This new approach is unique in the information it can provide on 3D dynamic hybrid systems and may be extended to other associations of fibrillar molecules with optically responsive nano-objects. PMID:25058449
Agour, Mostafa; Falldorf, Claas; Bergmann, Ralf B
2016-06-27
We present a new method for the generation of a dynamic wave field with high space bandwidth product (SBP). The dynamic wave field is generated from several wave fields diffracted by a display which comprises multiple spatial light modulators (SLMs) each having a comparably low SBP. In contrast to similar approaches in stereoscopy, we describe how the independently generated wave fields can be coherently superposed. A major benefit of the scheme is that the display system may be extended to provide an even larger display. A compact experimental configuration which is composed of four phase-only SLMs to realize the coherent combination of independent wave fields is presented. Effects of important technical parameters of the display system on the wave field generated across the observation plane are investigated. These effects include, e.g., the tilt of the individual SLM and the gap between the active areas of multiple SLMs. As an example of application, holographic reconstruction of a 3D object with parallax effects is demonstrated. PMID:27410593
Bone grafts engineered from human adipose-derived stem cells in dynamic 3D-environments.
Declercq, Heidi A; De Caluwé, Tamara; Krysko, Olga; Bachert, Claus; Cornelissen, Maria J
2013-01-01
Modular tissue engineering (TE) is a promising alternative to overcome the limits in traditional TE. In the present study, adipose tissue derived stem cells (ADSC)-laden microcarriers are used as building blocks (microtissues) that self-assemble into macrotissues in a bottom-up approach. These bone grafts were compared with a classical top-down approach (scaffolds). This concept was compared with bone marrow derived stem cells (BMSC) as cell source. Cells were immunophenotypically analyzed, followed by 2D/3D osteogenic differentiation in static/dynamic conditions. The bone graft quality was evaluated by (immuno)histochemistry and gene expression. After 6 weeks of dynamic culturing, scaffolds were highly colonized although not in the center and the osteogenic gene expression was higher in contrast to static cultures. A cell-to-microcarrier ratio of 5 × 10(6) cells-0.09 g microcarriers leaded to aggregate formation resulting in microtissues with subsequent macrotissue formation. ADSC/BMSC on scaffolds showed a downregulation of Runx2 and collagen I, demonstrating the end-stage, in contrary to microcarriers, where an upregulation of Runx2, collagen I together with BSP and osteocalcin was observed. This paper showed that high quality bone grafts (2 cm³) can be engineered in a bottom-up approach with cell-laden microcarriers.
A digital holography set-up for 3D vortex flow dynamics
NASA Astrophysics Data System (ADS)
Lebon, Benoît; Perret, Gaële; Coëtmellec, Sébastien; Godard, Gilles; Gréhan, Gérard; Lebrun, Denis; Brossard, Jérôme
2016-06-01
In the present paper, a digital in-line holography (DIH) set-up, with a converging beam, is used to take three-dimensional (3D) velocity measurements of vortices. The vortices are formed periodically at the edges of a submerged horizontal plate submitted to regular waves. They take the form of vortex filaments that extend from side to side of the channel. They undergo strongly three-dimensional instability mechanisms that remain very complicated to characterize experimentally. The experiments are performed in a 10 × 0.3 × 0.3 m3 wave flume. The DIH set-up is performed using a modulated laser diode emitting at the wavelength of 640 nm and a lensless CCD camera. The beam crosses the channel side to side. To reveal the flow dynamics, 30-μm hydrogen bubbles are generated at the edge of the plate to serve as tracers. Their locations are recorded on the holograms multiple times to access the dynamics of the flow. This method leads to an accuracy in the order of 100 μm on the axial location. Those measurements have been validated with stereo-PIV measurements. A very good agreement is found on time-averaged velocity fields between the two techniques.
Chisholm, Kelsey; Miles, Devin; Rankine, Leith; Oldham, Mark
2015-05-15
Purpose: In optical-CT, the use of a refractively matched polyurethane solid-tank in place of a fluid bath has the potential to greatly increase practical convenience, reduce cost, and possibly improve the efficacy of flood corrections. This work investigates the feasibility of solid-tank optical-CT imaging for 3D dosimetry through computer simulation. Methods: A MATLAB ray-tracing simulation platform, ScanSim, was used to model a parallel-source telecentric optical-CT imaging system through a polyurethane solid-tank containing a central cylindrical hollow into which PRESAGE radiochromic dosimeters can be placed. A small amount of fluid fills the 1–5 mm gap between the dosimeter and the walls of the tank. The use of the solid-tank reduces the required amount of fluid by approximately 97%. To characterize the efficacy of solid-tank, optical-CT scanning simulations investigated sensitivity to refractive index (RI) mismatches between dosimeter, solid-tank, and fluid, for a variety of dosimeter (RI = 1.5–1.47) and fluid (RI = 1.55–1.0) combinations. Efficacy was evaluated through the usable radius (r{sub u}) metric, defined as the fraction of the radius of the dosimeter where measured dose is predicted to be within 2% of the ground truth entered into the simulation. Additional simulations examined the effect of increasing gap size (1–5 mm) between the dosimeter and solid-tank well. The effects of changing the lens tolerance (0.5°–5.0°) were also investigated. Results: As the RI mismatch between the dosimeter and solid-tank increased from 0 to 0.02, the usable radius decreased from 97.6% to 50.2%. The optimal fluid RI decreased nonlinearly from 1.5 to 1.34 as the mismatch increased and was up to 9% lower than the tank. Media mismatches between the dosimeter and solid-tank also exacerbate the effects of changing the gap size, with no easily quantifiable relationship with usable radius. Generally, the optimal fluid RI value increases as gap size increases and
Visualization of unsteady computational fluid dynamics
NASA Technical Reports Server (NTRS)
Haimes, Robert
1995-01-01
The current computing environment that most researchers are using for the calculation of 3D unsteady Computational Fluid Dynamic (CFD) results is a super-computer class machine. The Massively Parallel Processors (MPP's) such as the 160 node IBM SP2 at NAS and clusters of workstations acting as a single MPP (like NAS's SGI Power-Challenge array) provide the required computation bandwidth for CFD calculations of transient problems. Work is in progress on a set of software tools designed specifically to address visualizing 3D unsteady CFD results in these super-computer-like environments. The visualization is concurrently executed with the CFD solver. The parallel version of Visual3, pV3 required splitting up the unsteady visualization task to allow execution across a network of workstation(s) and compute servers. In this computing model, the network is almost always the bottleneck so much of the effort involved techniques to reduce the size of the data transferred between machines.
Dynamic stress-strain states for metal foams using a 3D cellular model
NASA Astrophysics Data System (ADS)
Zheng, Zhijun; Wang, Changfeng; Yu, Jilin; Reid, Stephen R.; Harrigan, John J.
2014-12-01
Dynamic uniaxial impact behaviour of metal foams using a 3D cell-based finite element model is examined. At sufficiently high loading rates, these materials respond by forming ‘shock or consolidation waves' (Tan et al., 2005a, 2005b). However, the existing dynamic experimental methods have limitations in fully informing this behaviour, particularly for solving boundary/initial value problems. Recently, the problem of the shock-like response of an open-cell foam has been examined by Barnes et al. (2014) using the Hugoniot-curve representations. The present study is somewhat complementary to that approach and additionally aims to provide insight into the ‘rate sensitivity' mechanism applicable to cellular materials. To assist our understanding of the ‘loading rate sensitivity' behaviour of cellular materials, a virtual ‘test' method based on the direct impact technique is explored. Following a continuum representation of the response, the strain field calculation method is employed to determine the local strains ahead of and behind the resulting ‘shock front'. The dynamic stress-strain states in the densification stage are found to be different from the quasi-static ones. It is evident that the constitutive behaviour of the cellular material is deformation-mode dependent. The nature of the ‘rate sensitivity' revealed for cellular materials in this paper is different from the strain-rate sensitivity of dense metals. It is shown that the dynamic stress-strain states behind a shock front of the cellular material lie on a unique curve and each point on the curve corresponds to a particular ‘impact velocity', referred as the velocity upstream of the shock in this study. The dynamic stress-strain curve is related to a layer-wise collapse mode, whilst the equivalent quasi-static curve is related to a random shear band collapse mode. The findings herein are aimed at improving the experimental test techniques used to characterise the rate-sensitivity behaviour
NASA Astrophysics Data System (ADS)
Duru, Kenneth; Dunham, Eric M.
2016-01-01
Dynamic propagation of shear ruptures on a frictional interface in an elastic solid is a useful idealization of natural earthquakes. The conditions relating discontinuities in particle velocities across fault zones and tractions acting on the fault are often expressed as nonlinear friction laws. The corresponding initial boundary value problems are both numerically and computationally challenging. In addition, seismic waves generated by earthquake ruptures must be propagated for many wavelengths away from the fault. Therefore, reliable and efficient numerical simulations require both provably stable and high order accurate numerical methods. We present a high order accurate finite difference method for: a) enforcing nonlinear friction laws, in a consistent and provably stable manner, suitable for efficient explicit time integration; b) dynamic propagation of earthquake ruptures along nonplanar faults; and c) accurate propagation of seismic waves in heterogeneous media with free surface topography. We solve the first order form of the 3D elastic wave equation on a boundary-conforming curvilinear mesh, in terms of particle velocities and stresses that are collocated in space and time, using summation-by-parts (SBP) finite difference operators in space. Boundary and interface conditions are imposed weakly using penalties. By deriving semi-discrete energy estimates analogous to the continuous energy estimates we prove numerical stability. The finite difference stencils used in this paper are sixth order accurate in the interior and third order accurate close to the boundaries. However, the method is applicable to any spatial operator with a diagonal norm satisfying the SBP property. Time stepping is performed with a 4th order accurate explicit low storage Runge-Kutta scheme, thus yielding a globally fourth order accurate method in both space and time. We show numerical simulations on band limited self-similar fractal faults revealing the complexity of rupture dynamics
NASA Astrophysics Data System (ADS)
Duru, K.; Dunham, E. M.; Bydlon, S. A.; Radhakrishnan, H.
2014-12-01
Dynamic propagation of shear ruptures on a frictional interface is a useful idealization of a natural earthquake.The conditions relating slip rate and fault shear strength are often expressed as nonlinear friction laws.The corresponding initial boundary value problems are both numerically and computationally challenging.In addition, seismic waves generated by earthquake ruptures must be propagated, far away from fault zones, to seismic stations and remote areas.Therefore, reliable and efficient numerical simulations require both provably stable and high order accurate numerical methods.We present a numerical method for:a) enforcing nonlinear friction laws, in a consistent and provably stable manner, suitable for efficient explicit time integration;b) dynamic propagation of earthquake ruptures along rough faults; c) accurate propagation of seismic waves in heterogeneous media with free surface topography.We solve the first order form of the 3D elastic wave equation on a boundary-conforming curvilinear mesh, in terms of particle velocities and stresses that are collocated in space and time, using summation-by-parts finite differences in space. The finite difference stencils are 6th order accurate in the interior and 3rd order accurate close to the boundaries. Boundary and interface conditions are imposed weakly using penalties. By deriving semi-discrete energy estimates analogous to the continuous energy estimates we prove numerical stability. Time stepping is performed with a 4th order accurate explicit low storage Runge-Kutta scheme. We have performed extensive numerical experiments using a slip-weakening friction law on non-planar faults, including recent SCEC benchmark problems. We also show simulations on fractal faults revealing the complexity of rupture dynamics on rough faults. We are presently extending our method to rate-and-state friction laws and off-fault plasticity.
NASA Astrophysics Data System (ADS)
Bartzke, Gerhard; Rogers, Benedict D.; Fourtakas, Georgios; Mokos, Athanasios; Huhn, Katrin
2016-04-01
The processes that cause the creation of a variety of sediment morphological features, e.g. laminated beds, ripples, or dunes, are based on the initial motion of individual sediment grains. However, with experimental techniques it is difficult to measure the flow characteristics, i.e., the velocity of the pore water flow in sediments, at a sufficient resolution and in a non-intrusive way. As a result, the role of fluid infiltration at the surface and in the interior affecting the initiation of motion of a sediment bed is not yet fully understood. Consequently, there is a strong need for numerical models, since these are capable of quantifying fluid driven sediment transport processes of complex sediment beds composed of irregular shapes. The numerical method Smoothed Particle Hydrodynamics (SPH) satisfies this need. As a meshless and Lagrangian technique, SPH is ideally suited to simulating flows in sediment beds composed of various grain shapes, but also flow around single grains at a high temporal and spatial resolution. The solver chosen is DualSPHysics (www.dual.sphysics.org) since this is validated for a range of flow conditions. For the present investigation a 3-D numerical flume model was generated using SPH with a length of 4.0 cm, a width of 0.05 cm and a height of 0.2 cm where mobile sediment particles were deposited in a recess. An experimental setup was designed to test sediment configurations composed of irregular grain shapes (grain diameter, D50=1000 μm). Each bed consisted of 3500 mobile objects. After the bed generation process, the entire domain was flooded with 18 million fluid particles. To drive the flow, an oscillating motion perpendicular to the bed was applied to the fluid, reaching a peak value of 0.3 cm/s, simulating 4 seconds of real time. The model results showed that flow speeds decreased logarithmically from the top of the domain towards the surface of the beds, indicating a fully developed boundary layer. Analysis of the fluid
Toward a 3D dynamic model of a faulty duplex ball bearing
NASA Astrophysics Data System (ADS)
Kogan, Gideon; Klein, Renata; Kushnirsky, Alex; Bortman, Jacob
2015-03-01
Bearings are vital components for safe and proper operation of machinery. Increasing efficiency of bearing diagnostics usually requires training of health and usage monitoring systems via expensive and time-consuming ground calibration tests. The main goal of this research, therefore, is to improve bearing dynamics modeling tools in order to reduce the time and budget needed to implement the health and usage monitoring approach. The proposed three-dimensional ball bearing dynamic model is based on the classic dynamic and kinematic equations. Interactions between the bodies are simulated using non-linear springs combined with dampers described by Hertz-type contact relation. The force friction is simulated using the hyperbolic-tangent function. The model allows simulation of a wide range of mechanical faults. It is validated by comparison to known bearing behavior and to experimental results. The model results are verified by demonstrating numerical convergence. The model results for the two cases of single and duplex angular ball bearings with axial deformation in the outer ring are presented. The qualitative investigation provides insight into bearing dynamics, the sensitivity study generalizes the qualitative findings for similar cases, and the comparison to the test results validates model reliability. The article demonstrates the variety of the cases that the 3D bearing model can simulate and the findings to which it may lead. The research allowed the identification of new patterns generated by single and duplex bearings with axially deformed outer race. It also enlightened the difference between single and duplex bearing manifestation. In the current research the dynamic model enabled better understanding of the physical behavior of the faulted bearings. Therefore, it is expected that the modeling approach has the potential to simplify and improve the development process of diagnostic algorithms. • A deformed outer race of a single axially loaded bearing is
3D Orbital Stability and Dynamic Environment of Asteroid 216 Kleopatra
NASA Astrophysics Data System (ADS)
Winter, Othon; Chanut, Thierry
A peculiar asteroid that might be the target of future space mission explorations is 216 Kleopatra, which has two small satellites and a peculiar dog-bone shape. Recent data processing showed the existence of a difference that can reach 25% for the dimensions of 216 Kleopatra between the radar observations and the light curves. We rebuild the shape of the asteroid 216 Kleopatra from these new data and estimate certain physical features by using the polyhedral model method. In our computations we use a code that avoids singularities from the line integrals of a homogeneous arbitrary shaped polyhedral source. This code evaluates the gravitational potential function and its first and second order derivatives. Then, we find the location of the and zero velocity curves. Finally, taking the rotation of asteroid 216 Kleopatra into consideration, the aims of this work is to analyze the stability against impact and the dynamics of numerical simulations of 3D initially equatorial and polar orbits near the body.
Monitoring an eruption fissure in 3D: video recording, particle image velocimetry and dynamics
NASA Astrophysics Data System (ADS)
Witt, Tanja; Walter, Thomas R.
2015-04-01
The processes during an eruption are very complex. To get a better understanding several parameters are measured. One of the measured parameters is the velocity of particles and patterns, as ash and emitted magma, and of the volcano itself. The resulting velocity field provides insights into the dynamics of a vent. Here we test our algorithm for 3 dimensional velocity fields on videos of the second fissure eruption of Bárdarbunga 2014. There we acquired videos from lava fountains of the main fissure with 2 high speed cameras with small angles between the cameras. Additionally we test the algorithm on videos from the geyser Strokkur, where we had 3 cameras and larger angles between the cameras. The velocity is calculated by a correlation in the Fourier space of contiguous images. Considering that we only have the velocity field of the surface smaller angles result in a better resolution of the existing velocity field in the near field. For general movements also larger angles can be useful, e.g. to get the direction, height and velocity of eruption clouds. In summary, it can be stated that 3D velocimetry can be used for several application and with different setup due to the application.
Dynamic implicit 3D adaptive mesh refinement for non-equilibrium radiation diffusion
B. Philip; Z. Wang; M.A. Berrill; M. Birke; M. Pernice
2014-04-01
The time dependent non-equilibrium radiation diffusion equations are important for solving the transport of energy through radiation in optically thick regimes and find applications in several fields including astrophysics and inertial confinement fusion. The associated initial boundary value problems that are encountered often exhibit a wide range of scales in space and time and are extremely challenging to solve. To efficiently and accurately simulate these systems we describe our research on combining techniques that will also find use more broadly for long term time integration of nonlinear multi-physics systems: implicit time integration for efficient long term time integration of stiff multi-physics systems, local control theory based step size control to minimize the required global number of time steps while controlling accuracy, dynamic 3D adaptive mesh refinement (AMR) to minimize memory and computational costs, Jacobian Free Newton–Krylov methods on AMR grids for efficient nonlinear solution, and optimal multilevel preconditioner components that provide level independent solver convergence.
An extensive 3D dislocation dynamics investigation of stage-I fatigue crack propagation
NASA Astrophysics Data System (ADS)
Déprés, C.; Prasad Reddy, G. V.; Robertson, C.; Fivel, M.
2014-12-01
Stage-I fatigue crack propagation is investigated using 3D discrete dislocation dynamics (DD) simulations. Slip-based propagation mechanisms and the role of the pre-existing slip band on the crack path are emphasized. Stage-I crack growth is found to be compatible with successive decohesion of the persistent slip band/matrix interface rather than a mere effect of plastic irreversibility. Corresponding crack tip slip displacement magnitude and the associated crack growth rate are evaluated quantitatively at various tip distances from the grain boundary. This shows that grain boundaries systematically amplify slip dispersion ahead of the crack tip and consequently, slow down the stage-I crack growth rate. The results help in developing an original crack propagation model, accounting for the boundary effects relevant to polycrystals. The crack growth trend is then evaluated from calculations of the energy changes due to crack length increments. It is shown that the crack necessarily propagates by increments smaller than 10 nm.
NASA Technical Reports Server (NTRS)
Folta, David; Bauer, Frank H. (Technical Monitor)
2001-01-01
The autonomous formation flying control algorithm developed by the Goddard Space Flight Center (GSFC) for the New Millennium Program (NMP) Earth Observing-1 (EO-1) mission is investigated for applicability to libration point orbit formations. In the EO-1 formation-flying algorithm, control is accomplished via linearization about a reference transfer orbit with a state transition matrix (STM) computed from state inputs. The effect of libration point orbit dynamics on this algorithm architecture is explored via computation of STMs using the flight proven code, a monodromy matrix developed from a N-body model of a libration orbit, and a standard STM developed from the gravitational and coriolis effects as measured at the libration point. A comparison of formation flying Delta-Vs calculated from these methods is made to a standard linear quadratic regulator (LQR) method. The universal 3-D approach is optimal in the sense that it can be accommodated as an open-loop or closed-loop control using only state information.
NASA Astrophysics Data System (ADS)
Hagelberg, Frank
2003-03-01
Computational results on atomic scattering between charged projectiles and transition metal target atoms are presented. This work aims at obtaining detailed information about charge, spin and energy transfer processes that occur between the interacting particles. An in-depth understanding of these phenomena is expected to provide a theoretical basis for the interpretation of various types of ion beam experiments, ranging from gas phase chromatography to spectroscopic observations of fast ions in ferromagnetic media. This contribution focuses on the scattering of light projectiles ranging from He to O, that are prepared in various initial charge states, by 3d transition metal atoms. The presented computations are performed in the framework of Electron Nuclear Dynamics (END)^1 theory which incorporates the coupling between electronic and nuclear degrees of freedom without reliance on the computationally cumbersome and frequently intractable determination of potential energy surfaces. In the present application of END theory to ion - transition metal atom scattering, a supermolecule approach is utilized in conjunction with a spin-unrestricted single determinantal wave function describing the electronic system. Integral scattering, charge and spin exchange cross sections are discussed as functions of the elementary parameters of the problem, such as projectile and target atomic numbers as well as projectile charge and initial kinetic energy. ^1 E.Deumens, A.Diz, R.Longo, Y.Oehrn, Rev.Mod.Phys. 66, 917 (1994)
A 3D Parallel Beam Dynamics Code for Modeling High Brightness Beams in Photoinjectors
Qiang, Ji; Lidia, S.; Ryne, R.D.; Limborg, C.; /SLAC
2006-02-13
In this paper we report on IMPACT-T, a 3D beam dynamics code for modeling high brightness beams in photoinjectors and rf linacs. IMPACT-T is one of the few codes used in the photoinjector community that has a parallel implementation, making it very useful for high statistics simulations of beam halos and beam diagnostics. It has a comprehensive set of beamline elements, and furthermore allows arbitrary overlap of their fields. It is unique in its use of space-charge solvers based on an integrated Green function to efficiently and accurately treat beams with large aspect ratio, and a shifted Green function to efficiently treat image charge effects of a cathode. It is also unique in its inclusion of energy binning in the space-charge calculation to model beams with large energy spread. Together, all these features make IMPACT-T a powerful and versatile tool for modeling beams in photoinjectors and other systems. In this paper we describe the code features and present results of IMPACT-T simulations of the LCLS photoinjectors. We also include a comparison of IMPACT-T and PARMELA results.
A 3d Parallel Beam Dynamics Code for Modeling High BrightnessBeams in Photoinjectors
Qiang, J.; Lidia, S.; Ryne, R.; Limborg, C.
2005-05-16
In this paper we report on IMPACT-T, a 3D beam dynamics code for modeling high brightness beams in photoinjectors and rf linacs. IMPACT-T is one of the few codes used in the photoinjector community that has a parallel implementation, making it very useful for high statistics simulations of beam halos and beam diagnostics. It has a comprehensive set of beamline elements, and furthermore allows arbitrary overlap of their fields. It is unique in its use of space-charge solvers based on an integrated Green function to efficiently and accurately treat beams with large aspect ratio, and a shifted Green function to efficiently treat image charge effects of a cathode. It is also unique in its inclusion of energy binning in the space-charge calculation to model beams with large energy spread. Together, all these features make IMPACT-T a powerful and versatile tool for modeling beams in photoinjectors and other systems. In this paper we describe the code features and present results of IMPACT-T simulations of the LCLS photoinjectors. We also include a comparison of IMPACT-T and PARMELA results.
NASA Astrophysics Data System (ADS)
Campbell, Nicholas
2014-11-01
The success of dielectric barrier discharge (DBD) plasma actuators as flow control devices in transducing electrical energy directly into near instantaneous fluid motion has been limited due to momentum loss near the wall. To increase the feasibility of these devices, they have been used to drive a channel flow, creating a jet under quiescent conditions. Electrostatic Fluid Accelerators (EFA) have also been shown to drive internal gas flows. The present work draws on the success of the DBD driven plasma channels, while exploring a new electrode configuration that stems from EFA designs, in order to actuate more of the bulk fluid. Major parameters, applied voltage and operating frequency as well as electrode gap and choice of electrode (material, shape, size); were experimentally investigated using Particle Image Velocimetry to obtain time averaged, 2D velocity fields. Results indicate significant variation of performance with these parameters and suggest that in comparison to surface DBD actuators an order magnitude improvement in efficiency is possible. Furthermore, the qualitative aspect of an electro-fluid dynamic jet shows greater versatility in application for use as both boundary layer flow control and driving internal gas flows.
3D deformation and dynamics of the human cadaver abdomen under seatbelt loading.
Lamielle, Sophie; Vezin, Philippe; Verriest, Jean-Pierre; Petit, Philippe; Trosseille, Xavier; Vallancien, Guy
2008-11-01
to be able to compare the load penetration characteristics to the results reported in the literature. The injury outcomes are provided and compared to all the published data. The PMHS sustained MAIS2-3 abdominal injuries in the low speed tests and MAIS2-4 injuries in the high speed tests. Finally, the dynamic 3D deformation of the abdominal wall was reconstructed and is provided for further validation of finite element models of the human abdomen.
Dynamical electron compressibility in the 3D topological insulator Bi2Se3
NASA Astrophysics Data System (ADS)
Inhofer, Andreas; Assaf, Badih; Wilmart, Quentin; Veyrat, Louis; Nowka, Christian; Dufouleur, Joseph; Giraud, Romain; Hampel, Silke; Buechner, Bernd; Fève, Gwendal; Berroir, Jean-Marc; Placais, Bernard
Measurements of the quantum capacitance cq, related to the electron compressibility χ =cq /e2 is a sensitive tool to probe the density of states. In a topological insulator (TI) the situation is enriched by the coexistence and the interplay of topologically protected surface states and massive bulk carriers. We investigate top-gate metal-oxyde-TI capacitors using Bi2Se3 thin crystals at GHz frequencies. These measurements provide insight into the compressibillity of such a two electron-fluid system. Furthermore, the dynamical response yields information about electron scattering properties in TIs. More specifically, in our measurements we track simultaneously the conductivity σ and the compressibility as a function of a DC-gate voltage. Using the Einstein relation σ =cq D , we have access to the gate dependence of the electron diffusion constant D (Vg) , a signature of the peculiar scattering mechanisms in TIs.
Possible migration front of gas-related fluid inferred from 3D seismic in the eastern Nankai Trough
NASA Astrophysics Data System (ADS)
Otsuka, H.; Morita, S.; Tanahashi, M.; Ashi, J.; Nagakubo, S.
2010-12-01
High resolution 3D seismic survey, “Tokai-oki to Kumano-nada”, was conducted for methane hydrate exploration in the eastern Nankai Trough by METI in 2002. Our study focuses on a series of accordion-shaped reflectors with horizontal axis of fold back. They are connected to the edge of BSRs and alternate their polarities at every fold back hinge. We call the reflectors “Foldback Reflectors (FBRs)” in this study. Sedimentary horizons are successive across these series of reflectors with no fault displacement as a general rule. FBR generally corresponds to lateral seismic facies boundary between BSR distribution area and outside of the BSR area. The formation beneath the BSR shows dimmed facies characterized by relatively low amplitude and lack of high frequency components in contrast to outside of the BSR area with normal facies. Seismic velocity analysis suggests that FBRs correspond to velocity boundaries, where the dimmed faceis below the BSR coinsides with relatively low velocity. The polarities of FBRs are also consistent with such velocity changes. Such dimmed facies with low velocity and low amplitude anomaly suggests effects of gas components in the pore water. In this area, FBRs are mostly developed in the well-stratified formation but not in the area of frequent fractures and the area of major lateral lithological change. The observed FBRs are clustered in northern slope of the uplifted outer ridge, whereas few FBRs are developed in the southern slope of the outer ridge with frequent compressive and strike-slip deformations related to major fault systems including the Kodaiba faults and the Tokai faults. The estimated strike directions of each FBRs are probably controlled by the dip direction of crossing formation. Another important character of FBRs is that it never crosses major unconformities into lower strata. In addition, high amplitude layers are sometimes recognized at hinges of foldbacks convex to the outside of the BSR area. These high
PLOT3D/AMES, APOLLO UNIX VERSION USING GMR3D (WITHOUT TURB3D)
NASA Technical Reports Server (NTRS)
Buning, P.
1994-01-01
PLOT3D is an interactive graphics program designed to help scientists visualize computational fluid dynamics (CFD) grids and solutions. Today, supercomputers and CFD algorithms can provide scientists with simulations of such highly complex phenomena that obtaining an understanding of the simulations has become a major problem. Tools which help the scientist visualize the simulations can be of tremendous aid. PLOT3D/AMES offers more functions and features, and has been adapted for more types of computers than any other CFD graphics program. Version 3.6b+ is supported for five computers and graphic libraries. Using PLOT3D, CFD physicists can view their computational models from any angle, observing the physics of problems and the quality of solutions. As an aid in designing aircraft, for example, PLOT3D's interactive computer graphics can show vortices, temperature, reverse flow, pressure, and dozens of other characteristics of air flow during flight. As critical areas become obvious, they can easily be studied more closely using a finer grid. PLOT3D is part of a computational fluid dynamics software cycle. First, a program such as 3DGRAPE (ARC-12620) helps the scientist generate computational grids to model an object and its surrounding space. Once the grids have been designed and parameters such as the angle of attack, Mach number, and Reynolds number have been specified, a "flow-solver" program such as INS3D (ARC-11794 or COS-10019) solves the system of equations governing fluid flow, usually on a supercomputer. Grids sometimes have as many as two million points, and the "flow-solver" produces a solution file which contains density, x- y- and z-momentum, and stagnation energy for each grid point. With such a solution file and a grid file containing up to 50 grids as input, PLOT3D can calculate and graphically display any one of 74 functions, including shock waves, surface pressure, velocity vectors, and particle traces. PLOT3D's 74 functions are organized into
PLOT3D/AMES, APOLLO UNIX VERSION USING GMR3D (WITH TURB3D)
NASA Technical Reports Server (NTRS)
Buning, P.
1994-01-01
PLOT3D is an interactive graphics program designed to help scientists visualize computational fluid dynamics (CFD) grids and solutions. Today, supercomputers and CFD algorithms can provide scientists with simulations of such highly complex phenomena that obtaining an understanding of the simulations has become a major problem. Tools which help the scientist visualize the simulations can be of tremendous aid. PLOT3D/AMES offers more functions and features, and has been adapted for more types of computers than any other CFD graphics program. Version 3.6b+ is supported for five computers and graphic libraries. Using PLOT3D, CFD physicists can view their computational models from any angle, observing the physics of problems and the quality of solutions. As an aid in designing aircraft, for example, PLOT3D's interactive computer graphics can show vortices, temperature, reverse flow, pressure, and dozens of other characteristics of air flow during flight. As critical areas become obvious, they can easily be studied more closely using a finer grid. PLOT3D is part of a computational fluid dynamics software cycle. First, a program such as 3DGRAPE (ARC-12620) helps the scientist generate computational grids to model an object and its surrounding space. Once the grids have been designed and parameters such as the angle of attack, Mach number, and Reynolds number have been specified, a "flow-solver" program such as INS3D (ARC-11794 or COS-10019) solves the system of equations governing fluid flow, usually on a supercomputer. Grids sometimes have as many as two million points, and the "flow-solver" produces a solution file which contains density, x- y- and z-momentum, and stagnation energy for each grid point. With such a solution file and a grid file containing up to 50 grids as input, PLOT3D can calculate and graphically display any one of 74 functions, including shock waves, surface pressure, velocity vectors, and particle traces. PLOT3D's 74 functions are organized into
NASA Astrophysics Data System (ADS)
Appelt, Veit; Shvetsov, Vladimir
2006-04-01
For projects concerning modification of urban structures or landscape, it is essential to have a visualisation before, during and after the planning. It conveys an impression of existing city structures or newly planned buildings roads, railways in 3D reality it helps to gain public acceptance. The design of such constructions makes high demands on geometry and planning technology. The construction project, as a 3D object, must therefore be assessed in whole and only this leads to a comprehensive evaluation of alignment, design and following up safety. On the basis of surveying and planning data, a 3D model fitted together of several information levels.
Grossberg, Stephen; Yazdanbakhsh, Arash
2005-06-01
The 3D LAMINART neural model is developed to explain how the visual cortex gives rise to 3D percepts of stratification, transparency, and neon color spreading in response to 2D pictures and 3D scenes. Such percepts are sensitive to whether contiguous image regions have the same contrast polarity and ocularity. The model predicts how like-polarity competition at V1 simple cells in layer 4 may cause these percepts when it interacts with other boundary and surface processes in V1, V2, and V4. The model also explains how: the Metelli Rules cause transparent percepts, bistable transparency percepts arise, and attention influences transparency reversal.
NASA Astrophysics Data System (ADS)
Li, Yingmin; Wang, Jiaxi; Clark, Melissa L.; Kubiak, Clifford P.; Xiong, Wei
2016-04-01
We report the first fourth-order 3D SFG spectroscopy of a monolayer of the catalyst Re(diCN-bpy)(CO)3Cl on a gold surface. Besides measuring the vibrational coherences of single vibrational modes, the fourth-order 3D SFG spectrum also measures the dynamics of interstate coherences and vibrational coherences states between two vibrational modes. By comparing the 3D SFG to the corresponding 2D and third-order 3D IR spectroscopy of the same molecules in solution, we found that the interstate coherences exist in both liquid and surface systems, suggesting that the interstate coherence is not disrupted by surface interactions. However, by analyzing the 3D spectral lineshape, we found that the interstate coherences also experience non-negligible homogenous dephasing dynamics that originate from surface interactions. This unique ability of determining interstate vibrational coherence dynamics of the molecular monolayer can help in understanding of how energy flows within surface catalysts and other molecular monolayers.
How the venetian blind percept emerges from the laminar cortical dynamics of 3D vision.
Cao, Yongqiang; Grossberg, Stephen
2014-01-01
The 3D LAMINART model of 3D vision and figure-ground perception is used to explain and simulate a key example of the Venetian blind effect and to show how it is related to other well-known perceptual phenomena such as Panum's limiting case. The model proposes how lateral geniculate nucleus (LGN) and hierarchically organized laminar circuits in cortical areas V1, V2, and V4 interact to control processes of 3D boundary formation and surface filling-in that simulate many properties of 3D vision percepts, notably consciously seen surface percepts, which are predicted to arise when filled-in surface representations are integrated into surface-shroud resonances between visual and parietal cortex. Interactions between layers 4, 3B, and 2/3 in V1 and V2 carry out stereopsis and 3D boundary formation. Both binocular and monocular information combine to form 3D boundary and surface representations. Surface contour surface-to-boundary feedback from V2 thin stripes to V2 pale stripes combines computationally complementary boundary and surface formation properties, leading to a single consistent percept, while also eliminating redundant 3D boundaries, and triggering figure-ground perception. False binocular boundary matches are eliminated by Gestalt grouping properties during boundary formation. In particular, a disparity filter, which helps to solve the Correspondence Problem by eliminating false matches, is predicted to be realized as part of the boundary grouping process in layer 2/3 of cortical area V2. The model has been used to simulate the consciously seen 3D surface percepts in 18 psychophysical experiments. These percepts include the Venetian blind effect, Panum's limiting case, contrast variations of dichoptic masking and the correspondence problem, the effect of interocular contrast differences on stereoacuity, stereopsis with polarity-reversed stereograms, da Vinci stereopsis, and perceptual closure. These model mechanisms have also simulated properties of 3D neon
How the venetian blind percept emerges from the laminar cortical dynamics of 3D vision.
Cao, Yongqiang; Grossberg, Stephen
2014-01-01
The 3D LAMINART model of 3D vision and figure-ground perception is used to explain and simulate a key example of the Venetian blind effect and to show how it is related to other well-known perceptual phenomena such as Panum's limiting case. The model proposes how lateral geniculate nucleus (LGN) and hierarchically organized laminar circuits in cortical areas V1, V2, and V4 interact to control processes of 3D boundary formation and surface filling-in that simulate many properties of 3D vision percepts, notably consciously seen surface percepts, which are predicted to arise when filled-in surface representations are integrated into surface-shroud resonances between visual and parietal cortex. Interactions between layers 4, 3B, and 2/3 in V1 and V2 carry out stereopsis and 3D boundary formation. Both binocular and monocular information combine to form 3D boundary and surface representations. Surface contour surface-to-boundary feedback from V2 thin stripes to V2 pale stripes combines computationally complementary boundary and surface formation properties, leading to a single consistent percept, while also eliminating redundant 3D boundaries, and triggering figure-ground perception. False binocular boundary matches are eliminated by Gestalt grouping properties during boundary formation. In particular, a disparity filter, which helps to solve the Correspondence Problem by eliminating false matches, is predicted to be realized as part of the boundary grouping process in layer 2/3 of cortical area V2. The model has been used to simulate the consciously seen 3D surface percepts in 18 psychophysical experiments. These percepts include the Venetian blind effect, Panum's limiting case, contrast variations of dichoptic masking and the correspondence problem, the effect of interocular contrast differences on stereoacuity, stereopsis with polarity-reversed stereograms, da Vinci stereopsis, and perceptual closure. These model mechanisms have also simulated properties of 3D neon
How the venetian blind percept emerges from the laminar cortical dynamics of 3D vision
Cao, Yongqiang; Grossberg, Stephen
2014-01-01
The 3D LAMINART model of 3D vision and figure-ground perception is used to explain and simulate a key example of the Venetian blind effect and to show how it is related to other well-known perceptual phenomena such as Panum's limiting case. The model proposes how lateral geniculate nucleus (LGN) and hierarchically organized laminar circuits in cortical areas V1, V2, and V4 interact to control processes of 3D boundary formation and surface filling-in that simulate many properties of 3D vision percepts, notably consciously seen surface percepts, which are predicted to arise when filled-in surface representations are integrated into surface-shroud resonances between visual and parietal cortex. Interactions between layers 4, 3B, and 2/3 in V1 and V2 carry out stereopsis and 3D boundary formation. Both binocular and monocular information combine to form 3D boundary and surface representations. Surface contour surface-to-boundary feedback from V2 thin stripes to V2 pale stripes combines computationally complementary boundary and surface formation properties, leading to a single consistent percept, while also eliminating redundant 3D boundaries, and triggering figure-ground perception. False binocular boundary matches are eliminated by Gestalt grouping properties during boundary formation. In particular, a disparity filter, which helps to solve the Correspondence Problem by eliminating false matches, is predicted to be realized as part of the boundary grouping process in layer 2/3 of cortical area V2. The model has been used to simulate the consciously seen 3D surface percepts in 18 psychophysical experiments. These percepts include the Venetian blind effect, Panum's limiting case, contrast variations of dichoptic masking and the correspondence problem, the effect of interocular contrast differences on stereoacuity, stereopsis with polarity-reversed stereograms, da Vinci stereopsis, and perceptual closure. These model mechanisms have also simulated properties of 3D neon
3D Visualization of "Frozen" Dynamic Magma Chambers in the Duluth Complex, Northeastern Minnesota
NASA Astrophysics Data System (ADS)
Peterson, D. M.; Hauck, S. A.
2005-12-01
The Mesoproterozoic Duluth Complex and associated intrusions of the Midcontinent Rift in northeastern Minnesota constitute one of the largest, semi-continuous, mafic intrusive complexes in the world, second only to the Bushveld Complex of South Africa. These rocks cover an arcuate area of over 5,000 square kilometers and give rise to two strong gravity anomalies (+50 & +70 mgal) that imply intrusive roots to more than 13 km depth. The geometry of three large mafic intrusions within the Duluth Complex have been modeled by the integration of field mapping and drill hole data with maps of gravity and magnetic anomalies. The igneous bodies include the South Kawishiwi, Partridge River, and Bald Eagle intrusions that collectively outcrop over an area of > 800 square kilometers. The South Kawishiwi and Partridge River intrusions host several billion tons of low-grade Cu-Ni-PGE mineralization near their base, while the geophysical expressions of the Bald Eagle intrusion have the same shape and dimensions as the "bulls eye" pattern of low velocity seismic reflection anomalies along the East Pacific Rise. These anomalies are interpreted to define regions of melt concentrations, i.e., active magma chambers. This suggests that the funnel-shaped Bald Eagle intrusion could be an example of a "frozen" dynamic magma chamber. In support of this analogy we note that the magmatic systems of intracontinental rifts, mid-ocean ridges, extensional regimes in back-arc environments, and ophiolites have a common characteristic: the emplacement of magma in extensional environments, and the common products in all four are varieties of layered intrusions, dikes and sills, and overlying volcanic rocks. 3D visualization of these intrusions is integral to the understanding of the Duluth Complex magmatic system and associated mineralization, and can be used as a proxy for study of similar systems, such as the Antarctic Ferrar dolerites, worldwide.
The 3-D dynamics of slab break-off and implications for continental collision zones
NASA Astrophysics Data System (ADS)
van Hunen, Jeroen; Allen, Mark
2010-05-01
Some of the world best studied mountain ranges are a result of continental collision, such as the Himalayas, Zagros mountains, and the Alps. Continental collision forms the last stage of the closure of an oceanic basin, and leads to the slow-down or complete cessation of the subduction process. Previously subducted slab material will experience a period of thermal warming (Gerya et al., 2004) and/or a larger tensile stress, and will eventually weaken, yield and sink into the mantle. This process has potentially important implications for the thermal and stress regime of the overlying convergence zone, and has been held responsible for various phenomena such as late-stage magmatism (Davies and von Blanckenburg, 1995) and surface uplift or depression (van der Meulen et al., 1998, Buiter et al., 2002). Even though the collision process itself is relatively short-lived compared to the preceding oceanic subduction, its remnants are often preserved, and probably provide a valuable window into the plate tectonic process during the Proterozoic and perhaps the Archaean (e.g. Calvert et al., 1995). The three-dimensional nature of this break-off process has previously been discussed with conceptual models. E.g. slab break-off has been suggested to propagate laterally through an advancing tear (Wortel and Spakman, 2000). In this study we present 3D numerical results of the evolution of slab break-off. We focus on the development and evolution of a laterally migrating slab tear, and present results on the sensitivity of this process to the geometry of the closing oceanic basin, the tensile stresses in and the rheological properties of the slab, and the thermal state of the surrounding mantle. By comparing our numerical results to previously published analogue results (Regard et al., 2004) and various tomographic, structural, and magmatic observations of well-studied subduction collision systems, we are able to extract valuable insights in to the dynamics and strength of
NASA Astrophysics Data System (ADS)
Pini, R.; Vandehey, N. T.; O'Neil, J.; Benson, S. M.
2015-12-01
We report results of an experimental investigation into the effects of small-scale (mm-cm) heterogeneities and hydrodynamic dispersion on miscible and immiscible displacements in a Berea Sandstone core. Pulse-radiotracer tests were carried out by measuring breakthrough curves at distinct flow rates and gas/water saturation ratios, while simultaneously imaging the internal displacement of the radioactive solution by [11C]PET. Dynamic multidimensional maps of the tracer concentration in the rock sample have been obtained with a spatial resolution of about 10 mm3 and provide evidence for significant macrodispersion effects caused by the presence of heterogeneities at the same scale. The numerical solution of the classic Advection-Dispersion Equation (ADE) applied in 1D form fails to describe the measured breakthrough curves and significantly overestimates longitudinal dispersivity. An excellent agreement with the experiments is attained by explicitly accounting for permeability heterogeneity, while reducing the contribution of "Fickian" dispersivity. Heterogeneity was introduced in the model by discretising the rock sample into independent parallel streamlines, which were generated based on a previously determined 3D permeability map, and by solving the 1D ADE for each of them. The use of streamlines is supported by direct quantitative observations from the PET scans; remarkably, this approach leads to an accurate representation of both the temporal behaviour and spatial distribution of the tracer concentration in the sample. It is shown that when the length-scale of permeability variations is similar in order as the size of the sample, the effect of the former can be as significant as hydrodynamic dispersion. The presence of a second immiscible fluid phase further complicates the flow field and, accordingly, the interpretation of the experiments. The ability to decouple these effects leads to the estimation of dispersion coefficients that aren't sample specific and
3D-seismic observations of Late Pleistocene glacial dynamics on the central West Greenland margin
NASA Astrophysics Data System (ADS)
Hofmann, Julia; Knutz, Paul; Cofaigh, Colm Ó.
2016-04-01
Fast-flowing ice streams and outlet glaciers exert a major control on glacial discharge from contemporary and palaeo ice sheets. Improving our understanding of the extent and dynamic behaviour of these palaeo-ice streams is therefore crucial for predictions of the response of ice sheets to present and future climate warming and the associated implications for global sea level. This poster presents results from two 3D-seismic surveys located on the shelf adjoining the Disko Bay trough-mouth fan (TMF), one of the largest glacial outlet systems in Greenland. Located at the seaward terminus of the c. 370 km long cross-shelf Disko Trough, the Disko Bay TMF was generated by highly efficient subglacial sediment delivery onto the continental slopes during repeated ice-stream advances. A variety of submarine glacial landform assemblages are recognised on the seabed reflecting past ice-stream activity presumably related to glacial-interglacial cycles. The 3D-seismic volumes cover the shallow banks located north and south of the Disko Trough. The focus of this study is the seabed and the uppermost stratigraphic interval associated with the Late Stage of TMF development, presumably covering the late Pleistocene (Hofmann et al., submitted). Seabed morphologies include multiple sets of ridges up to 20 m high that extend in NW-SE direction for c. 30 km, and cross-cutting curvilinear furrows with maximum lengths of c. 9 km and average depths of c. 4.5 m. Back-stepping, arcuate scarps facing NW define the shelf break on the northern survey, comprising average widths of c. 4.5 km and incision depths of c. 27.5 m. The large transverse ridge features on the southern survey are likely ice-marginal and are interpreted as terminal moraine ridges recording the existence of a shelf-edge terminating, grounded Late Weichselian ice sheet. The furrows, most prominent on the outer shelf adjoining the shallow banks and partly incising the moraine ridges, are interpreted as iceberg ploughmarks
NASA Astrophysics Data System (ADS)
Kluesner, J. W.; Silver, E. A.; Nale, S. M.; Bangs, N. L.; McIntosh, K. D.
2013-12-01
We employ a seismic meta-attribute workflow to detect and analyze probable faults and fluid-pathways in 3D within the sedimentary section offshore Southern Costa Rica. During the CRISP seismic survey in 2011 we collected an 11 x 55 km grid of 3D seismic reflection data and high-resolvability EM122 multibeam data, with coverage extending from the incoming plate to the outer-shelf. We mapped numerous seafloor seep indicators, with distributions ranging from the lower-slope to ~15 km landward of the shelf break [Kluesner et al., 2013, G3, doi:10.1002/ggge.20058; Silver et al., this meeting]. We used the OpendTect software package to calculate meta-attribute volumes from the 3D seismic data in order to detect and visualize seismic discontinuities in 3D. This methodology consists of dip-steered filtering to pre-condition the data, followed by combining a set of advanced dip-steered seismic attributes into a single object probability attribute using a user-trained neural-network pattern-recognition algorithm. The parameters of the advanced seismic attributes are set for optimal detection of the desired geologic discontinuity (e.g. faults or fluid-pathways). The product is a measure of probability for the desired target that ranges between 0 and 1, with 1 representing the highest probability. Within the sedimentary section of the CRISP survey the results indicate focused fluid-migration pathways along dense networks of intersecting normal faults with approximately N-S and E-W trends. This pattern extends from the middle slope to the outer-shelf region. Dense clusters of fluid-migration pathways are located above basement highs and deeply rooted reverse faults [see Bangs et al., this meeting], including a dense zone of fluid-pathways imaged below IODP Site U1413. In addition, fault intersections frequently show an increased signal of fluid-migration and these zones may act as major conduits for fluid-flow through the sedimentary cover. Imaged fluid pathways root into high
Multiplexing encoding method for full-color dynamic 3D holographic display.
Xue, Gaolei; Liu, Juan; Li, Xin; Jia, Jia; Zhang, Zhao; Hu, Bin; Wang, Yongtian
2014-07-28
The multiplexing encoding method is proposed and demonstrated for reconstructing colorful images accurately by using single phase-only spatial light modulator (SLM). It will encode the light waves at different wavelengths into one pure-phase hologram at the same time based on the analytic formulas. The three-dimensional (3D) images can be reconstructed clearly when the light waves at different wavelengths are incident into the encoding hologram. Numerical simulations and optical experiments for 2D and 3D colorful images are performed. The results show that the colorful reconstructed images with high quality are achieved successfully. The proposed multiplexing method is a simple and fast encoding approach and the size of the system is small and compact. It is expected to be used for realizing full-color 3D holographic display in future.
Parra, J.O.; Collier, H.A.; Owen, T.E.
1997-06-01
In low porosity, low permeability zones, natural fractures are the primary source of permeability which affect both production and injection of fluids. The open fractures do not contribute much to porosity, but they provide an increased drainage network to any porosity. They also may connect the borehole to remote zones of better reservoir characteristics. An important approach to characterizing the fracture orientation and fracture permeability of reservoir formations is one based on the effects of such conditions on the propagation of acoustic and seismic waves in the rock. The project is a study directed toward the evaluation of acoustic logging and 3D-seismic measurement techniques as well as fluid flow and transport methods for mapping permeability anisotropy and other petrophysical parameters for the understanding of the reservoir fracture systems and associated fluid dynamics. The principal application of these measurement techniques and methods is to identify and investigate the propagation characteristics of acoustic and seismic waves in the Twin Creek hydrocarbon reservoir owned by Union Pacific Resources (UPR) and to characterize the fracture permeability distribution using production data. This site is located in the overthrust area of Utah and Wyoming. UPR drilled six horizontal wells, and presently UPR has two rigs running with many established drill hole locations. In addition, there are numerous vertical wells that exist in the area as well as 3D seismic surveys. Each horizontal well contains full FMS logs and MWD logs, gamma logs, etc.
3D time-lapse analysis of Rab11/FIP5 complex: spatiotemporal dynamics during apical lumen formation.
Mangan, Anthony; Prekeris, Rytis
2015-01-01
Fluorescent imaging of fixed cells grown in two-dimensional (2D) cultures is one of the most widely used techniques for observing protein localization and distribution within cells. Although this technique can also be applied to polarized epithelial cells that form three-dimensional (3D) cysts when grown in a Matrigel matrix suspension, there are still significant limitations in imaging cells fixed at a particular point in time. Here, we describe the use of 3D time-lapse imaging of live cells to observe the dynamics of apical membrane initiation site (AMIS) formation and lumen expansion in polarized epithelial cells. PMID:25800842
NASA Astrophysics Data System (ADS)
Lu, Y. W.; Liu, C. S.; Su, C. C.; Hsu, H. H.; Chen, Y. H.
2015-12-01
This study utilizes both chirp sonar images and coring results to investigate the unstable seafloor strata east of the Fangliao Submarine Canyon offshore southwestern Taiwan. We have constructed 3D chirp sonar images from a densely surveyed block to trace the attitude of an acoustic transparent layer and features caused by fluid activities. Based on the distribution of this transparent layer and fluid-related features, we suggest that this transparent layer forms a pathway for fluid migration which induces fluid-related characters such as acoustic blanking and fluid chimneys in the 3D chirp sonar images. Cored seafloor samples are used in this study to investigate the sediment compositions. The 210Pb activity profiles of the cores show oscillating and unsteady values at about 20~25 cm from core top. The bulk densities of the core samples in the same section (about 20~25 cm from core top) give values lower than those at deeper parts of the cores. These results indicate that the water content is much higher in the shallow sediments than in the deeper strata. From core sample analyses, we deduce that the local sediments are disturbed by liquefaction. From the analyses of 3D chirp sonar images and core data, we suggest that the seafloor east of the Fangliao Submarine Canyon is in an unstable condition, if disturbed by earthquakes, submarine landslides and gravity flows could be easily triggered and cause some geohazards, like breaking submarine cables during the 2006 Pingtung earthquake event.
Dynamics of electron emission in double photoionization processes near the krypton 3d threshold
NASA Astrophysics Data System (ADS)
Penent, F.; Sheinerman, S.; Andric, L.; Lablanquie, P.; Palaudoux, J.; Becker, U.; Braune, M.; Viefhaus, J.; Eland, J. H. D.
2008-02-01
Two-electron emission following photoabsorption near the Kr 3d threshold is investigated both experimentally and theoretically. On the experimental side, electron/electron coincidences using a magnetic bottle time-of-flight spectrometer allow us to observe the complete double photo ionization (DPI) continua of selected Kr2+ final states, and to see how these continua are affected by resonant processes in the vicinity of the Kr 3d threshold. The analysis is based on a quantum mechanical approach that takes into account the contribution of three different processes: (A) Auger decay of the inner 3d vacancy with the associated post-collision interaction (PCI) effects, (B) capture of slow photoelectrons into discrete states followed by valence multiplet decay (VMD) of the excited ionic states and (C) valence shell DPI. The dominant process for each Kr2+(4p-2) final state is the photoionization of the inner shell followed by Auger decay of the 3d vacancies. Moreover, for the 4p-2(3P) and 4p-2(1D) final ionic states an important contribution comes from the processes of slow photoelectron capture followed by VMD as well as from double ionization of the outer shell involving also VMD.
NASA Astrophysics Data System (ADS)
Chirayath, V.
2014-12-01
Fluid Lensing is a theoretical model and algorithm I present for fluid-optical interactions in turbulent flows as well as two-fluid surface boundaries that, when coupled with an unique computer vision and image-processing pipeline, may be used to significantly enhance the angular resolution of a remote sensing optical system with applicability to high-resolution 3D imaging of subaqueous regions and through turbulent fluid flows. This novel remote sensing technology has recently been implemented on a quadcopter-based UAS for imaging shallow benthic systems to create the first dataset of a biosphere with unprecedented sub-cm-level imagery in 3D over areas as large as 15 square kilometers. Perturbed two-fluid boundaries with different refractive indices, such as the surface between the ocean and air, may be exploited for use as lensing elements for imaging targets on either side of the interface with enhanced angular resolution. I present theoretical developments behind Fluid Lensing and experimental results from its recent implementation for the Reactive Reefs project to image shallow reef ecosystems at cm scales. Preliminary results from petabyte-scale aerial survey efforts using Fluid Lensing to image at-risk coral reefs in American Samoa (August, 2013) show broad applicability to large-scale automated species identification, morphology studies and reef ecosystem characterization for shallow marine environments and terrestrial biospheres, of crucial importance to understanding climate change's impact on coastal zones, global oxygen production and carbon sequestration.
Graph-Based Compression of Dynamic 3D Point Cloud Sequences.
Thanou, Dorina; Chou, Philip A; Frossard, Pascal
2016-04-01
This paper addresses the problem of compression of 3D point cloud sequences that are characterized by moving 3D positions and color attributes. As temporally successive point cloud frames share some similarities, motion estimation is key to effective compression of these sequences. It, however, remains a challenging problem as the point cloud frames have varying numbers of points without explicit correspondence information. We represent the time-varying geometry of these sequences with a set of graphs, and consider 3D positions and color attributes of the point clouds as signals on the vertices of the graphs. We then cast motion estimation as a feature-matching problem between successive graphs. The motion is estimated on a sparse set of representative vertices using new spectral graph wavelet descriptors. A dense motion field is eventually interpolated by solving a graph-based regularization problem. The estimated motion is finally used for removing the temporal redundancy in the predictive coding of the 3D positions and the color characteristics of the point cloud sequences. Experimental results demonstrate that our method is able to accurately estimate the motion between consecutive frames. Moreover, motion estimation is shown to bring a significant improvement in terms of the overall compression performance of the sequence. To the best of our knowledge, this is the first paper that exploits both the spatial correlation inside each frame (through the graph) and the temporal correlation between the frames (through the motion estimation) to compress the color and the geometry of 3D point cloud sequences in an efficient way.
Fluid dynamics in developmental biology: moving fluids that shape ontogeny
Cartwright, Julyan H.E.; Piro, Oreste; Tuval, Idan
2009-01-01
Human conception, indeed fertilization in general, takes place in a fluid, but what role does fluid dynamics have during the subsequent development of an organism? It is becoming increasingly clear that the number of genes in the genome of a typical organism is not sufficient to specify the minutiae of all features of its ontogeny. Instead, genetics often acts as a choreographer, guiding development but leaving some aspects to be controlled by physical and chemical means. Fluids are ubiquitous in biological systems, so it is not surprising that fluid dynamics should play an important role in the physical and chemical processes shaping ontogeny. However, only in a few cases have the strands been teased apart to see exactly how fluid forces operate to guide development. Here, we review instances in which the hand of fluid dynamics in developmental biology is acknowledged, both in human development and within a wider biological context, together with some in which fluid dynamics is notable but whose workings have yet to be understood, and we provide a fluid dynamicist’s perspective on possible avenues for future research. PMID:19794816
NASA Astrophysics Data System (ADS)
Soria, J.; Atkinson, C.
2008-07-01
Most unsteady and/or turbulent flows of geophysical and engineering interest have a highly three-dimensional (3D) complex topology and their experimental investigation is in pressing need of quantitative velocity measurement methods that are robust and can provide instantaneous 3C-3D velocity field data over a significant volumetric domain of the flow. This paper introduces and demonstrates a new method that uses multiple digital CCD array cameras to record in-line digital holograms of the same volume of seed particles from multiple orientations. This technique uses the same basic equipment as Tomo-PIV minus the camera lenses, it overcomes the depth-of-field problem of digital in-line holography and does not require the complex optical calibration of Tomo-PIV. The digital sensors can be oriented in an optimal manner to overcome the depth-of-field limitation of in-line holograms recorded using digital CCD or CMOS array cameras, resulting in a 3D reconstruction of the seed particles within the volume of interest, which can subsequently be analysed using 3D cross-correlation PIV analysis to yield a 3C-3D velocity field. A demonstration experiment of Tomo-HPIV using uniform translation with nominally 11 µm diameter seed particles shows that the 3D displacement derived from 3D cross-correlation Tomo-HPIV analysis can be measured within 5% of the imposed uniform translation, where the imposed uniform translation has an estimated standard uncertainty of 4.3%. So this paper proposes a multi-camera digital holographic imaging 3C-3D PIV method, which is identified as tomographic digital holographic PIV or Tomo-HPIV.
2008-01-01
The author provides a critical overview of three-dimensional (3-D) virtual worlds and “serious gaming” that are currently being developed and used in healthcare professional education and medicine. The relevance of this e-learning innovation for teaching students and professionals is debatable and variables influencing adoption, such as increased knowledge, self-directed learning, and peer collaboration, by academics, healthcare professionals, and business executives are examined while looking at various Web 2.0/3.0 applications. There is a need for more empirical research in order to unearth the pedagogical outcomes and advantages associated with this e-learning technology. A brief description of Roger’s Diffusion of Innovations Theory and Siemens’ Connectivism Theory for today’s learners is presented as potential underlying pedagogical tenets to support the use of virtual 3-D learning environments in higher education and healthcare. PMID:18762473
Motion field estimation for a dynamic scene using a 3D LiDAR.
Li, Qingquan; Zhang, Liang; Mao, Qingzhou; Zou, Qin; Zhang, Pin; Feng, Shaojun; Ochieng, Washington
2014-09-09
This paper proposes a novel motion field estimation method based on a 3D light detection and ranging (LiDAR) sensor for motion sensing for intelligent driverless vehicles and active collision avoidance systems. Unlike multiple target tracking methods, which estimate the motion state of detected targets, such as cars and pedestrians, motion field estimation regards the whole scene as a motion field in which each little element has its own motion state. Compared to multiple target tracking, segmentation errors and data association errors have much less significance in motion field estimation, making it more accurate and robust. This paper presents an intact 3D LiDAR-based motion field estimation method, including pre-processing, a theoretical framework for the motion field estimation problem and practical solutions. The 3D LiDAR measurements are first projected to small-scale polar grids, and then, after data association and Kalman filtering, the motion state of every moving grid is estimated. To reduce computing time, a fast data association algorithm is proposed. Furthermore, considering the spatial correlation of motion among neighboring grids, a novel spatial-smoothing algorithm is also presented to optimize the motion field. The experimental results using several data sets captured in different cities indicate that the proposed motion field estimation is able to run in real-time and performs robustly and effectively.
Motion Field Estimation for a Dynamic Scene Using a 3D LiDAR
Li, Qingquan; Zhang, Liang; Mao, Qingzhou; Zou, Qin; Zhang, Pin; Feng, Shaojun; Ochieng, Washington
2014-01-01
This paper proposes a novel motion field estimation method based on a 3D light detection and ranging (LiDAR) sensor for motion sensing for intelligent driverless vehicles and active collision avoidance systems. Unlike multiple target tracking methods, which estimate the motion state of detected targets, such as cars and pedestrians, motion field estimation regards the whole scene as a motion field in which each little element has its own motion state. Compared to multiple target tracking, segmentation errors and data association errors have much less significance in motion field estimation, making it more accurate and robust. This paper presents an intact 3D LiDAR-based motion field estimation method, including pre-processing, a theoretical framework for the motion field estimation problem and practical solutions. The 3D LiDAR measurements are first projected to small-scale polar grids, and then, after data association and Kalman filtering, the motion state of every moving grid is estimated. To reduce computing time, a fast data association algorithm is proposed. Furthermore, considering the spatial correlation of motion among neighboring grids, a novel spatial-smoothing algorithm is also presented to optimize the motion field. The experimental results using several data sets captured in different cities indicate that the proposed motion field estimation is able to run in real-time and performs robustly and effectively. PMID:25207868
Nitrogen dynamics in the Hyporheic zones of complex 3-D bedforms
NASA Astrophysics Data System (ADS)
Zheng, L.; Cardenas, M. B.; Chen, X.
2015-12-01
The hyporheic zone (HZ) is a biogeochemically active zone that hosts the coupled reactions of organic carbon oxidation, nitrification, and denitrification. These N transformations could either produce or consume NO3－ and thus the HZ could serve as a NO3－sink or source in the fluvial system. The reactants within the hyporheic zone are transported through advection by flow induced by bedform topography. However, most previous studies have focused on two-dimensional (2-D) and simple bedforms. Recent studies showed that even a simple 3-D bedform would have a higher hyporheic flux and a slightly larger volume or exchange zone depth, and thus a different residence time compared to its equivalent 2-D bedform. This implies that the competition between reactant supply and demand for the 3-D bedforms might be different from 2-D bedforms. In this study we will investigate the ecological role of HZ with much more complex and more natural 3-D bedforms through numerical simulations. We are investigating synthetic but realistic complex bedforms considering the superimposition of smaller dunes upon larger dunes. The goal of the study is improve our understanding and the prediction of the ecological function of HZ as a nitrate sink or source for a natural system.
Kinetic foundations of relativistic dissipative fluid dynamics
NASA Astrophysics Data System (ADS)
Denicol, G. S.
2014-12-01
In this contribution we discuss in detail the most widespread formalisms employed to derive relativistic dissipative fluid dynamics from the Boltzmann equation: Chapman-Enskog expansion and Israel-Stewart theory. We further point out the drawbacks of each theory and explain possible ways to circumvent them. Recent developments in the derivation of fluid dynamics from the Boltzmann equation are also discussed.
HYDRA, A finite element computational fluid dynamics code: User manual
Christon, M.A.
1995-06-01
HYDRA is a finite element code which has been developed specifically to attack the class of transient, incompressible, viscous, computational fluid dynamics problems which are predominant in the world which surrounds us. The goal for HYDRA has been to achieve high performance across a spectrum of supercomputer architectures without sacrificing any of the aspects of the finite element method which make it so flexible and permit application to a broad class of problems. As supercomputer algorithms evolve, the continuing development of HYDRA will strive to achieve optimal mappings of the most advanced flow solution algorithms onto supercomputer architectures. HYDRA has drawn upon the many years of finite element expertise constituted by DYNA3D and NIKE3D Certain key architectural ideas from both DYNA3D and NIKE3D have been adopted and further improved to fit the advanced dynamic memory management and data structures implemented in HYDRA. The philosophy for HYDRA is to focus on mapping flow algorithms to computer architectures to try and achieve a high level of performance, rather than just performing a port.
Petroll, W. Matthew; Ma, Lisha; Kim, Areum; Ly, Linda; Vishwanath, Mridula
2009-01-01
The goal of this study was to determine the morphological and sub-cellular mechanical effects of Rac activation on fibroblasts within 3-D collagen matrices. Corneal fibroblasts were plated at low density inside 100 μm thick fibrillar collagen matrices and cultured for 1 to 2 days in serum-free media. Time-lapse imaging was then performed using Nomarski DIC. After an acclimation period, perfusion was switched to media containing PDGF. In some experiments, Y-27632 or blebbistatin were used to inhibit Rho-kinase (ROCK) or myosin II, respectively. PDGF activated Rac and induced cell spreading, which resulted in an increase in cell length, cell area, and the number of pseudopodial processes. Tractional forces were generated by extending pseudopodia, as indicated by centripetal displacement and realignment of collagen fibrils. Interestingly, the pattern of pseudopodial extension and local collagen fibril realignment was highly dependent upon the initial orientation of fibrils at the leading edge. Following ROCK or myosin II inhibition, significant ECM relaxation was observed, but small displacements of collagen fibrils continued to be detected at the tips of pseudopodia. Taken together, the data suggests that during Rac-induced cell spreading within 3-D matrices, there is a shift in the distribution of forces from the center to the periphery of corneal fibroblasts. ROCK mediates the generation of large myosin II-based tractional forces during cell spreading within 3-D collagen matrices, however residual forces can be generated at the tips of extending pseudopodia that are both ROCK and myosin II-independent. PMID:18452153
Frega, Monica; Tedesco, Mariateresa; Massobrio, Paolo; Pesce, Mattia; Martinoia, Sergio
2014-01-01
Despite the extensive use of in-vitro models for neuroscientific investigations and notwithstanding the growing field of network electrophysiology, all studies on cultured cells devoted to elucidate neurophysiological mechanisms and computational properties, are based on 2D neuronal networks. These networks are usually grown onto specific rigid substrates (also with embedded electrodes) and lack of most of the constituents of the in-vivo like environment: cell morphology, cell-to-cell interaction and neuritic outgrowth in all directions. Cells in a brain region develop in a 3D space and interact with a complex multi-cellular environment and extracellular matrix. Under this perspective, 3D networks coupled to micro-transducer arrays, represent a new and powerful in-vitro model capable of better emulating in-vivo physiology. In this work, we present a new experimental paradigm constituted by 3D hippocampal networks coupled to Micro-Electrode-Arrays (MEAs) and we show how the features of the recorded network dynamics differ from the corresponding 2D network model. Further development of the proposed 3D in-vitro model by adding embedded functionalized scaffolds might open new prospects for manipulating, stimulating and recording the neuronal activity to elucidate neurophysiological mechanisms and to design bio-hybrid microsystems. PMID:24976386
NASA Technical Reports Server (NTRS)
Biedron, Robert T.; Carlson, Jan-Renee; Derlaga, Joseph M.; Gnoffo, Peter A.; Hammond, Dana P.; Jones, William T.; Kleb, Bil; Lee-Rausch, Elizabeth M.; Nielsen, Eric J.; Park, Michael A.; Rumsey, Christopher L.; Thomas, James L.; Wood, William A.
2015-01-01
This manual describes the installation and execution of FUN3D version 12.7, including optional dependent packages. FUN3D is a suite of computational fluid dynamics simulation and design tools that uses mixed-element unstructured grids in a large number of formats, including structured multiblock and overset grid systems. A discretely-exact adjoint solver enables efficient gradient-based design and grid adaptation to reduce estimated discretization error. FUN3D is available with and without a reacting, real-gas capability. This generic gas option is available only for those persons that qualify for its beta release status.
NASA Technical Reports Server (NTRS)
Biedron, Robert T.; Carlson, Jan-Renee; Derlaga, Joseph M.; Gnoffo, Peter A.; Hammond, Dana P.; Jones, William T.; Kleb, Bill; Lee-Rausch, Elizabeth M.; Nielsen, Eric J.; Park, Michael A.; Rumsey, Christopher L.; Thomas, James L.; Wood, William A.
2016-01-01
This manual describes the installation and execution of FUN3D version 13.0, including optional dependent packages. FUN3D is a suite of computational fluid dynamics simulation and design tools that uses mixed-element unstructured grids in a large number of formats, including structured multiblock and overset grid systems. A discretely-exact adjoint solver enables efficient gradient-based design and grid adaptation to reduce estimated discretization error. FUN3D is available with and without a reacting, real-gas capability. This generic gas option is available only for those persons that qualify for its beta release status.
NASA Technical Reports Server (NTRS)
Biedron, Robert T.; Derlaga, Joseph M.; Gnoffo, Peter A.; Hammond, Dana P.; Jones, William T.; Kleb, William L.; Lee-Rausch, Elizabeth M.; Nielsen, Eric J.; Park, Michael A.; Rumsey, Christopher L.; Thomas, James L.; Wood, William A.
2015-01-01
This manual describes the installation and execution of FUN3D version 12.6, including optional dependent packages. FUN3D is a suite of computational fluid dynamics simulation and design tools that uses mixed-element unstructured grids in a large number of formats, including structured multiblock and overset grid systems. A discretely-exact adjoint solver enables efficient gradient-based design and grid adaptation to reduce estimated discretization error. FUN3D is available with and without a reacting, real-gas capability. This generic gas option is available only for those persons that qualify for its beta release status.
NASA Technical Reports Server (NTRS)
Biedron, Robert T.; Carlson, Jan-Renee; Derlaga, Joseph M.; Gnoffo, Peter A.; Hammond, Dana P.; Jones, William T.; Kleb, Bil; Lee-Rausch, Elizabeth M.; Nielsen, Eric J.; Park, Michael A.; Rumsey, Christopher L.; Thomas, James L.; Wood, William A.
2016-01-01
This manual describes the installation and execution of FUN3D version 12.9, including optional dependent packages. FUN3D is a suite of computational fluid dynamics simulation and design tools that uses mixed-element unstructured grids in a large number of formats, including structured multiblock and overset grid systems. A discretely-exact adjoint solver enables efficient gradient-based design and grid adaptation to reduce estimated discretization error. FUN3D is available with and without a reacting, real-gas capability. This generic gas option is available only for those persons that qualify for its beta release status.
NASA Technical Reports Server (NTRS)
Biedron, Robert T.; Carlson, Jan-Renee; Derlaga, Joseph M.; Gnoffo, Peter A.; Hammond, Dana P.; Jones, William T.; Kleb, Bil; Lee-Rausch, Elizabeth M.; Nielsen, Eric J.; Park, Michael A.; Rumsey, Christopher L.; Thomas, James L.; Wood, William A.
2015-01-01
This manual describes the installation and execution of FUN3D version 12.8, including optional dependent packages. FUN3D is a suite of computational fluid dynamics simulation and design tools that uses mixed-element unstructured grids in a large number of formats, including structured multiblock and overset grid systems. A discretely-exact adjoint solver enables efficient gradient-based design and grid adaptation to reduce estimated discretization error. FUN3D is available with and without a reacting, real-gas capability. This generic gas option is available only for those persons that qualify for its beta release status.
NASA Technical Reports Server (NTRS)
Biedron, Robert T.; Derlaga, Joseph M.; Gnoffo, Peter A.; Hammond, Dana P.; Jones, William T.; Kleb, Bil; Lee-Rausch, Elizabeth M.; Nielsen, Eric J.; Park, Michael A.; Rumsey, Christopher L.; Thomas, James L.; Wood, William A.
2014-01-01
This manual describes the installation and execution of FUN3D version 12.4, including optional dependent packages. FUN3D is a suite of computational fluid dynamics simulation and design tools that uses mixedelement unstructured grids in a large number of formats, including structured multiblock and overset grid systems. A discretely-exact adjoint solver enables efficient gradient-based design and grid adaptation to reduce estimated discretization error. FUN3D is available with and without a reacting, real-gas capability. This generic gas option is available only for those persons that qualify for its beta release status.
Bertoglio, Cristóbal; Barber, David; Gaddum, Nicholas; Valverde, Israel; Rutten, Marcel; Beerbaum, Philipp; Moireau, Philippe; Hose, Rodney; Gerbeau, Jean-Frédéric
2014-03-21
We consider the problem of estimating the stiffness of an artery wall using a data assimilation method applied to a 3D fluid-structure interaction (FSI) model. Recalling previous works, we briefly present the FSI model, the data assimilation procedure and the segmentation algorithm. We present then two examples of the procedure using real data. First, we estimate the stiffness distribution of a silicon rubber tube from image data. Second, we present the estimation of aortic wall stiffness from real clinical data.
NASA Astrophysics Data System (ADS)
Kim, Ho Jun; Lee, Hae June
2016-06-01
The wide applicability of capacitively coupled plasma (CCP) deposition has increased the interest in developing comprehensive numerical models, but CCP imposes a tremendous computational cost when conducting a transient analysis in a three-dimensional (3D) model which reflects the real geometry of reactors. In particular, the detailed flow features of reactive gases induced by 3D geometric effects need to be considered for the precise calculation of radical distribution of reactive species. Thus, an alternative inclusive method for the numerical simulation of CCP deposition is proposed to simulate a two-dimensional (2D) CCP model based on the 3D gas flow results by simulating flow, temperature, and species fields in a 3D space at first without calculating the plasma chemistry. A numerical study of a cylindrical showerhead-electrode CCP reactor was conducted for particular cases of SiH4/NH3/N2/He gas mixture to deposit a hydrogenated silicon nitride (SiN x H y ) film. The proposed methodology produces numerical results for a 300 mm wafer deposition reactor which agree very well with the deposition rate profile measured experimentally along the wafer radius.
Heart wall motion analysis by dynamic 3D strain rate imaging from tissue Doppler echocardiography
NASA Astrophysics Data System (ADS)
Hastenteufel, Mark; Wolf, Ivo; de Simone, Raffaele; Mottl-Link, Sibylle; Meinzer, Hans-Peter
2002-04-01
The knowledge about the complex three-dimensional (3D) heart wall motion pattern, particular in the left ventricle, provides valuable information about potential malfunctions, e.g., myocardial ischemia. Nowadays, echocardiography (cardiac ultrasound) is the predominant technique for evaluation of cardiac function. Beside morphology, tissue velocities can be obtained by Doppler techniques (tissue Doppler imaging, TDI). Strain rate imaging (SRI) is a new technique to diagnose heart vitality. It provides information about the contraction ability of the myocardium. Two-dimensional color Doppler echocardiography is still the most important clinical method for estimation of morphology and function. Two-dimensional methods leads to a lack of information due to the three-dimensional overall nature of the heart movement. Due to this complex three-dimensional motion pattern of the heart, the knowledge about velocity and strain rate distribution over the whole ventricle can provide more valuable diagnostic information about motion disorders. For the assessment of intracardiac blood flow three-dimensional color Doppler has already shown its clinical utility. We have developed methods to produce strain rate images by means of 3D tissue Doppler echocardiography. The tissue Doppler and strain rate images can be visualized and quantified by different methods. The methods are integrated into an interactively usable software environment, making them available in clinical everyday life. Our software provides the physician with a valuable tool for diagnosis of heart wall motion.
The PLUNC 3D treatment planning system: a dynamic alternative to commercially available systems.
Tewell, Marshall A; Adams, Robert
2004-01-01
Three-dimensional (3D) treatment planning is an integral step in the treatment of various cancers when radiation is prescribed as either the primary or adjunctive modality, especially when the gross tumor volume lies in a difficult to reach area or is proximal to critical bodily structures. Today, 3D systems have made it possible to more precisely localize tumors in order to treat a higher ratio of cancer cells to normal tissue. Over the past 15 years, these systems have evolved into complex tools that utilize powerful computational algorithms that offer diverse functional capabilities, while simultaneously attempting to maintain a user-friendly quality. A major disadvantage of commercial systems is that users do not have access to the programming source code, resulting in significantly limited clinical and technological flexibility. As an alternative, in-house systems such as Plan-UNC (PLUNC) offer optimal flexibility that is vital to research institutions and important to treatment facilities. Despite this weakness, commercially available systems have become the norm because their commissioning time is significantly less and because many facilities do not have computer experts on-site.
Song, Liang; Kim, Chulhong; Maslov, Konstantin; Shung, K Kirk; Wang, Lihong V
2009-08-01
Noninvasive photoacoustic sentinel lymph node (SLN) mapping with high spatial resolution has the potential to improve the false negative rate and eliminate the use of radioactive tracers in SLN identification. In addition, the demonstrated high spatial resolution may enable physicians to replace SLN biopsy with fine needle aspiration biopsy, and thus reduce the risk of associated morbidity. The primary goal of this study is to demonstrate the feasibility of high-speed 3D photoacoustic imaging of the uptake and clearance dynamics of Evans blue dye in SLNs. The photoacoustic imaging system was developed with a 30 MHz ultrasound array and a kHz repetition rate laser system. It acquires one 3D photoacoustic image of 166 B-scan frames in 1 s, with axial, lateral, and elevational resolutions of 25, 70, and 200 microm, respectively. With optic-fiber based light delivery, the entire system is compact and is convenient to use. Upon injection of Evans blue, a blue dye currently used in clinical SLN biopsy, SLNs in mice and rats were accurately and noninvasively mapped in vivo using our imaging system. In our experiments, the SLNs were found to be located at approximately 0.65 mm below the skin surface in mice and approximately 1.2 mm in rats. In some cases, lymph vessels and lymphatic valves were also imaged. The dye dynamics--accumulation and clearance--in SLNs were quantitatively monitored by sequential 3D imaging with temporal resolution of as high as approximately 6 s. The demonstrated capability suggests that high-speed 3D photoacoustic imaging should facilitate the understanding of the dynamics of various dyes in SLNs and potentially help identify SLNs with high accuracy. PMID:19746805
NASA Technical Reports Server (NTRS)
Koppenhoefer, Kyle C.; Gullerud, Arne S.; Ruggieri, Claudio; Dodds, Robert H., Jr.; Healy, Brian E.
1998-01-01
This report describes theoretical background material and commands necessary to use the WARP3D finite element code. WARP3D is under continuing development as a research code for the solution of very large-scale, 3-D solid models subjected to static and dynamic loads. Specific features in the code oriented toward the investigation of ductile fracture in metals include a robust finite strain formulation, a general J-integral computation facility (with inertia, face loading), an element extinction facility to model crack growth, nonlinear material models including viscoplastic effects, and the Gurson-Tver-gaard dilatant plasticity model for void growth. The nonlinear, dynamic equilibrium equations are solved using an incremental-iterative, implicit formulation with full Newton iterations to eliminate residual nodal forces. The history integration of the nonlinear equations of motion is accomplished with Newmarks Beta method. A central feature of WARP3D involves the use of a linear-preconditioned conjugate gradient (LPCG) solver implemented in an element-by-element format to replace a conventional direct linear equation solver. This software architecture dramatically reduces both the memory requirements and CPU time for very large, nonlinear solid models since formation of the assembled (dynamic) stiffness matrix is avoided. Analyses thus exhibit the numerical stability for large time (load) steps provided by the implicit formulation coupled with the low memory requirements characteristic of an explicit code. In addition to the much lower memory requirements of the LPCG solver, the CPU time required for solution of the linear equations during each Newton iteration is generally one-half or less of the CPU time required for a traditional direct solver. All other computational aspects of the code (element stiffnesses, element strains, stress updating, element internal forces) are implemented in the element-by- element, blocked architecture. This greatly improves
NASA Astrophysics Data System (ADS)
Lahiri, Sivaji; Mamtani, Manish A.
2016-07-01
In this study, orientations of 157 quartz veins occurring in metabasalts of the Gadag region (Dharwar craton, southern India) are used to plot the 3-D Mohr stress circle, which provides information about relative stress/fluid pressure (Pf) conditions, as well as stress state during Pf fluctuation. To scale the 3-D Mohr circle, vein orientation data are integrated with (a) available estimates from fluid inclusions of highest recorded Pf (390 MPa) and lowest recorded Pf (50 MPa) and (b) intrinsic rupture criterion that empirically quantify rock properties. Based on the scaled 3-D Mohr circle, the absolute magnitudes of the three principal stresses are quantified for high and low Pf. Of 157 veins investigated here, 14 veins are identified as having favourable orientation for dilation at high as well as low Pf. These 14 veins have a mean strike of 150°, which is similar to the orientation of the gold-bearing quartz lodes reported in the region. The effective normal stress (σ‧n = σn-Pf) prevalent during dilation of fracture/fabric anisotropy with 150° strike is calculated to be -11.5 MPa at high Pf, and -1.0 MPa at low Pf. Thus, it is interpreted that in the Gadag region, a change in σ‧n of 10.5 MPa prevailed during Pf fluctuation and associated separation of gold from the fluid.
Linear and nonlinear instability and ligament dynamics in 3D laminar two-layer liquid/liquid flows
NASA Astrophysics Data System (ADS)
Ó Náraigh, Lennon; Valluri, Prashant; Scott, David; Bethune, Iain; Spelt, Peter
2013-11-01
We consider the linear and nonlinear stability of two-phase density-matched but viscosity contrasted fluids subject to laminar Poiseuille flow in a channel, paying particular attention to the formation of three-dimensional waves. The Orr-Sommerfeld-Squire analysis is used along with DNS of the 3D two-phase Navier-Stokes equations using our newly launched TPLS Solver (http://edin.ac/10cRKzS). For the parameter regimes considered, we demonstrate the existence of two distinct mechanisms whereby 3D waves enter the system, and dominate at late time. There exists a direct route, whereby 3D waves are amplified by the standard linear mechanism; for certain parameter classes, such waves grow at a rate less than but comparable to that of most-dangerous two-dimensional mode. Additionally, there is a weakly nonlinear route, whereby a purely spanwise wave couples to a streamwise mode and grows exponentially. We demonstrate these mechanisms in isolation and in concert. Consideration is also given to the ultimate state of these waves: persistent three-dimensional nonlinear waves are stretched and distorted by the base flow, thereby producing regimes of ligaments, ``sheets,'' or ``interfacial turbulence.'' HECToR RAP/dCSE Project e174, HPC-Europa 2.
Characterization of 3D filament dynamics in a MAST SOL flux tube geometry
NASA Astrophysics Data System (ADS)
Walkden, N. R.; Dudson, B. D.; Fishpool, G.
2013-10-01
Non-linear simulations of filament propagation in a realistic MAST SOL flux tube geometry using the BOUT++ fluid modelling framework show an isolation of the dynamics of the filament in the divertor region from the midplane region due to three features of the magnetic geometry; the variation of magnetic curvature along the field line, the expansion of the flux tube and strong magnetic shear. Of the three effects, the latter two lead to a midplane ballooning feature of the filament, whilst the former leads to a ballooning around the X-points. In simulations containing all three effects the filament is observed to balloon at the midplane, suggesting that the role of curvature variation is sub-dominant to the flux expansion and magnetic shear. The magnitudes of these effects are all strongest near the X-point which leads to the formation of parallel density gradients. The filaments simulated, which represent filaments in MAST, are identified as resistive ballooning, meaning that their motion is inertially limited, not sheath limited. Parallel density gradients can drive the filament towards a Boltzmann response when the collisionalityof the plasma is low. The results here show that the formation of parallel density gradients is a natural and inevitable consequence of a realistic magnetic geometry and therefore the transition to the Boltzmann response is a consequence of the use of realistic magnetic geometry and does not require initializing specifically varying background profiles as in slab simulations. The filaments studied here are stable to the linear resistive drift-wave instability but are subject to the non-linear effects associated with the Boltzmann response, particularly Boltzmann spinning. The Boltzmann response causes the filament to spin on an axis. In later stages of its evolution a non-linear turbulent state develops where the vorticity evolves into a turbulent eddy field on the same length scale as the parallel current. The transition from interchange
Toma, Milan; Jensen, Morten Ø; Einstein, Daniel R; Yoganathan, Ajit P; Cochran, Richard P; Kunzelman, Karyn S
2016-04-01
Numerical models of native heart valves are being used to study valve biomechanics to aid design and development of repair procedures and replacement devices. These models have evolved from simple two-dimensional approximations to complex three-dimensional, fully coupled fluid-structure interaction (FSI) systems. Such simulations are useful for predicting the mechanical and hemodynamic loading on implanted valve devices. A current challenge for improving the accuracy of these predictions is choosing and implementing modeling boundary conditions. In order to address this challenge, we are utilizing an advanced in vitro system to validate FSI conditions for the mitral valve system. Explanted ovine mitral valves were mounted in an in vitro setup, and structural data for the mitral valve was acquired with [Formula: see text]CT. Experimental data from the in vitro ovine mitral valve system were used to validate the computational model. As the valve closes, the hemodynamic data, high speed leaflet dynamics, and force vectors from the in vitro system were compared to the results of the FSI simulation computational model. The total force of 2.6 N per papillary muscle is matched by the computational model. In vitro and in vivo force measurements enable validating and adjusting material parameters to improve the accuracy of computational models. The simulations can then be used to answer questions that are otherwise not possible to investigate experimentally. This work is important to maximize the validity of computational models of not just the mitral valve, but any biomechanical aspect using computational simulation in designing medical devices.
Toma, Milan; Jensen, Morten Ø; Einstein, Daniel R; Yoganathan, Ajit P; Cochran, Richard P; Kunzelman, Karyn S
2016-04-01
Numerical models of native heart valves are being used to study valve biomechanics to aid design and development of repair procedures and replacement devices. These models have evolved from simple two-dimensional approximations to complex three-dimensional, fully coupled fluid-structure interaction (FSI) systems. Such simulations are useful for predicting the mechanical and hemodynamic loading on implanted valve devices. A current challenge for improving the accuracy of these predictions is choosing and implementing modeling boundary conditions. In order to address this challenge, we are utilizing an advanced in vitro system to validate FSI conditions for the mitral valve system. Explanted ovine mitral valves were mounted in an in vitro setup, and structural data for the mitral valve was acquired with [Formula: see text]CT. Experimental data from the in vitro ovine mitral valve system were used to validate the computational model. As the valve closes, the hemodynamic data, high speed leaflet dynamics, and force vectors from the in vitro system were compared to the results of the FSI simulation computational model. The total force of 2.6 N per papillary muscle is matched by the computational model. In vitro and in vivo force measurements enable validating and adjusting material parameters to improve the accuracy of computational models. The simulations can then be used to answer questions that are otherwise not possible to investigate experimentally. This work is important to maximize the validity of computational models of not just the mitral valve, but any biomechanical aspect using computational simulation in designing medical devices. PMID:26183963
Kumar, Ankur N.; Miga, Michael I.; Pheiffer, Thomas S.; Chambless, Lola B.; Thompson, Reid C.; Dawant, Benoit M.
2014-01-01
One of the major challenges impeding advancement in image-guided surgical (IGS) systems is the soft-tissue deformation during surgical procedures. These deformations reduce the utility of the patient’s preoperative images and may produce inaccuracies in the application of preoperative surgical plans. Solutions to compensate for the tissue deformations include the acquisition of intraoperative tomographic images of the whole organ for direct displacement measurement and techniques that combines intraoperative organ surface measurements with computational biomechanical models to predict subsurface displacements. The later solution has the advantage of being less expensive and amenable to surgical workflow. Several modalities such as textured laser scanners, conoscopic holography, and stereo-pair cameras have been proposed for the intraoperative 3D estimation of organ surfaces to drive patient-specific biomechanical models for the intraoperative update of preoperative images. Though each modality has its respective advantages and disadvantages, stereo-pair camera approaches used within a standard operating microscope is the focus of this article. A new method that permits the automatic and near real-time estimation of 3D surfaces (at 1Hz) under varying magnifications of the operating microscope is proposed. This method has been evaluated on a CAD phantom object and on full-length neurosurgery video sequences (~1 hour) acquired intraoperatively by the proposed stereovision system. To the best of our knowledge, this type of validation study on full-length brain tumor surgery videos has not been done before. The method for estimating the unknown magnification factor of the operating microscope achieves accuracy within 0.02 of the theoretical value on a CAD phantom and within 0.06 on 4 clinical videos of the entire brain tumor surgery. When compared to a laser range scanner, the proposed method for reconstructing 3D surfaces intraoperatively achieves root mean square
Faster Aerodynamic Simulation With Cart3D
NASA Technical Reports Server (NTRS)
2003-01-01
A NASA-developed aerodynamic simulation tool is ensuring the safety of future space operations while providing designers and engineers with an automated, highly accurate computer simulation suite. Cart3D, co-winner of NASA's 2002 Software of the Year award, is the result of over 10 years of research and software development conducted by Michael Aftosmis and Dr. John Melton of Ames Research Center and Professor Marsha Berger of the Courant Institute at New York University. Cart3D offers a revolutionary approach to computational fluid dynamics (CFD), the computer simulation of how fluids and gases flow around an object of a particular design. By fusing technological advancements in diverse fields such as mineralogy, computer graphics, computational geometry, and fluid dynamics, the software provides a new industrial geometry processing and fluid analysis capability with unsurpassed automation and efficiency.
Fully 3D Multiple Beam Dynamics Processes Simulation for the Fermilab Tevatron
Stern, E.; Amundson, J.; Spentzouris, P; Valishev, A.; /Fermilab
2010-06-01
The Fermilab Tevatron has been, until 2010, the premier high-energy physics collider in the world. The data collected over the last decade by high-energy physics experiments running at the Tevatron have been analyzed to make important measurements in fundamental areas such as B meson masses and flavor oscillation, searches for the Higgs boson, and supersymmetry. Collecting these data at the limits of detectability has required the Tevatron to operate reliably at high beam intensities to maximize the number of collisions to analyze. This impressive achievement has been assisted by the use of HPC resources and software provided through the SciDAC program. This paper describes the enhancements to the BeamBeam3d code to realistically simulate the Tevatron, the validation of these simulations, and the improvement in equipment reliability and personal safety achieved with the aid of simulations.
NASA Astrophysics Data System (ADS)
Daria, Vincent R.; Stricker, Christian; Bekkers, John; Redman, Steve; Bachor, Hans
2010-08-01
We demonstrate a multi-functional system capable of multiple-site two-photon excitation of photo-sensitive compounds as well as transfer of optical mechanical properties on an array of mesoscopic particles. We use holographic projection of a single Ti:Sapphire laser operating in femtosecond pulse mode to show that the projected three-dimensional light patterns have sufficient spatiotemporal photon density for multi-site two-photon excitation of biological fluorescent markers and caged neurotransmitters. Using the same laser operating in continuous-wave mode, we can use the same light patterns for non-invasive transfer of both linear and orbital angular momentum on a variety of mesoscopic particles. The system also incorporates high-speed scanning using acousto-optic modulators to rapidly render 3D images of neuron samples via two-photon microscopy.
Tidal dynamics of the Terminos Lagoon, Mexico: observations and 3D numerical modelling
NASA Astrophysics Data System (ADS)
Contreras Ruiz Esparza, Adolfo; Douillet, Pascal; Zavala-Hidalgo, Jorge
2014-09-01
The tidal circulation patterns in the Terminos Lagoon were studied based on the analysis of 1 year of measurements and numerical simulations using a baroclinic 3D hydrodynamic model, the MARS3D. A gauging network was installed consisting of six self-recording pressure-temperature sensors, a tide gauge station and two current profilers, with pressure and temperature sensors moored in the main lagoon inlets. Model simulations were validated against current and sea level observations and were used to analyse the circulation patterns caused by the tidal forcing. The numerical model was forced with eight harmonic components, four diurnal ( K 1, O 1, P 1, Q 1) and four semi-diurnal ( M 2, S 2, N 2, K 2), extracted from the TPX0.7 database. The tidal patterns in the study area vary from mixed, mainly diurnal in the two main inlets of the lagoon, to diurnal in its interior. The tidal residual circulation inside the lagoon is dominated by a cyclonic gyre. The results indicate a net flux from the southwest Ciudad del Carmen inlet (CdC) towards the northeast Puerto Real inlet (PtR) along the southern side of the lagoon and the opposite in the northern side. The results indicate two areas of strong currents in the vicinity of the inlets and weak currents inside the lagoon. The area of strong currents in the vicinity of the CdC inlet is larger than that observed in the PtR inlet. Nevertheless, the current analysis indicates that the highest current speeds, which can reach a magnitude of 1.9 m s-1, occurred in PtR. A further analysis of the tide distortion in the inlets revealed that both passages are ebb dominated.
NASA Astrophysics Data System (ADS)
Guasto, Jeffrey; Schmidt, Brian; Lawrence, Michael; Breuer, Kenneth
2007-11-01
Three-dimensional total internal reflection velocimetry (3D-TIRV) is used to measure the trajectories of fluorescent tracer particles within 200 nm of a wall. Diffusion and shear-induced motion can result in mean velocity measurement errors, and by taking measurements using different particle sizes and sampling times, we quantify these effects and compare with theory. We also use 3D-TIRV to observe and characterize the adhesion, surface rolling and release dynamics of particles that can adhere to the surface through the action of biological binding proteins. Particles coated with P-Selectin are allowed to adhere to and detach from a PSGL-1-coated microchannel surface, modeling the interaction between leukocytes (white blood cells) and blood vessels, respectively. Binding affinities, bond strengths and hydrodynamic interactions are inferred from the trajectory data.
Visualization of Unsteady Computational Fluid Dynamics
NASA Technical Reports Server (NTRS)
Haimes, Robert
1997-01-01
The current compute environment that most researchers are using for the calculation of 3D unsteady Computational Fluid Dynamic (CFD) results is a super-computer class machine. The Massively Parallel Processors (MPP's) such as the 160 node IBM SP2 at NAS and clusters of workstations acting as a single MPP (like NAS's SGI Power-Challenge array and the J90 cluster) provide the required computation bandwidth for CFD calculations of transient problems. If we follow the traditional computational analysis steps for CFD (and we wish to construct an interactive visualizer) we need to be aware of the following: (1) Disk space requirements. A single snap-shot must contain at least the values (primitive variables) stored at the appropriate locations within the mesh. For most simple 3D Euler solvers that means 5 floating point words. Navier-Stokes solutions with turbulence models may contain 7 state-variables. (2) Disk speed vs. Computational speeds. The time required to read the complete solution of a saved time frame from disk is now longer than the compute time for a set number of iterations from an explicit solver. Depending, on the hardware and solver an iteration of an implicit code may also take less time than reading the solution from disk. If one examines the performance improvements in the last decade or two, it is easy to see that depending on disk performance (vs. CPU improvement) may not be the best method for enhancing interactivity. (3) Cluster and Parallel Machine I/O problems. Disk access time is much worse within current parallel machines and cluster of workstations that are acting in concert to solve a single problem. In this case we are not trying to read the volume of data, but are running the solver and the solver outputs the solution. These traditional network interfaces must be used for the file system. (4) Numerics of particle traces. Most visualization tools can work upon a single snap shot of the data but some visualization tools for transient
Continuing Validation of Computational Fluid Dynamics for Supersonic Retropropulsion
NASA Technical Reports Server (NTRS)
Schauerhamer, Daniel Guy; Trumble, Kerry A.; Kleb, Bil; Carlson, Jan-Renee; Edquist, Karl T.
2011-01-01
A large step in the validation of Computational Fluid Dynamics (CFD) for Supersonic Retropropulsion (SRP) is shown through the comparison of three Navier-Stokes solvers (DPLR, FUN3D, and OVERFLOW) and wind tunnel test results. The test was designed specifically for CFD validation and was conducted in the Langley supersonic 4 x4 Unitary Plan Wind Tunnel and includes variations in the number of nozzles, Mach and Reynolds numbers, thrust coefficient, and angles of orientation. Code-to-code and code-to-test comparisons are encouraging and possible error sources are discussed.
Numerical, analytical, experimental study of fluid dynamic forces in seals
NASA Astrophysics Data System (ADS)
Shapiro, William; Artiles, Antonio; Aggarwal, Bharat; Walowit, Jed; Athavale, Mahesh M.; Preskwas, Andrzej J.
1992-04-01
NASA/Lewis Research Center is sponsoring a program for providing computer codes for analyzing and designing turbomachinery seals for future aerospace and engine systems. The program is made up of three principal components: (1) the development of advanced three dimensional (3-D) computational fluid dynamics codes, (2) the production of simpler two dimensional (2-D) industrial codes, and (3) the development of a knowledge based system (KBS) that contains an expert system to assist in seal selection and design. The first task has been to concentrate on cylindrical geometries with straight, tapered, and stepped bores. Improvements have been made by adoption of a colocated grid formulation, incorporation of higher order, time accurate schemes for transient analysis and high order discretization schemes for spatial derivatives. This report describes the mathematical formulations and presents a variety of 2-D results, including labyrinth and brush seal flows. Extensions of 3-D are presently in progress.
Numerical, analytical, experimental study of fluid dynamic forces in seals
NASA Technical Reports Server (NTRS)
Shapiro, William; Artiles, Antonio; Aggarwal, Bharat; Walowit, Jed; Athavale, Mahesh M.; Preskwas, Andrzej J.
1992-01-01
NASA/Lewis Research Center is sponsoring a program for providing computer codes for analyzing and designing turbomachinery seals for future aerospace and engine systems. The program is made up of three principal components: (1) the development of advanced three dimensional (3-D) computational fluid dynamics codes, (2) the production of simpler two dimensional (2-D) industrial codes, and (3) the development of a knowledge based system (KBS) that contains an expert system to assist in seal selection and design. The first task has been to concentrate on cylindrical geometries with straight, tapered, and stepped bores. Improvements have been made by adoption of a colocated grid formulation, incorporation of higher order, time accurate schemes for transient analysis and high order discretization schemes for spatial derivatives. This report describes the mathematical formulations and presents a variety of 2-D results, including labyrinth and brush seal flows. Extensions of 3-D are presently in progress.
Integrating Dynamic Data and Sensors with Semantic 3D City Models in the Context of Smart Cities
NASA Astrophysics Data System (ADS)
Chaturvedi, K.; Kolbe, T. H.
2016-10-01
Smart cities provide effective integration of human, physical and digital systems operating in the built environment. The advancements in city and landscape models, sensor web technologies, and simulation methods play a significant role in city analyses and improving quality of life of citizens and governance of cities. Semantic 3D city models can provide substantial benefits and can become a central information backbone for smart city infrastructures. However, current generation semantic 3D city models are static in nature and do not support dynamic properties and sensor observations. In this paper, we propose a new concept called Dynamizer allowing to represent highly dynamic data and providing a method for injecting dynamic variations of city object properties into the static representation. The approach also provides direct capability to model complex patterns based on statistics and general rules and also, real-time sensor observations. The concept is implemented as an Application Domain Extension for the CityGML standard. However, it could also be applied to other GML-based application schemas including the European INSPIRE data themes and national standards for topography and cadasters like the British Ordnance Survey Mastermap or the German cadaster standard ALKIS.
A 3-D adaptive mesh refinement algorithm for multimaterial gas dynamics
Puckett, E.G. ); Saltzman, J.S. )
1991-08-12
Adaptive Mesh Refinement (AMR) in conjunction with high order upwind finite difference methods has been used effectively on a variety of problems. In this paper we discuss an implementation of an AMR finite difference method that solves the equations of gas dynamics with two material species in three dimensions. An equation for the evolution of volume fractions augments the gas dynamics system. The material interface is preserved and tracked from the volume fractions using a piecewise linear reconstruction technique. 14 refs., 4 figs.
Dynamical system of scalar field from 2-dimension to 3-D and its cosmological implications
NASA Astrophysics Data System (ADS)
Fang, Wei; Tu, Hong; Huang, Jiasheng; Shu, Chenggang
2016-09-01
We give the three-dimensional dynamical autonomous systems for most of the popular scalar field dark energy models including (phantom) quintessence, (phantom) tachyon, K-essence, and general non-canonical scalar field models, change the dynamical variables from variables (x, y, λ ) to observable related variables (w_{φ }, Ω _{φ }, λ ), and show the intimate relationships between those scalar fields that the three-dimensional system of K-essence can reduce to (phantom) tachyon, general non-canonical scalar field can reduce to (phantom) quintessence and K-essence can also reduce to (phantom) quintessence for some special cases. For the applications of the three-dimensional dynamical systems, we investigate several special cases and give the exactly dynamical solutions in detail. In the end of this paper, we argue that it is more convenient and also has more physical meaning to express the differential equations of dynamical systems in (w_{φ }, Ω _{φ }, λ ) instead of variables (x, y, λ ) and to investigate the dynamical system in three dimensions instead of two dimensions. We also raise a question about the possibility of the chaotic behavior in the spatially flat single scalar field FRW cosmological models in the presence of ordinary matter.
Dynamic 2D ultrasound and 3D CT image registration of the beating heart.
Huang, Xishi; Moore, John; Guiraudon, Gerard; Jones, Douglas L; Bainbridge, Daniel; Ren, Jing; Peters, Terry M
2009-08-01
Two-dimensional ultrasound (US) is widely used in minimally invasive cardiac procedures due to its convenience of use and noninvasive nature. However, the low quality of US images often limits their utility as a means for guiding procedures, since it is often difficult to relate the images to their anatomical context. To improve the interpretability of the US images while maintaining US as a flexible anatomical and functional real-time imaging modality, we describe a multimodality image navigation system that integrates 2D US images with their 3D context by registering them to high quality preoperative models based on magnetic resonance imaging (MRI) or computed tomography (CT) images. The mapping from such a model to the patient is completed using spatial and temporal registrations. Spatial registration is performed by a two-step rapid registration method that first approximately aligns the two images as a starting point to an automatic registration procedure. Temporal alignment is performed with the aid of electrocardiograph (ECG) signals and a latency compensation method. Registration accuracy is measured by calculating the TRE. Results show that the error between the US and preoperative images of a beating heart phantom is 1.7 +/-0.4 mm, with a similar performance being observed in in vivo animal experiments.
Naito, Kozo; Takagi, Hiroyasu; Yamada, Norimasa; Hashimoto, Shinichi; Maruyama, Takeo
2014-12-01
The shoulder internal rotation (IR) and forearm pronation (PR) are important elements for baseball pitching, however, how rapid rotations of IR and PR are produced by muscular torques and inter-segmental forces is not clear. The aim of this study is to clarify how IR and PR angular velocities are maximized, depending on muscular torque and interactive torque effects, and gain a detailed knowledge about inter-segmental interaction within a multi-joint linked chain. The throwing movements of eight collegiate baseball pitchers were recorded by a motion capture system, and induced-acceleration analysis was used to assess the respective contributions of the muscular (MUS) and interactive torques associated with gyroscopic moment (GYR), and Coriolis (COR) and centrifugal forces (CEN) to maximum angular velocities of IR (MIRV) and PR (MPRV). The results showed that the contribution of MUS account for 98.0% of MIRV, while that contribution to MPRV was indicated as negative (-48.1%). It was shown that MPRV depends primarily on the interactive torques associated with GYR and CEN, but the effects of GYR, COR and CEN on MIRV are negligible. In conclusion, rapid PR motion during pitching is created by passive-effect, and is likely a natural movement which arises from 3D throwing movement. Applying the current analysis to IR and PR motions is helpful in providing the implications for improving performance and considering conditioning methods for pitchers.
Naito, Kozo; Takagi, Hiroyasu; Yamada, Norimasa; Hashimoto, Shinichi; Maruyama, Takeo
2014-12-01
The shoulder internal rotation (IR) and forearm pronation (PR) are important elements for baseball pitching, however, how rapid rotations of IR and PR are produced by muscular torques and inter-segmental forces is not clear. The aim of this study is to clarify how IR and PR angular velocities are maximized, depending on muscular torque and interactive torque effects, and gain a detailed knowledge about inter-segmental interaction within a multi-joint linked chain. The throwing movements of eight collegiate baseball pitchers were recorded by a motion capture system, and induced-acceleration analysis was used to assess the respective contributions of the muscular (MUS) and interactive torques associated with gyroscopic moment (GYR), and Coriolis (COR) and centrifugal forces (CEN) to maximum angular velocities of IR (MIRV) and PR (MPRV). The results showed that the contribution of MUS account for 98.0% of MIRV, while that contribution to MPRV was indicated as negative (-48.1%). It was shown that MPRV depends primarily on the interactive torques associated with GYR and CEN, but the effects of GYR, COR and CEN on MIRV are negligible. In conclusion, rapid PR motion during pitching is created by passive-effect, and is likely a natural movement which arises from 3D throwing movement. Applying the current analysis to IR and PR motions is helpful in providing the implications for improving performance and considering conditioning methods for pitchers. PMID:25303496
Dynamic 3-D chemical agent cloud mapping using a sensor constellation deployed on mobile platforms
NASA Astrophysics Data System (ADS)
Cosofret, Bogdan R.; Konno, Daisei; Rossi, David; Marinelli, William J.; Seem, Pete
2014-05-01
The need for standoff detection technology to provide early Chem-Bio (CB) threat warning is well documented. Much of the information obtained by a single passive sensor is limited to bearing and angular extent of the threat cloud. In order to obtain absolute geo-location, range to threat, 3-D extent and detailed composition of the chemical threat, fusion of information from multiple passive sensors is needed. A capability that provides on-the-move chemical cloud characterization is key to the development of real-time Battlespace Awareness. We have developed, implemented and tested algorithms and hardware to perform the fusion of information obtained from two mobile LWIR passive hyperspectral sensors. The implementation of the capability is driven by current Nuclear, Biological and Chemical Reconnaissance Vehicle operational tactics and represents a mission focused alternative of the already demonstrated 5-sensor static Range Test Validation System (RTVS).1 The new capability consists of hardware for sensor pointing and attitude information which is made available for streaming and aggregation as part of the data fusion process for threat characterization. Cloud information is generated using 2-sensor data ingested into a suite of triangulation and tomographic reconstruction algorithms. The approaches are amenable to using a limited number of viewing projections and unfavorable sensor geometries resulting from mobile operation. In this paper we describe the system architecture and present an analysis of results obtained during the initial testing of the system at Dugway Proving Ground during BioWeek 2013.
Ultrasensitive detection of 3D cerebral microvascular network dynamics in vivo
Pan, Yingtian; You, Jiang; Volkow, Nora D.; Park, Ki; Du, Congwu
2014-01-01
Despite widespread applications of multiphoton microscopy in microcirculation, its small field of view and inability to instantaneously quantify cerebral blood flow velocity (CBFv) in vascular networks limit its utility in investigating the heterogeneous responses to brain stimulations. Optical Doppler tomography (ODT) provides 3D images of CBFv networks, but it suffers poor sensitivity for measuring capillary flows. Here we report a new method, contrast-enhanced ODT with intralipid that significantly improves quantitative CBFv imaging of capillary networks by obviating the errors from long latency between flowing red blood cells (low hematocrit ~20% in capillaries). This enhanced sensitivity allowed us to measure the ultraslow microcirculation surrounding a brain tumor and the abnormal ingrowth of capillary flows in the tumor as well as in ischemia triggered by chronic cocaine in the mouse brain that could not be detected by regular ODT. It also enabled significantly enhanced sensitivity for quantifying the heterogeneous CBFv responses of vascular networks to acute cocaine. Inasmuch as intralipids are widely used for parenteral nutrition the intralipid contrast method has translational potential for clinical applications. PMID:25192654
Quantitative 3D analysis of shape dynamics of the left ventricle
NASA Astrophysics Data System (ADS)
Scowen, Barry C.; Smith, Stephen L.; Vannan, Mani A.; Arsenault, Marie
1998-07-01
There is an established link between Left Ventricular (LV) geometry and its performance. As a consequence of ischemic heart disease and the attempt to relieve myocardial tissue stress, ventricle shape begins to distort from a conical to spherical geometry with a reduction in pumping efficiency of the chamber. If untreated, premature heart failure will result. To increase the changes of successful treatment it is obviously important for the benefit of the patient to detect these abnormalities as soon as possible. It is the development of a technique to characterize and quantify the shape of the left ventricle that is described here. The system described in this paper uses a novel helix model which combines the advantages of current two dimensional (2D) quantitative measures which provide limited information, with 3D qualitative methods which provide accurate reconstructions of the LV using computationally expensive rendering schemes. A phantom object and dog ventricle (normal/abnormal) were imaged and helical models constructed. The result are encouraging with differences between normal and abnormal ventricles in both diastole and systole able to be determined. Further work entails building a library of subjects in order to determine the relationship between ventricle geometry and quantitative measurements.
Cation Exchange in Dynamic 3D Porous Magnets: Improvement of the Physical Properties.
Grancha, Thais; Acosta, Alvaro; Cano, Joan; Ferrando-Soria, Jesús; Seoane, Beatriz; Gascon, Jorge; Pasán, Jorge; Armentano, Donatella; Pardo, Emilio
2015-11-16
We report two novel three-dimensional porous coordination polymers (PCPs) of formulas Li4{Mn4[Cu2(Me3mpba)2]3}·68H2O (2) and K4{Mn4[Cu2(Me3mpba)2]3}·69H2O (3) obtained-via alkali cation exchange in a single-crystal to single-crystal process-from the earlier reported anionic manganese(II)-copper(II) PCP of formula Na4{Mn4[Cu2(Me3mpba)2]3}·60H2O (1) [Me3mpba(4-) = N,N'-2,4,6-trimethyl-1,3-phenylenebis(oxamate)]. This postsynthetic process succeeds where the direct synthesis in solution from the corresponding building blocks fails and affords significantly more robust PCPs with enhanced magnetic properties [long-range 3D magnetic ordering temperatures for the dehydrated phases (1'-3') of 2.0 (1'), 12.0 (2'), and 20.0 K (3')]. Changes in the adsorptive properties upon postsynthetic exchange suggest that the nature, electrostatic properties, mobility, and location of the cations within the framework are crucial for the enhanced structural stability. Overall, these results further confirm the potential of postsynthetic methods (including cation exchange) to obtain PCPs with novel or enhanced physical properties while maintaining unaltered their open-framework structures. PMID:26492551
The 1999 Izmit, Turkey, earthquake: A 3D dynamic stress transfer model of intraearthquake triggering
Harris, R.A.; Dolan, J.F.; Hartleb, R.; Day, S.M.
2002-01-01
Before the August 1999 Izmit (Kocaeli), Turkey, earthquake, theoretical studies of earthquake ruptures and geological observations had provided estimates of how far an earthquake might jump to get to a neighboring fault. Both numerical simulations and geological observations suggested that 5 km might be the upper limit if there were no transfer faults. The Izmit earthquake appears to have followed these expectations. It did not jump across any step-over wider than 5 km and was instead stopped by a narrower step-over at its eastern end and possibly by a stress shadow caused by a historic large earthquake at its western end. Our 3D spontaneous rupture simulations of the 1999 Izmit earthquake provide two new insights: (1) the west- to east-striking fault segments of this part of the North Anatolian fault are oriented so as to be low-stress faults and (2) the easternmost segment involved in the August 1999 rupture may be dipping. An interesting feature of the Izmit earthquake is that a 5-km-long gap in surface rupture and an adjacent 25° restraining bend in the fault zone did not stop the earthquake. The latter observation is a warning that significant fault bends in strike-slip faults may not arrest future earthquakes.
Cation Exchange in Dynamic 3D Porous Magnets: Improvement of the Physical Properties.
Grancha, Thais; Acosta, Alvaro; Cano, Joan; Ferrando-Soria, Jesús; Seoane, Beatriz; Gascon, Jorge; Pasán, Jorge; Armentano, Donatella; Pardo, Emilio
2015-11-16
We report two novel three-dimensional porous coordination polymers (PCPs) of formulas Li4{Mn4[Cu2(Me3mpba)2]3}·68H2O (2) and K4{Mn4[Cu2(Me3mpba)2]3}·69H2O (3) obtained-via alkali cation exchange in a single-crystal to single-crystal process-from the earlier reported anionic manganese(II)-copper(II) PCP of formula Na4{Mn4[Cu2(Me3mpba)2]3}·60H2O (1) [Me3mpba(4-) = N,N'-2,4,6-trimethyl-1,3-phenylenebis(oxamate)]. This postsynthetic process succeeds where the direct synthesis in solution from the corresponding building blocks fails and affords significantly more robust PCPs with enhanced magnetic properties [long-range 3D magnetic ordering temperatures for the dehydrated phases (1'-3') of 2.0 (1'), 12.0 (2'), and 20.0 K (3')]. Changes in the adsorptive properties upon postsynthetic exchange suggest that the nature, electrostatic properties, mobility, and location of the cations within the framework are crucial for the enhanced structural stability. Overall, these results further confirm the potential of postsynthetic methods (including cation exchange) to obtain PCPs with novel or enhanced physical properties while maintaining unaltered their open-framework structures.
Fluid dynamics computer programs for NERVA turbopump
NASA Technical Reports Server (NTRS)
Brunner, J. J.
1972-01-01
During the design of the NERVA turbopump, numerous computer programs were developed for the analyses of fluid dynamic problems within the machine. Program descriptions, example cases, users instructions, and listings for the majority of these programs are presented.
Dong, Xiaoqing; Fang, Yiliang; Wang, Kejing; Zhu, Lijuan; Wang, Ke; Huang, Tao
2016-01-01
With the development of new technologies in transcriptome and epigenetics, RNAs have been identified to play more and more important roles in life processes. Consequently, various methods have been proposed to assess the biological functions of RNAs and thus classify them functionally, among which comparative study of RNA structures is perhaps the most important one. To measure the structural similarity of RNAs and classify them, we propose a novel three dimensional (3D) graphical representation of RNA secondary structure, in which an RNA secondary structure is first transformed into a characteristic sequence based on chemical property of nucleic acids; a dynamic 3D graph is then constructed for the characteristic sequence; and lastly a numerical characterization of the 3D graph is used to represent the RNA secondary structure. We tested our algorithm on three datasets: (1) Dataset I consisting of nine RNA secondary structures of viruses, (2) Dataset II consisting of complex RNA secondary structures including pseudo-knots, and (3) Dataset III consisting of 18 non-coding RNA families. We also compare our method with other nine existing methods using Dataset II and III. The results demonstrate that our method is better than other methods in similarity measurement and classification of RNA secondary structures. PMID:27213271
Sofronov, I.D.; Voronin, B.L.; Butnev, O.I.
1997-12-31
The aim of the work performed is to develop a 3D parallel program for numerical calculation of gas dynamics problem with heat conductivity on distributed memory computational systems (CS), satisfying the condition of numerical result independence from the number of processors involved. Two basically different approaches to the structure of massive parallel computations have been developed. The first approach uses the 3D data matrix decomposition reconstructed at temporal cycle and is a development of parallelization algorithms for multiprocessor CS with shareable memory. The second approach is based on using a 3D data matrix decomposition not reconstructed during a temporal cycle. The program was developed on 8-processor CS MP-3 made in VNIIEF and was adapted to a massive parallel CS Meiko-2 in LLNL by joint efforts of VNIIEF and LLNL staffs. A large number of numerical experiments has been carried out with different number of processors up to 256 and the efficiency of parallelization has been evaluated in dependence on processor number and their parameters.
Wang, Lichun; Cardenas, M Bayani
2015-08-01
The quantitative study of transport through fractured media has continued for many decades, but has often been constrained by observational and computational challenges. Here, we developed an efficient quasi-3D random walk particle tracking (RWPT) algorithm to simulate solute transport through natural fractures based on a 2D flow field generated from the modified local cubic law (MLCL). As a reference, we also modeled the actual breakthrough curves (BTCs) through direct simulations with the 3D advection-diffusion equation (ADE) and Navier-Stokes equations. The RWPT algorithm along with the MLCL accurately reproduced the actual BTCs calculated with the 3D ADE. The BTCs exhibited non-Fickian behavior, including early arrival and long tails. Using the spatial information of particle trajectories, we further analyzed the dynamic dispersion process through moment analysis. From this, asymptotic time scales were determined for solute dispersion to distinguish non-Fickian from Fickian regimes. This analysis illustrates the advantage and benefit of using an efficient combination of flow modeling and RWPT. PMID:26042625
Dynamic tracking of a deformable tissue based on 3D-2D MR-US image registration
NASA Astrophysics Data System (ADS)
Marami, Bahram; Sirouspour, Shahin; Fenster, Aaron; Capson, David W.
2014-03-01
Real-time registration of pre-operative magnetic resonance (MR) or computed tomography (CT) images with intra-operative Ultrasound (US) images can be a valuable tool in image-guided therapies and interventions. This paper presents an automatic method for dynamically tracking the deformation of a soft tissue based on registering pre-operative three-dimensional (3D) MR images to intra-operative two-dimensional (2D) US images. The registration algorithm is based on concepts in state estimation where a dynamic finite element (FE)- based linear elastic deformation model correlates the imaging data in the spatial and temporal domains. A Kalman-like filtering process estimates the unknown deformation states of the soft tissue using the deformation model and a measure of error between the predicted and the observed intra-operative imaging data. The error is computed based on an intensity-based distance metric, namely, modality independent neighborhood descriptor (MIND), and no segmentation or feature extraction from images is required. The performance of the proposed method is evaluated by dynamically deforming 3D pre-operative MR images of a breast phantom tissue based on real-time 2D images obtained from an US probe. Experimental results on different registration scenarios showed that deformation tracking converges in a few iterations. The average target registration error on the plane of 2D US images for manually selected fiducial points was between 0.3 and 1.5 mm depending on the size of deformation.
NASA Astrophysics Data System (ADS)
Guda, Venkata Subba Sai Satish
There have been several advancements in the aerospace industry in areas of design such as aerodynamics, designs, controls and propulsion; all aimed at one common goal i.e. increasing efficiency --range and scope of operation with lesser fuel consumption. Several methods of flow control have been tried. Some were successful, some failed and many were termed as impractical. The low Reynolds number regime of 104 - 105 is a very interesting range. Flow physics in this range are quite different than those of higher Reynolds number range. Mid and high altitude UAV's, MAV's, sailplanes, jet engine fan blades, inboard helicopter rotor blades and wind turbine rotors are some of the aerodynamic applications that fall in this range. The current study deals with using dynamic roughness as a means of flow control over a NACA 0012 airfoil at low Reynolds numbers. Dynamic 3-D surface roughness elements on an airfoil placed near the leading edge aim at increasing the efficiency by suppressing the effects of leading edge separation like leading edge stall by delaying or totally eliminating flow separation. A numerical study of the above method has been carried out by means of a Large Eddy Simulation, a mathematical model for turbulence in Computational Fluid Dynamics, owing to the highly unsteady nature of the flow. A user defined function has been developed for the 3-D dynamic roughness element motion. Results from simulations have been compared to those from experimental PIV data. Large eddy simulations have relatively well captured the leading edge stall. For the clean cases, i.e. with the DR not actuated, the LES was able to reproduce experimental results in a reasonable fashion. However DR simulation results show that it fails to reattach the flow and suppress flow separation compared to experiments. Several novel techniques of grid design and hump creation are introduced through this study.
3D Dynamics of Oblique Rift Systems: Fault Evolution from Rift to Break-up
NASA Astrophysics Data System (ADS)
Brune, S.
2014-12-01
Rift evolution and passive margin formation has been thoroughly investigated using conceptual and numerical models in two dimensions. However, the 2D assumption that the extension direction is perpendicular to the rift trend is often invalid. In fact, the majority of rift systems that lead to continental break-up during the last 150 My involved moderate to high rift obliquity. Yet, the degree to which oblique lithospheric extension affects first-order rift and passive margin properties like surface stress pattern, fault azimuths, and basin geometry, is still not entirely clear. This contribution provides insight in crustal stress patterns and fault orientations by applying a 3D numerical rift model to oblique extensional settings. The presented forward experiments cover the whole spectrum of oblique extension (i.e. rift-orthogonal extension, low obliquity, high obliquity, strike-slip deformation) from initial deformation to breakup. They are conducted using an elasto-visco-plastic finite element model and involve crustal and mantle layers accounting for self-consistent necking of the lithosphere. Even though the model setup is very simple (horizontally layered, no inherited faults), its evolution exhibits a variety of fault orientations that are solely caused by the interaction of far-field stresses with rift-intrinsic buoyancy and strength. Depending on rift obliquity, these orientations involve rift-parallel, extension-orthogonal, and intermediate normal fault directions as well as strike-slip faults. Allowing new insights on fault patterns of the proximal and distal margins, the model shows that individual fault populations are activated in a characteristic multi-phase evolution driven by lateral density variations of the evolving rift system. Model results are in very good agreement with inferences from the well-studied Gulf of Aden and provide testable predictions for other rifts and passive margins worldwide.
3D Case Studies of Monitoring Dynamic Structural Tests using Long Exposure Imagery
NASA Astrophysics Data System (ADS)
McCarthy, D. M. J.; Chandler, J. H.; Palmeri, A.
2014-06-01
Structural health monitoring uses non-destructive testing programmes to detect long-term degradation phenomena in civil engineering structures. Structural testing may also be carried out to assess a structure's integrity following a potentially damaging event. Such investigations are increasingly carried out with vibration techniques, in which the structural response to artificial or natural excitations is recorded and analysed from a number of monitoring locations. Photogrammetry is of particular interest here since a very high number of monitoring locations can be measured using just a few images. To achieve the necessary imaging frequency to capture the vibration, it has been necessary to reduce the image resolution at the cost of spatial measurement accuracy. Even specialist sensors are limited by a compromise between sensor resolution and imaging frequency. To alleviate this compromise, a different approach has been developed and is described in this paper. Instead of using high-speed imaging to capture the instantaneous position at each epoch, long-exposure images are instead used, in which the localised image of the object becomes blurred. The approach has been extended to create 3D displacement vectors for each target point via multiple camera locations, which allows the simultaneous detection of transverse and torsional mode shapes. The proposed approach is frequency invariant allowing monitoring of higher modal frequencies irrespective of a sampling frequency. Since there is no requirement for imaging frequency, a higher image resolution is possible for the most accurate spatial measurement. The results of a small scale laboratory test using off-the-shelf consumer cameras are demonstrated. A larger experiment also demonstrates the scalability of the approach.
NASA Technical Reports Server (NTRS)
Madura, T. I.; Gull, T. R.; Owocki, S. P.; Groh, J. H.; Okazaki, A. T.; Russell, C. M. P.
2011-01-01
We present a three-dimensional (3-D) dynamical model for the broad [Fe III] emission observed in Eta Carinae using the Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS). This model is based on full 3-D Smoothed Particle Hydrodynamics (SPH) simulations of Eta Car's binary colliding winds. Radiative transfer codes are used to generate synthetic spectro-images of [Fe III] emission line structures at various observed orbital phases and STIS slit position angles (PAs). Through a parameter study that varies the orbital inclination i, the PA(theta) that the orbital plane projection of the line-of-sight makes with the apastron side of the semi-major axis, and the PA on the sky of the orbital axis, we are able, for the first time, to tightly constrain the absolute 3-D orientation of the binary orbit. To simultaneously reproduce the blue-shifted emission arcs observed at orbital phase 0.976, STIS slit PA = +38deg, and the temporal variations in emission seen at negative slit PAs, the binary needs to have an i approx. = 130deg to 145deg, Theta approx. = -15deg to +30deg, and an orbital axis projected on the sky at a P A approx. = 302deg to 327deg east of north. This represents a system with an orbital axis that is closely aligned with the inferred polar axis of the Homunculus nebula, in 3-D. The companion star, Eta(sub B), thus orbits clockwise on the sky and is on the observer's side of the system at apastron. This orientation has important implications for theories for the formation of the Homunculus and helps lay the groundwork for orbital modeling to determine the stellar masses.
3D shoulder kinematics for static vs dynamic and passive vs active testing conditions.
Robert-Lachaine, Xavier; Allard, Paul; Godbout, Véronique; Begon, Mickael
2015-09-18
Shoulder motion analysis provides clinicians with references of normal joint rotations. Shoulder joints orientations assessment is often based on series of static positions, while clinicians perform either passive or active tests and exercises mostly in dynamic. These conditions of motion could modify joint coordination and lead to discrepancies with the established references. Hence, the objective was to evaluate the influence of static vs dynamic and passive vs active testing conditions on shoulder joints orientations. Twenty asymptomatic subjects setup with 45 markers on the upper limb and trunk were tracked by an optoelectronic system. Static positions (30°, 60°, 90° and 120° of thoracohumeral elevation) and dynamic motion both in active condition and passively mobilised by an examiner were executed. Three-dimensional sternoclavicular, acromioclavicular, scapulothoracic and glenohumeral joint angles (12 in total) representing the distal segment orientation relative to the proximal segment orientation were estimated using a shoulder kinematical chain model. Separate four-way repeated measures ANOVA were applied on the 12 joint angles with factors of static vs dynamic, passive vs active, thoracohumeral elevation angle (30°, 60°, 90° and 120°) and plane of elevation (frontal and sagittal). Scapulothoracic lateral rotation progressed more during arm elevation in static than in dynamic gaining 4.2° more, and also in passive than in active by 6.6°. Glenohumeral elevation increased more during arm elevation in active than in passive by 4.4°. Shoulder joints orientations are affected by the testing conditions, which should be taken into consideration for data acquisition, inter-study comparison or clinical applications.
3-D numerical investigation of the mantle dynamics associated with the breakup of Pangea
Baumgardner, J.R.
1992-01-01
Three-dimensional finite element calculations in spherical geometry are performed to study the response of the mantle with platelike blocks at its surface to an initial condition corresponding to subduction along the margins of Pangea. The mantle is treated as an infinite Prandtl number Boussinesq fluid inside a spherical shell with isothermal, undeformable, free-slip boundaries. Nonsubducting rigid blocks to model continental lithosphere are included in the topmost layer of the computational mesh. At the beginning of the numerical experiments these blocks represent the present continents mapped to their approximate Pangean positions. Asymmetrical downwelling at the margins of these nonsubducting blocks results in a pattern of stresses that acts to pull the supercontinent apart. The calculations suggest that the breakup of Pangea and the subsequent global pattern of seafloor spreading was driven largely by the subduction at the Pangean margins.
3-D numerical investigation of the mantle dynamics associated with the breakup of Pangea
Baumgardner, J.R.
1992-10-01
Three-dimensional finite element calculations in spherical geometry are performed to study the response of the mantle with platelike blocks at its surface to an initial condition corresponding to subduction along the margins of Pangea. The mantle is treated as an infinite Prandtl number Boussinesq fluid inside a spherical shell with isothermal, undeformable, free-slip boundaries. Nonsubducting rigid blocks to model continental lithosphere are included in the topmost layer of the computational mesh. At the beginning of the numerical experiments these blocks represent the present continents mapped to their approximate Pangean positions. Asymmetrical downwelling at the margins of these nonsubducting blocks results in a pattern of stresses that acts to pull the supercontinent apart. The calculations suggest that the breakup of Pangea and the subsequent global pattern of seafloor spreading was driven largely by the subduction at the Pangean margins.
Barisch-Fritz, Bettina; Schmeltzpfenning, Timo; Plank, Clemens; Grau, Stefan
2014-01-01
The complex functions of feet require a specific composition, which is progressively achieved by developmental processes. This development should take place without being affected by footwear. The aim of this study is to evaluate differences between static and dynamic foot morphology in developing feet. Feet of 2554 participants (6-16 years) were recorded using a new scanner system (DynaScan4D). Each foot was recorded in static half and full weight-bearing and during walking. Several foot measures corresponding to those used in last construction were calculated. The differences were identified by one-way ANOVA and paired Student's t-test. Static and dynamic values of each foot measure must be considered to improve the fit of footwear. In particular, footwear must account for the increase of forefoot width and the decrease of midfoot girth. Furthermore, the toe box should have a more rounded shape. The findings are important for the construction of footwear for developing feet.
A method of improving the dynamic response of 3D force/torque sensors
NASA Astrophysics Data System (ADS)
Osypiuk, Rafał; Piskorowski, Jacek; Kubus, Daniel
2016-02-01
In the paper attention is drawn to adverse dynamic properties of filters implemented in commercial measurement systems, force/torque sensors, which are increasingly used in industrial robotics. To remedy the problem, it has been proposed to employ a time-variant filter with appropriately modulated parameters, owing to which it is possible to suppress the amplitude of the transient response and, at the same time, to increase the pulsation of damped oscillations; this results in the improvement of dynamic properties in terms of reducing the duration of transients. This property plays a key role in force control and in the fundamental problem of the robot establishing contact with rigid environment. The parametric filters have been verified experimentally and compared with filters available for force/torque sensors manufactured by JR3. The obtained results clearly indicate the advantages of the proposed solution, which may be an interesting alternative to the classic methods of filtration.
NASA Astrophysics Data System (ADS)
Yvonne, Cherubini; Mauro, Cacace; Scheck-Wenderoth, Magdalena
2013-04-01
Faults can provide permeable pathways for fluids at a variety of scales, from great depth in the crust to flow through fractured aquifers, geothermal fields, and hydrocarbon reservoirs (Barton et al. 1995). In terms of geothermal energy exploration, it is essential to understand the role of faults and their impact on the thermal field and fluid system. 3D numerical simulations provide a useful tool for investigating the active physical processes in the subsurface. To assess the influence of major fault zones on the thermal field and fluid system, 3D coupled fluid and heat transport simulations are carried out. The study is based on a recently published structural model of the Brandenburg area, which is located in the south-eastern part of the Northeast German Basin (NEGB) (Noack et al. 2010). Two major fault zones of the Elbe Fault System (Gardelegen and Lausitz Escarpments) vertically offset the pre-Permian basement against the Permian to Cenozoic basin fill at the southern margin by several km (Scheck et al. 2002). Within the numerical models, these two major fault zones are represented as equivalent porous media and vertical discrete elements. The coupled system of equations describing fluid flow and heat transport in saturated porous media are numerically solved by the Finite Element software FEFLOW® (Diersch, 2002). Different possible geological scenarios are modelled and compared to a simulation in which no faults are considered. In one scenario the fault zones are set as impermeable. In this case, the thermal field is similar to the no fault model. Fluid flow is redirected because the fault zones act as hydraulic barriers that prevent a lateral fluid advection into the fault zones. By contrast, modelled permeable fault zones induce a pronounced thermal signature with distinctly cooler temperatures than in the no fault model. Fluid motion within the fault is initially triggered by advection due to hydraulic head gradients, but may be even enhanced by
Haptic perception of force magnitude and its relation to postural arm dynamics in 3D.
van Beek, Femke E; Bergmann Tiest, Wouter M; Mugge, Winfred; Kappers, Astrid M L
2015-12-08
In a previous study, we found the perception of force magnitude to be anisotropic in the horizontal plane. In the current study, we investigated this anisotropy in three dimensional space. In addition, we tested our previous hypothesis that the perceptual anisotropy was directly related to anisotropies in arm dynamics. In experiment 1, static force magnitude perception was studied using a free magnitude estimation paradigm. This experiment revealed a significant and consistent anisotropy in force magnitude perception, with forces exerted perpendicular to the line between hand and shoulder being perceived as 50% larger than forces exerted along this line. In experiment 2, postural arm dynamics were measured using stochastic position perturbations exerted by a haptic device and quantified through system identification. By fitting a mass-damper-spring model to the data, the stiffness, damping and inertia parameters could be characterized in all the directions in which perception was also measured. These results show that none of the arm dynamics parameters were oriented either exactly perpendicular or parallel to the perceptual anisotropy. This means that endpoint stiffness, damping or inertia alone cannot explain the consistent anisotropy in force magnitude perception.
Van, B.T.; Pajon, J.L.; Joseph, P. )
1991-11-01
This paper shows how some simple 3D computer graphics tools can be combined to provide efficient software for visualizing and analyzing data obtained from reservoir simulators and geological simulations. The animation and interactive capabilities of the software quickly provide a deep understanding of the fluid-flow behavior and an accurate idea of the internal architecture of a reservoir.
Body Fluid Dynamics: Back to the Future
Bhave, Gautam; Neilson, Eric G.
2014-01-01
Pioneering investigations conducted over a half century ago on tonicity, transcapillary fluid exchange, and the distribution of water and solute serve as a foundation for understanding the physiology of body fluid spaces. With passage of time, however, some of these concepts have lost their connectivity to more contemporary information. Here we examine the physical forces determining the compartmentalization of body fluid and its movement across capillary and cell membrane barriers, drawing particular attention to the interstitium operating as a dynamic interface for water and solute distribution rather than as a static reservoir. Newer work now supports an evolving model of body fluid dynamics that integrates exchangeable Na+ stores and transcapillary dynamics with advances in interstitial matrix biology. PMID:22034644
Patterns and flow in frictional fluid dynamics
Sandnes, B.; Flekkøy, E.G.; Knudsen, H.A.; Måløy, K.J.; See, H.
2011-01-01
Pattern-forming processes in simple fluids and suspensions have been studied extensively, and the basic displacement structures, similar to viscous fingers and fractals in capillary dominated flows, have been identified. However, the fundamental displacement morphologies in frictional fluids and granular mixtures have not been mapped out. Here we consider Coulomb friction and compressibility in the fluid dynamics, and discover surprising responses including highly intermittent flow and a transition to quasi-continuodynamics. Moreover, by varying the injection rate over several orders of magnitude, we characterize new dynamic modes ranging from stick-slip bubbles at low rate to destabilized viscous fingers at high rate. We classify the fluid dynamics into frictional and viscous regimes, and present a unified description of emerging morphologies in granular mixtures in the form of extended phase diagrams. PMID:21505444
Body fluid dynamics: back to the future.
Bhave, Gautam; Neilson, Eric G
2011-12-01
Pioneering investigations conducted over a half century ago on tonicity, transcapillary fluid exchange, and the distribution of water and solute serve as a foundation for understanding the physiology of body fluid spaces. With passage of time, however, some of these concepts have lost their connectivity to more contemporary information. Here we examine the physical forces determining the compartmentalization of body fluid and its movement across capillary and cell membrane barriers, drawing particular attention to the interstitium operating as a dynamic interface for water and solute distribution rather than as a static reservoir. Newer work now supports an evolving model of body fluid dynamics that integrates exchangeable Na(+) stores and transcapillary dynamics with advances in interstitial matrix biology. PMID:22034644
Computational fluid dynamics modeling of coal gasification in a pressurized spout-fluid bed
Zhongyi Deng; Rui Xiao; Baosheng Jin; He Huang; Laihong Shen; Qilei Song; Qianjun Li
2008-05-15
Computational fluid dynamics (CFD) modeling, which has recently proven to be an effective means of analysis and optimization of energy-conversion processes, has been extended to coal gasification in this paper. A 3D mathematical model has been developed to simulate the coal gasification process in a pressurized spout-fluid bed. This CFD model is composed of gas-solid hydrodynamics, coal pyrolysis, char gasification, and gas phase reaction submodels. The rates of heterogeneous reactions are determined by combining Arrhenius rate and diffusion rate. The homogeneous reactions of gas phase can be treated as secondary reactions. A comparison of the calculated and experimental data shows that most gasification performance parameters can be predicted accurately. This good agreement indicates that CFD modeling can be used for complex fluidized beds coal gasification processes. 37 refs., 7 figs., 5 tabs.
Schultz, Kelly M.; Kyburz, Kyle A.; Anseth, Kristi S.
2015-01-01
Biomaterials that mimic aspects of the extracellular matrix by presenting a 3D microenvironment that cells can locally degrade and remodel are finding increased applications as wound-healing matrices, tissue engineering scaffolds, and even substrates for stem cell expansion. In vivo, cells do not simply reside in a static microenvironment, but instead, they dynamically reengineer their surroundings. For example, cells secrete proteases that degrade extracellular components, attach to the matrix through adhesive sites, and can exert traction forces on the local matrix, causing its spatial reorganization. Although biomaterials scaffolds provide initially well-defined microenvironments for 3D culture of cells, less is known about the changes that occur over time, especially local matrix remodeling that can play an integral role in directing cell behavior. Here, we use microrheology as a quantitative tool to characterize dynamic cellular remodeling of peptide-functionalized poly(ethylene glycol) (PEG) hydrogels that degrade in response to cell-secreted matrix metalloproteinases (MMPs). This technique allows measurement of spatial changes in material properties during migration of encapsulated cells and has a sensitivity that identifies regions where cells simply adhere to the matrix, as well as the extent of local cell remodeling of the material through MMP-mediated degradation. Collectively, these microrheological measurements provide insight into microscopic, cellular manipulation of the pericellular region that gives rise to macroscopic tracks created in scaffolds by migrating cells. This quantitative and predictable information should benefit the design of improved biomaterial scaffolds for medically relevant applications. PMID:26150508
Hirashima, Masaya; Kudo, Kazutoshi; Watarai, Koji; Ohtsuki, Tatsuyuki
2007-01-01
This study investigated how the human CNS organizes complex three-dimensional (3D) ball-throwing movements that require both speed and accuracy. Skilled baseball players threw a baseball to a target at three different speeds. Kinematic analysis revealed that the fingertip speed at ball release was mainly produced by trunk leftward rotation, shoulder internal rotation, elbow extension, and wrist flexion in all speed conditions. The study participants adjusted the angular velocities of these four motions to throw the balls at three different speeds. We also analyzed the dynamics of the 3D multijoint movements using a recently developed method called "nonorthogonal torque decomposition" that can clarify how angular acceleration about a joint coordinate axis (e.g., shoulder internal rotation) is generated by the muscle, gravity, and interaction torques. We found that the study participants utilized the interaction torque to generate larger angular velocities of the shoulder internal rotation, elbow extension, and wrist flexion. To increase the interaction torque acting at these joints, the ball throwers increased muscle torque at the shoulder and trunk but not at the elbow and wrist. These results indicates that skilled ball throwers adopted a hierarchical control in which the proximal muscle torques created a dynamic foundation for the entire limb motion and beneficial interaction torques for distal joint rotations.
NASA Astrophysics Data System (ADS)
Alekseenko, Elena; Raybaud, Virginie; Espinasse, Boris; Carlotti, François; Queguiner, Bernard; Thouvenin, Bénédicte; Garreau, Pierre; Baklouti, Melika
2014-01-01
The 3D hydrodynamic Model for Applications at Regional Scale (MARS3D) was coupled with a biogeochemical model developed with the Ecological Modular Mechanistic Modelling (Eco3M) numerical tool. The three-dimensional coupled model was applied to the NW Mediterranean Sea to study the dynamics of the key biogeochemical processes in the area in relation with hydrodynamic constraints. In particular, we focused on the temporal and spatial variability of intracellular contents of living and non-living compartments. The conceptual scheme of the biogeochemical model accounts for the complex food web of the NW Mediterranean Sea (34 state variables), using flexible plankton stoichiometry. We used mechanistic formulations to describe most of the biogeochemical processes involved in the dynamics of marine pelagic ecosystems. Simulations covered the period from September 1, 2009 to January 31, 2011 (17 months), which enabled comparison of model outputs with situ measurements made during two oceanographic cruises in the region (Costeau-4: April 27-May 2, 2010 and Costeau-6: January 23-January 27, 2011).
KMOS3D: Dynamical Constraints on the Mass Budget in Early Star-forming Disks
NASA Astrophysics Data System (ADS)
Wuyts, Stijn; Förster Schreiber, Natascha M.; Wisnioski, Emily; Genzel, Reinhard; Burkert, Andreas; Bandara, Kaushala; Beifiori, Alessandra; Belli, Sirio; Bender, Ralf; Brammer, Gabriel B.; Chan, Jeffrey; Davies, Ric; Fossati, Matteo; Galametz, Audrey; Kulkarni, Sandesh K.; Lang, Philipp; Lutz, Dieter; Mendel, J. Trevor; Momcheva, Ivelina G.; Naab, Thorsten; Nelson, Erica J.; Saglia, Roberto P.; Seitz, Stella; Tacconi, Linda J.; Tadaki, Ken-ichi; Übler, Hannah; van Dokkum, Pieter G.; Wilman, David J.; Wuyts, Eva
2016-11-01
We exploit deep integral-field spectroscopic observations with KMOS/Very Large Telescope of 240 star-forming disks at 0.6\\lt z\\lt 2.6 to dynamically constrain their mass budget. Our sample consists of massive (≳ {10}9.8 {M}ȯ ) galaxies with sizes {R}e≳ 2 {kpc}. By contrasting the observed velocity and dispersion profiles with dynamical models, we find that on average the stellar content contributes {32}-7+8 % of the total dynamical mass, with a significant spread among galaxies (68th percentile range {f}{star}∼ 18 % {--}62 % ). Including molecular gas as inferred from CO- and dust-based scaling relations, the estimated baryonic mass adds up to {56}-12+17 % of the total for the typical galaxy in our sample, reaching ∼ 90 % at z\\gt 2. We conclude that baryons make up most of the mass within the disk regions of high-redshift star-forming disk galaxies, with typical disks at z\\gt 2 being strongly baryon-dominated within R e . Substantial object-to-object variations in both stellar and baryonic mass fractions are observed among the galaxies in our sample, larger than what can be accounted for by the formal uncertainties in their respective measurements. In both cases, the mass fractions correlate most strongly with measures of surface density. High-{{{Σ }}}{star} galaxies feature stellar mass fractions closer to unity, and systems with high inferred gas or baryonic surface densities leave less room for additional mass components other than stars and molecular gas. Our findings can be interpreted as more extended disks probing further (and more compact disks probing less far) into the dark matter halos that host them. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programs 092.A-0091, 093.A-0079, 094.A-0217, 095.A-0047, and 096.A-0025.
NASA Astrophysics Data System (ADS)
Dutta, Ritaban; Cohn, Anthony G.; Muggleton, Jen M.
2013-05-01
The successful operation of buried infrastructure within urban environments is fundamental to the conservation of modern living standards. In this paper a novel multi-sensor image fusion framework has been proposed and investigated using dynamic Bayesian network for automatic detection of buried underworld infrastructure. Experimental multi-sensors images were acquired for a known buried plastic water pipe using Vibro-acoustic sensor based location methods and Ground Penetrating Radar imaging system. Computationally intelligent conventional image processing techniques were used to process three types of sensory images. Independently extracted depth and location information from different images regarding the target pipe were fused together using dynamic Bayesian network to predict the maximum probable location and depth of the pipe. The outcome from this study was very encouraging as it was able to detect the target pipe with high accuracy compared with the currently existing pipe survey map. The approach was also applied successfully to produce a best probable 3D buried asset map.
NASA Astrophysics Data System (ADS)
Pathak, Ashish; Raessi, Mehdi
2016-04-01
We present a three-dimensional (3D) and fully Eulerian approach to capturing the interaction between two fluids and moving rigid structures by using the fictitious domain and volume-of-fluid (VOF) methods. The solid bodies can have arbitrarily complex geometry and can pierce the fluid-fluid interface, forming contact lines. The three-phase interfaces are resolved and reconstructed by using a VOF-based methodology. Then, a consistent scheme is employed for transporting mass and momentum, allowing for simulations of three-phase flows of large density ratios. The Eulerian approach significantly simplifies numerical resolution of the kinematics of rigid bodies of complex geometry and with six degrees of freedom. The fluid-structure interaction (FSI) is computed using the fictitious domain method. The methodology was developed in a message passing interface (MPI) parallel framework accelerated with graphics processing units (GPUs). The computationally intensive solution of the pressure Poisson equation is ported to GPUs, while the remaining calculations are performed on CPUs. The performance and accuracy of the methodology are assessed using an array of test cases, focusing individually on the flow solver and the FSI in surface-piercing configurations. Finally, an application of the proposed methodology in simulations of the ocean wave energy converters is presented.
MERIDIONAL CIRCULATION DYNAMICS FROM 3D MAGNETOHYDRODYNAMIC GLOBAL SIMULATIONS OF SOLAR CONVECTION
Passos, Dário; Charbonneau, Paul; Miesch, Mark
2015-02-10
The form of solar meridional circulation is a very important ingredient for mean field flux transport dynamo models. However, a shroud of mystery still surrounds this large-scale flow, given that its measurement using current helioseismic techniques is challenging. In this work, we use results from three-dimensional global simulations of solar convection to infer the dynamical behavior of the established meridional circulation. We make a direct comparison between the meridional circulation that arises in these simulations and the latest observations. Based on our results, we argue that there should be an equatorward flow at the base of the convection zone at mid-latitudes, below the current maximum depth helioseismic measures can probe (0.75 R{sub ⊙}). We also provide physical arguments to justify this behavior. The simulations indicate that the meridional circulation undergoes substantial changes in morphology as the magnetic cycle unfolds. We close by discussing the importance of these dynamical changes for current methods of observation which involve long averaging periods of helioseismic data. Also noteworthy is the fact that these topological changes indicate a rich interaction between magnetic fields and plasma flows, which challenges the ubiquitous kinematic approach used in the vast majority of mean field dynamo simulations.
3D dislocation dynamics: stress-strain behavior and hardening mechanisms in FCC and BCC metals
Hirth, J P; Rhee, M; Zhib, H M; de la Rubia, T D
1999-02-19
A dislocation dynamics (DD) model for plastic deformation, connecting the macroscopic mechanical properties to basic physical laws governing dislocation mobility and related interaction mechanisms, has been under development. In this model there is a set of critical reactions that determine the overall results of the simulations, such as the stress-strain curve. These reactions are, annihilation, formation of jogs, junctions, and dipoles, and cross-slip. In this paper we discuss these reactions and the manner in which they influence the simulated stress- strain behavior in fcc and bcc metals. In particular, we examine the formation (zipping) and strength of dipoles and junctions, and effect of jogs, using the dislocation dynamics model. We show that the strengths (unzipping) of these reactions for various configurations can be determined by direct evaluation of the elastic interactions. Next, we investigate the phenomenon of hardening in metals subjected to cascade damage dislocations. The microstructure investigated consists of small dislocation loops decorating the mobile dislocations. Preliminary results reveal that these loops act as hardening agents, trapping the dislocations and resulting in increased hardening.
Dynamic 3D shape of the plantar surface of the foot using coded structured light: a technical report
2014-01-01
Background The foot provides a crucial contribution to the balance and stability of the musculoskeletal system, and accurate foot measurements are important in applications such as designing custom insoles/footwear. With better understanding of the dynamic behavior of the foot, dynamic foot reconstruction techniques are surfacing as useful ways to properly measure the shape of the foot. This paper presents a novel design and implementation of a structured-light prototype system providing dense three dimensional (3D) measurements of the foot in motion. The input to the system is a video sequence of a foot during a single step; the output is a 3D reconstruction of the plantar surface of the foot for each frame of the input. Methods Engineering and clinical tests were carried out to test the accuracy and repeatability of the system. Accuracy experiments involved imaging a planar surface from different orientations and elevations and measuring the fitting errors of the data to a plane. Repeatability experiments were done using reconstructions from 27 different subjects, where for each one both right and left feet were reconstructed in static and dynamic conditions over two different days. Results The static accuracy of the system was found to be 0.3 mm with planar test objects. In tests with real feet, the system proved repeatable, with reconstruction differences between trials one week apart averaging 2.4 mm (static case) and 2.8 mm (dynamic case). Conclusion The results obtained in the experiments show positive accuracy and repeatability results when compared to current literature. The design also shows to be superior to the systems available in the literature in several factors. Further studies need to be done to quantify the reliability of the system in clinical environments. PMID:24456711
Zhu, Jian Hua; Lee, Heow Pueh; Lim, Kian Meng; Lee, Shu Jin; Teo, Li San Lynette; Wang, De Yun
2012-07-26
This study reconstructed a three dimensional fluid/structure interaction (FSI) model to investigate the compliance of human soft palate during calm respiration. Magnetic resonance imaging scans of a healthy male subject were obtained for model reconstruction of the upper airway and the soft palate. The fluid domain consists of nasal cavity, nasopharynx and oropharynx. The airflow in upper airway was assumed as laminar and incompressible. The soft palate was assumed as linear elastic. The interface between airway and soft palate was the FSI interface. Sinusoidal variation of velocity magnitude was applied at the oropharynx corresponding to ventilation rate of 7.5L/min. Simulations of fluid model in upper airway, FSI models with palatal Young's modulus of 7539Pa and 3000Pa were carried out for two cycles of respiration. The results showed that the integrated shear forces over the FSI interface were much smaller than integrated pressure forces in all the three directions (axial, coronal and sagittal). The total integrated force in sagittal direction was much smaller than that of coronal and axial directions. The soft palate was almost static during inspiration but moved towards the posterior pharyngeal wall during expiration. In conclusion, the displacement of human soft palate during respiration was mainly driven by air pressure around the surface of the soft palate with minimal contribution of shear stress of the upper airway flow. Despite inspirational negative pressure, expiratory posterior movement of soft palate could be another factor for the induction of airway collapse.
Solvent-modified dynamic porosity in chiral 3D kagome frameworks.
Keene, Tony D; Rankine, Damien; Evans, Jack D; Southon, Peter D; Kepert, Cameron J; Aitken, Jade B; Sumby, Christopher J; Doonan, Christian J
2013-06-14
Dynamically porous metal-organic frameworks (MOFs) with a chiral quartz-based structure have been synthesized from the multidentate ligand 2,2'-dihydroxybiphenyl-4,4'-dicarboxylate (H2diol). Compounds [Ni(II)(H2diol)(S)2]·xS (where S = DMF or DEF) show marked changes in 77 K N2 uptake between partially desolvated [Ni(II)(H2diol)(S)2] (only the pore solvent is removed) and fully desolvated [Ni(II)(H2diol)] forms. Furthermore, [Ni(II)(H2diol)(DMF)2] displays additional solvent-dependent porosity through the rotation of DMF molecules attached to the axial coordination sites of the Ni(II) centre. A unique feature of the four coordinate Ni(II) centre in [Ni(II)(H2diol)] is the dynamic response to its chemical environment. Exposure of [Ni(II)(H2diol)] to H2O and MeOH vapour leads to coordination of both axial sites of the Ni centres and to the generation of a solvated framework, whereas exposure to EtOH, DMF, acetone, and MeCN does not lead to any change in metal coordination or structure metrics. MeOH vapour adsorption was able to be tracked by time-dependent magnetometry as the solvated and desolvated structures have different magnetic moments. Solvated and desolvated forms of the MOF show remarkable differences in their thermal expansivities; [Ni(II)(H2diol)(DMF)2]·DMF displays marked positive thermal expansion (PTE) in the c-axis, yet near to zero thermal expansion, between 90 and 450 K, is observed for [Ni(II)(H2diol)]. These new MOF architectures demonstrate a dynamic structural and colourimetric response to selected adsorbates via a unique mechanism that involves a reversible change in the coordination environment of the metal centre. These coordination changes are mediated throughout the MOF by rotational mobility about the biaryl bond of the ligand.
REMOVAL OF TANK AND SEWER SEDIMENT BY GATE FLUSHING: COMPUTATIONAL FLUID DYNAMICS MODEL STUDIES
This presentation will discuss the application of a computational fluid dynamics 3D flow model to simulate gate flushing for removing tank/sewer sediments. The physical model of the flushing device was a tank fabricated and installed at the head-end of a hydraulic flume. The fl...
Dynamic mineral clouds on HD 189733b. I. 3D RHD with kinetic, non-equilibrium cloud formation
NASA Astrophysics Data System (ADS)
Lee, G.; Dobbs-Dixon, I.; Helling, Ch.; Bognar, K.; Woitke, P.
2016-10-01
Context. Observations of exoplanet atmospheres have revealed the presence of cloud particles in their atmospheres. 3D modelling of cloud formation in atmospheres of extrasolar planets coupled to the atmospheric dynamics has long been a challenge. Aims: We investigate the thermo-hydrodynamic properties of cloud formation processes in the atmospheres of hot Jupiter exoplanets. Methods: We simulate the dynamic atmosphere of HD 189733b with a 3D model that couples 3D radiative-hydrodynamics with a kinetic, microphysical mineral cloud formation module designed for RHD/GCM exoplanet atmosphere simulations. Our simulation includes the feedback effects of cloud advection and settling, gas phase element advection and depletion/replenishment and the radiative effects of cloud opacity. We model the cloud particles as a mix of mineral materials which change in size and composition as they travel through atmospheric thermo-chemical environments. All local cloud properties such as number density, grain size and material composition are time-dependently calculated. Gas phase element depletion as a result of cloud formation is included in the model. In situ effective medium theory and Mie theory is applied to calculate the wavelength dependent opacity of the cloud component. Results: We present a 3D cloud structure of a chemically complex, gaseous atmosphere of the hot Jupiter HD 189733b. Mean cloud particle sizes are typically sub-micron (0.01-0.5 μm) at pressures less than 1 bar with hotter equatorial regions containing the smallest grains. Denser cloud structures occur near terminator regions and deeper (~1 bar) atmospheric layers. Silicate materials such as MgSiO3[s] are found to be abundant at mid-high latitudes, while TiO2[s] and SiO2[s] dominate the equatorial regions. Elements involved in the cloud formation can be depleted by several orders of magnitude. Conclusions: The interplay between radiative-hydrodynamics and cloud kinetics leads to an inhomogeneous, wavelength
Dynamic force measurements for a high bar using 3D motion capturing.
Cagran, C; Huber, P; Müller, W
2010-03-01
The displacement of a calibrated horizontal bar is used as a measure for forces acting on the bar itself during dynamic performances in artistic gymnastics. The high bar is loaded with known forces and the displacement is monitored by means of a Vicon motion capturing system. The calibration results are fitted according to the Euler-Bernoulli beam theory. After calibration, forces can straightforwardly be measured by multiplication of the bar displacement with the determined fit parameter. This approach is also able to account for non-central force application (two hands on the bar) and the effect of the bar's inertia. Uncertainties in measured forces are assessed to be +/-25 N plus an additional 1% for the unknown weight distribution between the two hands. PMID:19906379
Base and salt 3D forms of Emeraldine II polymers by Car-Parrinello molecular dynamics
NASA Astrophysics Data System (ADS)
Cavazzoni, Carlo; Colle, Renato; Farchioni, Riccardo; Grosso, Giuseppe
2005-07-01
We have studied structural and electronic properties of the three-dimensional crystalline regions of Emeraldine II polymers, in the base (EB-II) and salt (ES-II) forms, by means of first principle Car-Parrinello molecular dynamics. We compare the geometrical structures of the polymer chains in the primitive cells of EB-II and ES-II, pointing out the structural effects due to the protonation with HCl of the iminic nitrogens in the EB-II chains, and the effect of the counterions between neighboring chains. We also analyze the HOMO electron density distribution, band structure and density of states of the resulting bipolaronic structure of ES-II, which is energetically stable and maintains semiconductor character.
A 3D model for α Gem AB: orbits and dynamics
NASA Astrophysics Data System (ADS)
Docobo, José A.; Andrade, Manuel; Campo, Pedro P.; Ling, Josefina F.
2016-01-01
The well-known multiple star system, Castor, and particularly, the [(Aa, Ab), (Ba, Bb)] subsystem, was studied in detail. After a rigorous analysis of the quality controls, a new solution for the visual orbit yielded new values for the different physical and orbital parameters of the system. In addition, a comprehensive investigation of the orbital configuration of the quadruple system allowed us to provide both accurate individual masses and orbital inclinations of the spectroscopic subcomponents, as well as a new value of its orbital parallax. Finally, by means of a numerical analysis of the long-term dynamics, we obtained the most probable values of the nodal angles of the two spectroscopic subsystems for the first time.
NASA Astrophysics Data System (ADS)
Borovkov, Alexei I.; Pyatishev, Evgenij N.; Lurie, Mihail S.; Korshunov, Andrey V.; Akulshin, Y. D.; Dolganov, A. G.; Sabadash, V. O.
2000-02-01
The tiny engines, founded on the principle of reactive thrust, are one of most perspective actuators developed by modern micromechanics. These engines can be applied for such apparent problems, as orientation and stabilization of small space objects, but also as local or distributed reactive thrust of new phylum of aerospace objects, for control of boundary layer of flying objects and in series of converting power devices of different purposes. Distinctive features of jet tiny engines are profitability (very large thrust-to-weight ratio) and high (milliseconds) response, which makes them to irreplaceable elements in control systems and, specially, in distributed power generations. These features are provided the minimum sizes, high pressure in working chambers and hypersonic velocity of propulsive jet. Topologically micronozzles are designed as the flat batch devices (3 layers as minimum). The lower and upper layers make flat walls of the nozzle and mainly influence on strength properties of the device. The mean layer reshapes geometry and determines gas dynamic characteristic of the nozzle. A special problem is the opening-up of the combustion-mixture, which is not esteemed in this work. It is necessary to allow for effect of considerable local stresses arising at the expense of static and dynamic loading at design of the jet tiny engines. Thermal gas dynamic processes in the chamber and nozzle determine the values and nature of these stresses, which are hardly studied for the microdevices. The priority is mathematical and experimental simulation of these processes. The most suitable object for initial phase of experimental simulation is the 'cold' engine. The demanded chamber static pressure is formed by external compressed air. In Laboratory of Microtechnology and MicroElectroMechanical Systems a number of such tiny engines with different shapes of the chamber's and the nozzles' surfaces were designed, made and tested. The engines were produced from photosensing
NASA Astrophysics Data System (ADS)
Borovkov, Alexei I.; Pyatishev, Evgenij N.; Lurie, Mihail S.; Korshunov, Andrey V.; Akulshin, Y. D.; Dolganov, A. G.; Sabadash, V. O.
2001-02-01
The tiny engines, founded on the principle of reactive thrust, are one of most perspective actuators developed by modern micromechanics. These engines can be applied for such apparent problems, as orientation and stabilization of small space objects, but also as local or distributed reactive thrust of new phylum of aerospace objects, for control of boundary layer of flying objects and in series of converting power devices of different purposes. Distinctive features of jet tiny engines are profitability (very large thrust-to-weight ratio) and high (milliseconds) response, which makes them to irreplaceable elements in control systems and, specially, in distributed power generations. These features are provided the minimum sizes, high pressure in working chambers and hypersonic velocity of propulsive jet. Topologically micronozzles are designed as the flat batch devices (3 layers as minimum). The lower and upper layers make flat walls of the nozzle and mainly influence on strength properties of the device. The mean layer reshapes geometry and determines gas dynamic characteristic of the nozzle. A special problem is the opening-up of the combustion-mixture, which is not esteemed in this work. It is necessary to allow for effect of considerable local stresses arising at the expense of static and dynamic loading at design of the jet tiny engines. Thermal gas dynamic processes in the chamber and nozzle determine the values and nature of these stresses, which are hardly studied for the microdevices. The priority is mathematical and experimental simulation of these processes. The most suitable object for initial phase of experimental simulation is the 'cold' engine. The demanded chamber static pressure is formed by external compressed air. In Laboratory of Microtechnology and MicroElectroMechanical Systems a number of such tiny engines with different shapes of the chamber's and the nozzles' surfaces were designed, made and tested. The engines were produced from photosensing
3-D Reconstruction of Structure and Dynamics of Coronal Twistors From STEREO and SDO Imagery
NASA Astrophysics Data System (ADS)
Slater, G. L.; Freeland, S. L.
2014-12-01
Although observed anecdotally for decades in H-alpha and EUV, so-called coronal 'tornadoes' have only recently become the focus of systematic and quantitative study and modeling. This increased focus has primarily been driven by data from the SDO observatory and more recently the IRIS observatory and ground-based telescopes. These ubiquitous magnetic structures differ in appearance and apparent dynamics depending upon position on the sun relative to the observer and upon observational wavelength. One of the key outstanding questions is whether they are actually rotating structures. Progress has been made using spectroscopic observations (IRIS, etc.) but the question is still not settled. We will present true stereographic movies of a set of these structures at various locations on the sun, using combinations of simultaneous STEREO and SDO imagery, in order to address the question of the actual motion of the structures.
Morphology and Dynamics of Solar Prominences from 3D MHD Simulations
NASA Astrophysics Data System (ADS)
Terradas, J.; Soler, R.; Luna, M.; Oliver, R.; Ballester, J. L.
2015-01-01
In this paper we present a numerical study of the time evolution of solar prominences embedded in sheared magnetic arcades. The prominence is represented by a density enhancement in a background-stratified atmosphere and is connected to the photosphere through the magnetic field. By solving the ideal magnetohydrodynamic equations in three dimensions, we study the dynamics for a range of parameters representative of real prominences. Depending on the parameters considered, we find prominences that are suspended above the photosphere, i.e., detached prominences, but also configurations resembling curtain or hedgerow prominences whose material continuously connects to the photosphere. The plasma-β is an important parameter that determines the shape of the structure. In many cases magnetic Rayleigh-Taylor instabilities and oscillatory phenomena develop. Fingers and plumes are generated, affecting the whole prominence body and producing vertical structures in an essentially horizontal magnetic field. However, magnetic shear is able to reduce or even to suppress this instability.
A parallel dynamic load balancing algorithm for 3-D adaptive unstructured grids
NASA Technical Reports Server (NTRS)
Vidwans, A.; Kallinderis, Y.; Venkatakrishnan, V.
1993-01-01
Adaptive local grid refinement and coarsening results in unequal distribution of workload among the processors of a parallel system. A novel method for balancing the load in cases of dynamically changing tetrahedral grids is developed. The approach employs local exchange of cells among processors in order to redistribute the load equally. An important part of the load balancing algorithm is the method employed by a processor to determine which cells within its subdomain are to be exchanged. Two such methods are presented and compared. The strategy for load balancing is based on the Divide-and-Conquer approach which leads to an efficient parallel algorithm. This method is implemented on a distributed-memory MIMD system.
Interfacial gauge methods for incompressible fluid dynamics.
Saye, Robert
2016-06-01
Designing numerical methods for incompressible fluid flow involving moving interfaces, for example, in the computational modeling of bubble dynamics, swimming organisms, or surface waves, presents challenges due to the coupling of interfacial forces with incompressibility constraints. A class of methods, denoted interfacial gauge methods, is introduced for computing solutions to the corresponding incompressible Navier-Stokes equations. These methods use a type of "gauge freedom" to reduce the numerical coupling between fluid velocity, pressure, and interface position, allowing high-order accurate numerical methods to be developed more easily. Making use of an implicit mesh discontinuous Galerkin framework, developed in tandem with this work, high-order results are demonstrated, including surface tension dynamics in which fluid velocity, pressure, and interface geometry are computed with fourth-order spatial accuracy in the maximum norm. Applications are demonstrated with two-phase fluid flow displaying fine-scaled capillary wave dynamics, rigid body fluid-structure interaction, and a fluid-jet free surface flow problem exhibiting vortex shedding induced by a type of Plateau-Rayleigh instability. The developed methods can be generalized to other types of interfacial flow and facilitate precise computation of complex fluid interface phenomena. PMID:27386567
Interfacial gauge methods for incompressible fluid dynamics
Saye, Robert
2016-01-01
Designing numerical methods for incompressible fluid flow involving moving interfaces, for example, in the computational modeling of bubble dynamics, swimming organisms, or surface waves, presents challenges due to the coupling of interfacial forces with incompressibility constraints. A class of methods, denoted interfacial gauge methods, is introduced for computing solutions to the corresponding incompressible Navier-Stokes equations. These methods use a type of “gauge freedom” to reduce the numerical coupling between fluid velocity, pressure, and interface position, allowing high-order accurate numerical methods to be developed more easily. Making use of an implicit mesh discontinuous Galerkin framework, developed in tandem with this work, high-order results are demonstrated, including surface tension dynamics in which fluid velocity, pressure, and interface geometry are computed with fourth-order spatial accuracy in the maximum norm. Applications are demonstrated with two-phase fluid flow displaying fine-scaled capillary wave dynamics, rigid body fluid-structure interaction, and a fluid-jet free surface flow problem exhibiting vortex shedding induced by a type of Plateau-Rayleigh instability. The developed methods can be generalized to other types of interfacial flow and facilitate precise computation of complex fluid interface phenomena. PMID:27386567
NASA Astrophysics Data System (ADS)
Bustamante, Miguel D.
2014-11-01
We consider 3D Euler fluids endowed with a discrete symmetry whereby the velocity field is invariant under mirror reflections about a 2D surface known as the ``symmetry plane.'' This type of flow is widely used in numerical simulations of classical/magnetic/quantum turbulence and vortex reconnection. On the 2D symmetry plane, the governing equations are best written in terms of two scalars: vorticity and stretching rate of vorticity. These determine the velocity field on the symmetry plane. However, the governing equations are not closed, because of the contribution of a single pressure term that depends on the full 3D velocity profile. By modelling this pressure term we propose a one-parameter family of sensible models for the flow along the 2D symmetry plane. We apply the method of infinitesimal Lie symmetries and solve the governing equations analytically for the two scalars as functions of time. We show how the value of the model's parameter determines if the analytical solution has a finite-time blowup and obtain explicit formulae for the blowup time. We validate the models by showing that a particular choice of the model's parameter corresponds to a well-known exact solution of 3D Euler equations [Gibbon et al., Physica D 132, 497 (1999)]. We discuss practical applications. Supported by Science Foundation Ireland (SFI) under Grant Number 12/IP/1491.
A full 3D model of fluid flow and heat transfer in an E.B. heated liquid metal bath
NASA Astrophysics Data System (ADS)
Matveichev, A.; Jardy, A.; Bellot, J. P.
2016-07-01
In order to study the dissolution of exogeneous inclusions in the liquid metal during processing of titanium alloys, a series of dipping experiments has been performed in an Electron Beam Melting laboratory furnace. Precise determination of the dissolution kinetics requires knowing and mastering the exact thermohydrodynamic behavior of the melt pool, which implies full 3D modeling of the process. To achieve this goal, one needs to describe momentum and heat transfer, phase change, as well as the development of flow turbulence in the liquid. EB power input, thermal radiation, heat loss through the cooling circuit, surface tension effects (i.e. Marangoni-induced flow) must also be addressed in the model. Therefore a new solver dealing with all these phenomena was implemented within OpenFOAM platform. Numerical results were compared with experimental data from actual Ti melting, showing a pretty good agreement. In the second stage, the immersion of a refractory sample rod in the liquid pool was simulated. Results of the simulations showed that the introduction of the sample slightly disturbs the flow field inside the bath. The amount of such disturbance depends on the exact location of the dipping.
NASA Astrophysics Data System (ADS)
Ohira, Katsuhide; Ota, Atsuhito; Mukai, Yasuaki; Hosono, Takumi
2012-07-01
Cryogenic slush fluids, such as slush hydrogen and slush nitrogen, are two-phase, single-component fluids containing solid particles in a liquid. Since their density and refrigerant capacity are greater than those of liquid-state fluids alone, there are high expectations for use of slush fluids as functionally thermal fluids in various applications, such as fuels for spacecraft engines, clean energy fuels to improve the efficiency of transportation and storage, and as refrigerants for high-temperature superconducting equipment. In this research, a three-dimensional numerical simulation code (SLUSH-3D), including the gravity effect based on the thermal non-equilibrium, two-fluid model, was constructed to clarify the flow and heat-transfer characteristics of cryogenic slush fluids in a horizontal circular pipe. The calculated results of slush nitrogen flow performed using the numerical code were compared with the authors' experimental results obtained using the PIV method. As a result of these comparisons, the numerical code was verified, making it possible to analyze the flow and heat-transfer characteristics of slush nitrogen with sufficient accuracy. The numerical results obtained for the flow and heat-transfer characteristics of slush nitrogen and slush hydrogen clarified the effects of the pipe inlet velocity, solid fraction, solid particle size, and heat flux on the flow pattern, solid-fraction distribution, turbulence energy, pressure drop, and heat-transfer coefficient. Furthermore, it became clear that the difference of the flow and heat-transfer characteristics between slush nitrogen and slush hydrogen were caused to a large extent by their thermo-physical properties, such as the solid-liquid density ratio, liquid viscosity, and latent heat of fusion.
A molecular dynamics implementation of the 3D Mercedes-Benz water model
NASA Astrophysics Data System (ADS)
Hynninen, T.; Dias, C. L.; Mkrtchyan, A.; Heinonen, V.; Karttunen, M.; Foster, A. S.; Ala-Nissila, T.
2012-02-01
The three-dimensional Mercedes-Benz model was recently introduced to account for the structural and thermodynamic properties of water. It treats water molecules as point-like particles with four dangling bonds in tetrahedral coordination, representing H-bonds of water. Its conceptual simplicity renders the model attractive in studies where complex behaviors emerge from H-bond interactions in water, e.g., the hydrophobic effect. A molecular dynamics (MD) implementation of the model is non-trivial and we outline here the mathematical framework of its force-field. Useful routines written in modern Fortran are also provided. This open source code is free and can easily be modified to account for different physical context. The provided code allows both serial and MPI-parallelized execution. Program summaryProgram title: CASHEW (Coarse Approach Simulator for Hydrogen-bonding Effects in Water) Catalogue identifier: AEKM_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEKM_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 20 501 No. of bytes in distributed program, including test data, etc.: 551 044 Distribution format: tar.gz Programming language: Fortran 90 Computer: Program has been tested on desktop workstations and a Cray XT4/XT5 supercomputer. Operating system: Linux, Unix, OS X Has the code been vectorized or parallelized?: The code has been parallelized using MPI. RAM: Depends on size of system, about 5 MB for 1500 molecules. Classification: 7.7 External routines: A random number generator, Mersenne Twister ( http://www.math.sci.hiroshima-u.ac.jp/m-mat/MT/VERSIONS/FORTRAN/mt95.f90), is used. A copy of the code is included in the distribution. Nature of problem: Molecular dynamics simulation of a new geometric water model. Solution method: New force-field for
NASA Astrophysics Data System (ADS)
Guillaume, B.; Funiciello, F.; Moroni, M.; Faccenna, C.; Martinod, J.
2009-12-01
Slab window can form either by the intersection of a spreading ridge with a subduction zone or because of internal deformation of the slab that leads to its disruption. The main consequences of this phenomenon are the modifications of the physical, chemical and thermal conditions in the backarc mantle that in turn affect the tectonic and magmatic evolution of the overriding plate. We performed laboratory models of a two-layer linear viscous slab (silicone putty)-upper mantle (glucose syrup) system to quantitatively investigate the pattern of mantle circulation within the slab window (using Feature Tracking image analysis technique) and its influence on the kinematics of the system. Two different geometries have been tested considering a window located (a) at slab edges or (b) within the slab. Kinematic consequences of slab window have been explored to understand the dynamics of the mantle-slab interaction. Configuration (a) implies a reduction of the slab width (W) during subduction and is characterized by toroidal fluxes around the slab edges. The abrupt opening of lateral slab windows produces an acceleration of the trench retreat and subduction velocity, such as 40% for a three-fold width reduction. We interpret this behavior as mostly due to the decrease in the toroidal flow inside subduction windows, scaling with W2. Configuration (b) has been designed to explore the pattern of mantle flow within the window in the case of a laterally constrained subduction system. Slab window, which had a width (Ww) fixed to 15 % of the slab width, opened in the trench-perpendicular direction. It produced the formation of two toroidal mantle cells, centered on the slab midpoint and laterally growing as the slab window enlarged. Particles extruded through the slab window did not mix with particles located in the mantle wedge, the boundary between both reaching distances from the trench up to 3×Ww in the trench-perpendicular direction, and up to 1.5×Ww from the window edge in
NASA Astrophysics Data System (ADS)
Draper, Martin; Usera, Gabriel
2015-04-01
The Scale Dependent Dynamic Model (SDDM) has been widely validated in large-eddy simulations using pseudo-spectral codes [1][2][3]. The scale dependency, particularly the potential law, has been proved also in a priori studies [4][5]. To the authors' knowledge there have been only few attempts to use the SDDM in finite difference (FD) and finite volume (FV) codes [6][7], finding some improvements with the dynamic procedures (scale independent or scale dependent approach), but not showing the behavior of the scale-dependence parameter when using the SDDM. The aim of the present paper is to evaluate the SDDM in the open source code caffa3d.MBRi, an updated version of the code presented in [8]. caffa3d.MBRi is a FV code, second-order accurate, parallelized with MPI, in which the domain is divided in unstructured blocks of structured grids. To accomplish this, 2 cases are considered: flow between flat plates and flow over a rough surface with the presence of a model wind turbine, taking for this case the experimental data presented in [9]. In both cases the standard Smagorinsky Model (SM), the Scale Independent Dynamic Model (SIDM) and the SDDM are tested. As presented in [6][7] slight improvements are obtained with the SDDM. Nevertheless, the behavior of the scale-dependence parameter supports the generalization of the dynamic procedure proposed in the SDDM, particularly taking into account that no explicit filter is used (the implicit filter is unknown). [1] F. Porté-Agel, C. Meneveau, M.B. Parlange. "A scale-dependent dynamic model for large-eddy simulation: application to a neutral atmospheric boundary layer". Journal of Fluid Mechanics, 2000, 415, 261-284. [2] E. Bou-Zeid, C. Meneveau, M. Parlante. "A scale-dependent Lagrangian dynamic model for large eddy simulation of complex turbulent flows". Physics of Fluids, 2005, 17, 025105 (18p). [3] R. Stoll, F. Porté-Agel. "Dynamic subgrid-scale models for momentum and scalar fluxes in large-eddy simulations of
The development of an intelligent interface to a computational fluid dynamics flow-solver code
NASA Technical Reports Server (NTRS)
Williams, Anthony D.
1988-01-01
Researchers at NASA Lewis are currently developing an 'intelligent' interface to aid in the development and use of large, computational fluid dynamics flow-solver codes for studying the internal fluid behavior of aerospace propulsion systems. This paper discusses the requirements, design, and implementation of an intelligent interface to Proteus, a general purpose, 3-D, Navier-Stokes flow solver. The interface is called PROTAIS to denote its introduction of artificial intelligence (AI) concepts to the Proteus code.
'Fluid Dynamics,' mixed media by Tina York depicts fluid dynamics studies at the Ames Research
NASA Technical Reports Server (NTRS)
2001-01-01
'Fluid Dynamics,' mixed media by Tina York depicts fluid dynamics studies at the Ames Research Center. The purpose of such studies is to learn more about what happens to an object when it encounters the friction of atmospheric resistence (such as a plane encountering resistance as it speeds through the air). used in Ames 60 year history by Glenn Bugos NASA SP-4314
NASA Astrophysics Data System (ADS)
Awatsuji, Yasuhiro; Xia, Peng; Wang, Yexin; Matoba, Osamu
2016-03-01
Digital holography is a technique of 3D measurement of object. The technique uses an image sensor to record the interference fringe image containing the complex amplitude of object, and numerically reconstructs the complex amplitude by computer. Parallel phase-shifting digital holography is capable of accurate 3D measurement of dynamic object. This is because this technique can reconstruct the complex amplitude of object, on which the undesired images are not superimposed, form a single hologram. The undesired images are the non-diffraction wave and the conjugate image which are associated with holography. In parallel phase-shifting digital holography, a hologram, whose phase of the reference wave is spatially and periodically shifted every other pixel, is recorded to obtain complex amplitude of object by single-shot exposure. The recorded hologram is decomposed into multiple holograms required for phase-shifting digital holography. The complex amplitude of the object is free from the undesired images is reconstructed from the multiple holograms. To validate parallel phase-shifting digital holography, a high-speed parallel phase-shifting digital holography system was constructed. The system consists of a Mach-Zehnder interferometer, a continuous-wave laser, and a high-speed polarization imaging camera. Phase motion picture of dynamic air flow sprayed from a nozzle was recorded at 180,000 frames per second (FPS) have been recorded by the system. Also phase motion picture of dynamic air induced by discharge between two electrodes has been recorded at 1,000,000 FPS, when high voltage was applied between the electrodes.
3D Dynamic Rupture Simulations Across Interacting Faults: the Mw7.0, 2010, Haiti Earthquake
NASA Astrophysics Data System (ADS)
Douilly, R.; Aochi, H.; Calais, E.; Freed, A. M.; Aagaard, B.
2014-12-01
The mechanisms controlling rupture propagation between fault segments during an earthquake are key to the hazard posed by fault systems. Rupture initiation on a fault segment sometimes transfers to a larger fault, resulting in a significant event (e.g.i, 2002 M7.9Denali and 2010 M7.1 Darfield earthquakes). In other cases rupture is constrained to the initial segment and does not transfer to nearby faults, resulting in events of moderate magnitude. This is the case of the 1989 M6.9 Loma Prieta and 2010 M7.0 Haiti earthquakes which initiated on reverse faults abutting against a major strike-slip plate boundary fault but did not propagate onto it. Here we investigatethe rupture dynamics of the Haiti earthquake, seeking to understand why rupture propagated across two segments of the Léogâne fault but did not propagate to the adjacenent Enriquillo Plantain Garden Fault, the major 200 km long plate boundary fault cutting through southern Haiti. We use a Finite Element Model to simulate the nucleation and propagation of rupture on the Léogâne fault, varying friction and background stress to determine the parameter set that best explains the observed earthquake sequence. The best-fit simulation is in remarkable agreement with several finite fault inversions and predicts ground displacement in very good agreement with geodetic and geological observations. The two slip patches inferred from finite-fault inversions are explained by the successive rupture of two fault segments oriented favorably with respect to the rupture propagation, while the geometry of the Enriquillo fault did not allow shear stress to reach failure. Although our simulation results replicate well the ground deformation consistent with the geodetic surface observation but convolving the ground motion with the soil amplification from the microzonation study will correctly account for the heterogeneity of the PGA throughout the rupture area.
Fluid Dynamics in Sucker Rod Pumps
Cutler, R.P.; Mansure, A.J.
1999-01-14
Sucker rod pumps are installed in approximately 90% of all oil wells in the U.S. Although they have been widely used for decades, there are many issues regarding the fluid dynamics of the pump that have not been fully investigated. A project was conducted at Sandia National Laboratories to develop unimproved understanding of the fluid dynamics inside a sucker rod pump. A mathematical flow model was developed to predict pressures in any pump component or an entire pump under single-phase fluid and pumping conditions. Laboratory flow tests were conducted on instrumented individual pump components and on a complete pump to verify and refine the model. The mathematical model was then converted to a Visual Basic program to allow easy input of fluid, geometry and pump parameters and to generate output plots. Examples of issues affecting pump performance investigated with the model include the effects of viscosity, surface roughness, valve design details, plunger and valve pressure differentials, and pumping rate.
NASA Astrophysics Data System (ADS)
Ayers, J.; Owens, C. T.; Liu, K. C.; Swenson, E.; Ghoshal, A.; Weiss, V.
2013-01-01
The application of guided waves to interrogate remote areas of structural components has been researched extensively in characterizing damage. However, there exists a sparsity of work in using piezoelectric transducer-generated guided waves as a method of assessing stress intensity factors (SIF). This quantitative information enables accurate estimation of the remaining life of metallic structures exhibiting cracks, such as military and commercial transport vehicles. The proposed full wavefield approach, based on 3D laser vibrometry and piezoelectric transducer-generated guided waves, provides a practical means for estimation of dynamic stress intensity factors (DSIF) through local strain energy mapping via the J-integral. Strain energies and traction vectors can be conveniently estimated from wavefield data recorded using 3D laser vibrometry, through interpolation and subsequent spatial differentiation of the response field. Upon estimation of the Jintegral, it is possible to obtain the corresponding DSIF terms. For this study, the experimental test matrix consists of aluminum plates with manufactured defects representing canonical elliptical crack geometries under uniaxial tension that are excited by surface mounted piezoelectric actuators. The defects' major to minor axes ratios vary from unity to approximately 133. Finite element simulations are compared to experimental results and the relative magnitudes of the J-integrals are examined.
Knutsen, Ashleen R; Borkowski, Sean L; Ebramzadeh, Edward; Flanagan, Colleen L; Hollister, Scott J; Sangiorgio, Sophia N
2015-09-01
Recently, as an alternative to metal spinal fusion cages, 3D printed bioresorbable materials have been explored; however, the static and fatigue properties of these novel cages are not well known. Unfortunately, current ASTM testing standards used to determine these properties were designed prior to the advent of bioresorbable materials for cages. Therefore, the applicability of these standards for bioresorbable materials is unknown. In this study, an image-based topology and a conventional 3D printed bioresorbable poly(ε)-caprolactone (PCL) cervical cage design were tested in compression, compression-shear, and torsion, to establish their static and fatigue properties. Difficulties were in fact identified in establishing failure criteria and in particular determining compressive failure load. Given these limitations, under static loads, both designs withstood loads of over 650 N in compression, 395 N in compression-shear, and 0.25 Nm in torsion, prior to yielding. Under dynamic testing, both designs withstood 5 million (5M) cycles of compression at 125% of their respective yield forces. Geometry significantly affected both the static and fatigue properties of the cages. The measured compressive yield loads fall within the reported physiological ranges; consequently, these PCL bioresorbable cages would likely require supplemental fixation. Most importantly, supplemental testing methods may be necessary beyond the current ASTM standards, to provide more accurate and reliable results, ultimately improving preclinical evaluation of these devices. PMID:26072198
Knutsen, Ashleen R; Borkowski, Sean L; Ebramzadeh, Edward; Flanagan, Colleen L; Hollister, Scott J; Sangiorgio, Sophia N
2015-09-01
Recently, as an alternative to metal spinal fusion cages, 3D printed bioresorbable materials have been explored; however, the static and fatigue properties of these novel cages are not well known. Unfortunately, current ASTM testing standards used to determine these properties were designed prior to the advent of bioresorbable materials for cages. Therefore, the applicability of these standards for bioresorbable materials is unknown. In this study, an image-based topology and a conventional 3D printed bioresorbable poly(ε)-caprolactone (PCL) cervical cage design were tested in compression, compression-shear, and torsion, to establish their static and fatigue properties. Difficulties were in fact identified in establishing failure criteria and in particular determining compressive failure load. Given these limitations, under static loads, both designs withstood loads of over 650 N in compression, 395 N in compression-shear, and 0.25 Nm in torsion, prior to yielding. Under dynamic testing, both designs withstood 5 million (5M) cycles of compression at 125% of their respective yield forces. Geometry significantly affected both the static and fatigue properties of the cages. The measured compressive yield loads fall within the reported physiological ranges; consequently, these PCL bioresorbable cages would likely require supplemental fixation. Most importantly, supplemental testing methods may be necessary beyond the current ASTM standards, to provide more accurate and reliable results, ultimately improving preclinical evaluation of these devices.
Knutsen, Ashleen R.; Borkowski, Sean L.; Ebramzadeh, Edward; Flanagan, Colleen L.; Hollister, Scott J.; Sangiorgio, Sophia N.
2015-01-01
Recently, as an alternative to metal spinal fusion cages, 3D printed bioresorbable materials have been explored; however, the static and fatigue properties of these novel cages are not well known. Unfortunately, current ASTM testing standards used to determine these properties were designed prior to the advent of bioresorbable materials for cages. Therefore, the applicability of these standards for bioresorbable materials is unknown. In this study, an image-based topology and a conventional 3D printed bioresorbable poly(ε)-caprolactone (PCL) cervical cage design were tested in compression, compression-shear, and torsion, to establish their static and fatigue properties. Difficulties were in fact identified in establishing failure criteria and in particular determining compressive failure load. Given these limitations, under static loads, both designs withstood loads of over 650N in compression, 395N in compression-shear, and 0.25Nm in torsion, prior to yielding. Under dynamic testing, both designs withstood 5 million (5M) cycles of compression at 125% of their respective yield forces. Geometry significantly affected both the static and fatigue properties of the cages. The measured compressive yield loads fall within the reported physiological ranges; consequently, these PCL bioresorbable cages would likely require supplemental fixation. Most importantly, supplemental testing methods may be necessary beyond the current ASTM standards, to provide more accurate and reliable results, ultimately improving preclinical evaluation of these devices. PMID:26072198
Benchmarking computational fluid dynamics models for lava flow simulation
NASA Astrophysics Data System (ADS)
Dietterich, Hannah; Lev, Einat; Chen, Jiangzhi
2016-04-01
Numerical simulations of lava flow emplacement are valuable for assessing lava flow hazards, forecasting active flows, interpreting past eruptions, and understanding the controls on lava flow behavior. Existing lava flow models vary in simplifying assumptions, physics, dimensionality, and the degree to which they have been validated against analytical solutions, experiments, and natural observations. In order to assess existing models and guide the development of new codes, we conduct a benchmarking study of computational fluid dynamics models for lava flow emplacement, including VolcFlow, OpenFOAM, FLOW-3D, and COMSOL. Using the new benchmark scenarios defined in Cordonnier et al. (Geol Soc SP, 2015) as a guide, we model viscous, cooling, and solidifying flows over horizontal and sloping surfaces, topographic obstacles, and digital elevation models of natural topography. We compare model results to analytical theory, analogue and molten basalt experiments, and measurements from natural lava flows. Overall, the models accurately simulate viscous flow with some variability in flow thickness where flows intersect obstacles. OpenFOAM, COMSOL, and FLOW-3D can each reproduce experimental measurements of cooling viscous flows, and FLOW-3D simulations with temperature-dependent rheology match results from molten basalt experiments. We can apply these models to reconstruct past lava flows in Hawai'i and Saudi Arabia using parameters assembled from morphology, textural analysis, and eruption observations as natural test cases. Our study highlights the strengths and weaknesses of each code, including accuracy and computational costs, and provides insights regarding code selection.
NASA Astrophysics Data System (ADS)
Lin, Chia-Wen; Jang, Jiin-Yuh
2005-05-01
Three-dimensional laminar fluid flow and heat transfer over a four-row plate-fin and tube heat exchanger with electrohydrodynamic (EHD) wire electrodes are studied numerically. The effects of different electrode arrangements (square and diagonal), tube pitch arrangements (in-line and staggered) and applied voltage (VE=0-16 kV) are investigated in detail for the Reynolds number range (based on the fin spacing and frontal velocity) ranging from 100 to 1,000. It is found that the EHD enhancement is more effective for lower Re and higher applied voltage. The case of staggered tube pitch with square wire electrode arrangement gives the best heat transfer augmentation. For VE=16 kV and Re = 100, this study identifies a maximum improvement of 218% in the average Nusselt number and a reduction in fin area of 56% as compared that without EHD enhancement.
Chaotic dynamics in dense fluids
Posch, H.A.; Hoover, W.G.
1987-09-01
We present calculations of the full spectra of Lyapunov exponents for 8- and 32-particle systems with periodic boundary conditions and interacting with the repulsive part of a Lennard-Jones potential both in equilibrium and nonequilibrium steady states. Lyapunov characteristic exponents lambda/sub n/ describe the mean exponential rates of divergence and convergence of neighbouring trajectories in phase-space. They are useful in characterizing the stochastic properties of a dynamical system. A new algorithm for their calculation is presented which incorporates ideas from control theory and constraint nonequilibrium molecular dynamics. 4 refs., 1 fig.
Variational principles for stochastic fluid dynamics
Holm, Darryl D.
2015-01-01
This paper derives stochastic partial differential equations (SPDEs) for fluid dynamics from a stochastic variational principle (SVP). The paper proceeds by taking variations in the SVP to derive stochastic Stratonovich fluid equations; writing their Itô representation; and then investigating the properties of these stochastic fluid models in comparison with each other, and with the corresponding deterministic fluid models. The circulation properties of the stochastic Stratonovich fluid equations are found to closely mimic those of the deterministic ideal fluid models. As with deterministic ideal flows, motion along the stochastic Stratonovich paths also preserves the helicity of the vortex field lines in incompressible stochastic flows. However, these Stratonovich properties are not apparent in the equivalent Itô representation, because they are disguised by the quadratic covariation drift term arising in the Stratonovich to Itô transformation. This term is a geometric generalization of the quadratic covariation drift term already found for scalar densities in Stratonovich's famous 1966 paper. The paper also derives motion equations for two examples of stochastic geophysical fluid dynamics; namely, the Euler–Boussinesq and quasi-geostropic approximations. PMID:27547083
Using Parameters of Dynamic Pulse Function for 3d Modeling in LOD3 Based on Random Textures
NASA Astrophysics Data System (ADS)
Alizadehashrafi, B.
2015-12-01
The pulse function (PF) is a technique based on procedural preprocessing system to generate a computerized virtual photo of the façade with in a fixed size square(Alizadehashrafi et al., 2009, Musliman et al., 2010). Dynamic Pulse Function (DPF) is an enhanced version of PF which can create the final photo, proportional to real geometry. This can avoid distortion while projecting the computerized photo on the generated 3D model(Alizadehashrafi and Rahman, 2013). The challenging issue that might be handled for having 3D model in LoD3 rather than LOD2, is the final aim that have been achieved in this paper. In the technique based DPF the geometries of the windows and doors are saved in an XML file schema which does not have any connections with the 3D model in LoD2 and CityGML format. In this research the parameters of Dynamic Pulse Functions are utilized via Ruby programming language in SketchUp Trimble to generate (exact position and deepness) the windows and doors automatically in LoD3 based on the same concept of DPF. The advantage of this technique is automatic generation of huge number of similar geometries e.g. windows by utilizing parameters of DPF along with defining entities and window layers. In case of converting the SKP file to CityGML via FME software or CityGML plugins the 3D model contains the semantic database about the entities and window layers which can connect the CityGML to MySQL(Alizadehashrafi and Baig, 2014). The concept behind DPF, is to use logical operations to project the texture on the background image which is dynamically proportional to real geometry. The process of projection is based on two vertical and horizontal dynamic pulses starting from upper-left corner of the background wall in down and right directions respectively based on image coordinate system. The logical one/zero on the intersections of two vertical and horizontal dynamic pulses projects/does not project the texture on the background image. It is possible to define
Using Parameters of Dynamic Pulse Function for 3d Modeling in LOD3 Based on Random Textures
NASA Astrophysics Data System (ADS)
Alizadehashrafi, B.
2015-12-01
The pulse function (PF) is a technique based on procedural preprocessing system to generate a computerized virtual photo of the façade with in a fixed size square(Alizadehashrafi et al., 2009, Musliman et al., 2010). Dynamic Pulse Function (DPF) is an enhanced version of PF which can create the final photo, proportional to real geometry. This can avoid distortion while projecting the computerized photo on the generated 3D model(Alizadehashrafi and Rahman, 2013). The challenging issue that might be handled for having 3D model in LoD3 rather than LOD2, is the final aim that have been achieved in this paper. In the technique based DPF the geometries of the windows and doors are saved in an XML file schema which does not have any connections with the 3D model in LoD2 and CityGML format. In this research the parameters of Dynamic Pulse Functions are utilized via Ruby programming language in SketchUp Trimble to generate (exact position and deepness) the windows and doors automatically in LoD3 based on the same concept of DPF. The advantage of this technique is automatic generation of huge number of similar geometries e.g. windows by utilizing parameters of DPF along with defining entities and window layers. In case of converting the SKP file to CityGML via FME software or CityGML plugins the 3D model contains the semantic database about the entities and window layers which can connect the CityGML to MySQL(Alizadehashrafi and Baig, 2014). The concept behind DPF, is to use logical operations to project the texture on the background image which is dynamically proportional to real geometry. The process of projection is based on two vertical and horizontal dynamic pulses starting from upper-left corner of the background wall in down and right directions respectively based on image coordinate system. The logical one/zero on the intersections of two vertical and horizontal dynamic pulses projects/does not project the texture on the background image. It is possible to define
NASA Astrophysics Data System (ADS)
Hansen, U.
Plumes form as instabilities from thermal boundary layers of convecting systems.The shape, the size and the temporal evolution of plumes is strongly influenced by the vis- cosity of the material. Employing a numerical scheme the evolution of plumes in fluids with strong temperature and temperature-pressure dependent viscosity has been stud- ied. The strong dependence of viscosity on temperature leads to a pulse-like evolution of the plumes.Pulses of hot material rise episodically through the pre-established low viscosity channels. In a later stage the plumes generate extended network-like struc- tures in the thermal boundary layers. Pressure dependence of the viscosity leads to a significant cooling of the plumes.Furthe a fragmentation of one plume into several smaller ones is commonly observed. While internal convection takes place within the plume head, only little entrainment of material is observed.
NASA Astrophysics Data System (ADS)
Pusok, Adina E.; Kaus, Boris J. P.; Popov, Anton A.
2016-04-01
Most of the major mountain belts and orogenic plateaus are found within the overlying plate of active or fossil subduction and/or collision zones. Moreover, they evolve differently from one another as the result of specific combinations of surface and mantle processes. These differences arise for several reasons, such as different rheological properties, different amounts of regional isostatic compensation, and different mechanisms by which forces are applied to the convergent plates. Previous 3D geodynamic models of subduction/collision processes have used various rheological approximations, making numerical results difficult to compare, since there is no clear image on the extent of these approximations on the dynamics. Here, we employ the code LaMEM to perform high-resolution long-term 3D simulations of subduction/continental collision in an integrated lithospheric and upper-mantle scale model. We test the effect of rheological approximations on mantle and lithosphere dynamics in a geometrically simplified model setup that resembles a tectonic map of the India-Asia collision zone. We use the "sticky-air" approach to allow for the development of topography and the dynamics of subduction and collision is entirely driven by slab-pull (i.e. "free subduction"). The models exhibit a wide range of behaviours depending on the rheological law employed: from linear to temperature-dependent visco-elasto-plastic rheology that takes into account both diffusion and dislocation creep. For example, we find that slab dynamics varies drastically between end member models: in viscous approximations, slab detachment is slow following a viscous thinning, while for a non-linear visco-elasto-plastic rheology, slab detachment is relatively fast, inducing strong mantle flow in the slab window. We also examine the stress states in the subducting and overriding plates and topography evolution in the upper plate, and we discuss the implications on lithosphere dynamics at convergent margins
Computational fluid dynamics - A personal view
NASA Technical Reports Server (NTRS)
Hussaini, M. Y.
1989-01-01
This paper provides a personal view of computational fluid dynamics. The main theme is divided into two categories - one dealing with algorithms and engineering applications and the other with scientific investigations. The former category may be termed computational aerodynamics, with the objective of providing reliable aerodynamic or engineering predictions. The latter category is essentially basic research, where the algorithmic tools are used to unravel and elucidate fluid-dynamic phenomena hard to obtain in a laboratory. A critique of the numerical solution techniques for both compressible and incompressible flows is included. The discussion on scientific investigations deals in particular with transition and turbulence.
Reduced MHD and Astrophysical Fluid Dynamics
NASA Astrophysics Data System (ADS)
Arter, Wayne
2011-08-01
Recent work has shown a relationship between between the equations of Reduced Magnetohydrodynamics (RMHD), used to model magnetic fusion laboratory experiments, and incompressible magnetoconvection (IMC), employed in the simulation of astrophysical fluid dynamics (AFD), which means that the two systems are mathematically equivalent in certain geometries. Limitations on the modelling of RMHD, which were found over twenty years ago, are reviewed for an AFD audience, together with hitherto unpublished material on the role of finite-time singularities in the discrete equations used to model fluid dynamical systems. Possible implications for turbulence modelling are mentioned.
Comparing the effects of rheology on the dynamics and topography of 3D subduction-collision models
NASA Astrophysics Data System (ADS)
Pusok, Adina E.; Kaus, Boris; Popov, Anton
2015-04-01
Most of the major mountain belts and orogenic plateaus are found within the overlying plate of active or fossil subduction and/or collision zones. It is well known that they evolve differently from one another as the result of specific combinations of surface and mantle processes. The differences among the structures and evolutions of mountain belts arise for several reasons, such as different strengths of materials, different amounts of regional isostatic compensation, and different mechanisms by which forces are applied to the convergence plates. All these possible controlling factors can change with space and time. Of all the mountain belts and orogenic plateaus, the most striking example is the India-Asia collision zone, which gave rise to the Himalayas and the Tibetan Plateau, the largest region of elevated topography and anomalously thick crust on Earth. Understanding the formation and evolution of such a highly elevated region has been the focus of many tectonic and numerical models. While some of these models (i.e. thin sheet model) have successfully illustrated some of the basic physics of continental collision, none can simultaneously represent active processes such as subduction, underthrusting, channel flow or extrusion, for which fully 3D models are required. Here, we employed the 3D code LaMEM to investigate the role that subduction, continental collision and indentation play on lithosphere dynamics at convergent margins, and the implications they have for the Asian tectonics. Our model setup resembles a simplified tectonic map of the India-Asia collision zone and we performed long-term 3D simulations to analyse the dynamics and the conditions under which large topographic plateaus, such as the Tibetan Plateau can form in an integrated lithospheric and upper-mantle scale model. Results of models with linear viscous rheologies show different modes between the oceanic subduction side (continuous subduction, trench retreat and slab roll-back) and the
Users manual for CAFE-3D : a computational fluid dynamics fire code.
Khalil, Imane; Lopez, Carlos; Suo-Anttila, Ahti Jorma
2005-03-01
The Container Analysis Fire Environment (CAFE) computer code has been developed to model all relevant fire physics for predicting the thermal response of massive objects engulfed in large fires. It provides realistic fire thermal boundary conditions for use in design of radioactive material packages and in risk-based transportation studies. The CAFE code can be coupled to commercial finite-element codes such as MSC PATRAN/THERMAL and ANSYS. This coupled system of codes can be used to determine the internal thermal response of finite element models of packages to a range of fire environments. This document is a user manual describing how to use the three-dimensional version of CAFE, as well as a description of CAFE input and output parameters. Since this is a user manual, only a brief theoretical description of the equations and physical models is included.
Fluid Dynamic Verification Experiments on STS-70
NASA Technical Reports Server (NTRS)
Kleis, Stanley J.
1996-01-01
Fluid dynamic experiments were flown on STS-70 as phase two of the engineering evaluation of the first bioreactor Engineering Development Unit (EDU#1). The phase one experiments were comparative cell cultures in identical units on earth and onboard STS-70. In phase two, two types of fluid dynamic experiments were performed. Qualitative comparisons of the basic flow patterns were evaluated with the use of 'dye' streaklines formed from alternate injections of either a mild acid or base solution into the external flow loop that was then perfused into the vessel. The presence of Bromothymol Blue in the fluid then caused color changes from yellow to blue or vice versa, indicating the basic fluid motions. This reversible change could be repeated as desired. In the absence of significant density differences in the fluid, the flow patterns in space should be the same as on earth. Video tape records of the flow patterns for a wide range of operating conditions were obtained. The second type of fluid dynamic experiment was the quantitative evaluation of the trajectories of solid beads of various densities and sizes. The beads were introduced into the vessel and the paths recorded on video tape, with the vessel operated at various rotation rates and flow perfusion rates. Because of space limitations, the video camera was placed as close as possible to the vessel, resulting in significant optical distortion. This report describes the analysis methods to obtain comparisons between the in-flight fluid dynamics and numerical models of the flow field. The methods include optical corrections to the video images and calculation of the bead trajectories for given operating conditions and initial bead locations.
Weiner, Allon; Dahan-Pasternak, Noa; Shimoni, Eyal; Shinder, Vera; von Huth, Palle; Elbaum, Michael; Dzikowski, Ron
2011-07-01
The deadliest form of human malaria is caused by the protozoan parasite Plasmodium falciparum. The complex life cycle of this parasite is associated with tight transcriptional regulation of gene expression. Nuclear positioning and chromatin dynamics may play an important role in regulating P. falciparum virulence genes. We have applied an emerging technique of electron microscopy to construct a 3D model of the parasite nucleus at distinct stages of development within the infected red blood cell. We have followed the distribution of nuclear pores and chromatin throughout the intra-erythrocytic cycle, and have found a striking coupling between the distributions of nuclear pores and chromatin organization. Pore dynamics involve clustering, biogenesis, and division among daughter cells, while chromatin undergoes stage-dependent changes in packaging. Dramatic changes in heterochromatin distribution coincide with a previously identified transition in gene expression and nucleosome positioning during the mid-to-late schizont phase. We also found a correlation between euchromatin positioning at the nuclear envelope and the local distribution of nuclear pores, as well as a dynamic nuclear polarity during schizogony. These results suggest that cyclic patterns in gene expression during parasite development correlate with gross changes in cellular and nuclear architecture.
Börner, Richard; Ehrlich, Nicky; Hohlbein, Johannes; Hübner, Christian G
2016-05-01
Interactions between single molecules profoundly depend on their mutual three-dimensional orientation. Recently, we demonstrated a technique that allows for orientation determination of single dipole emitters using a polarization-resolved distribution of fluorescence into several detection channels. As the method is based on the detection of single photons, it additionally allows for performing fluorescence correlation spectroscopy (FCS) as well as dynamical anisotropy measurements thereby providing access to fast orientational dynamics down to the nanosecond time scale. The 3D orientation is particularly interesting in non-isotropic environments such as lipid membranes, which are of great importance in biology. We used giant unilamellar vesicles (GUVs) labeled with fluorescent dyes down to a single molecule concentration as a model system for both, assessing the robustness of the orientation determination at different timescales and quantifying the associated errors. The vesicles provide a well-defined spherical surface, such that the use of fluorescent lipid dyes (DiO) allows to establish a a wide range of dipole orientations experimentally. To complement our experimental data, we performed Monte Carlo simulations of the rotational dynamics of dipoles incorporated into lipid membranes. Our study offers a comprehensive view on the dye orientation behavior in a lipid membrane with high spatiotemporal resolution representing a six-dimensional fluorescence detection approach. PMID:26972111
Particle dynamics in fluids with random interactions
NASA Astrophysics Data System (ADS)
Shagolsem, Lenin S.; Rabin, Yitzhak
2016-05-01
We study the dynamics of particles in a multi-component 2d Lennard-Jones (LJ) fluid in the limiting case where all the particles are different (APD). The equilibrium properties of this APD system were studied in our earlier work [L. S. Shagolsem et al., J. Chem. Phys. 142, 051104 (2015).]. We use molecular dynamics simulations to investigate the statistical properties of particle trajectories in a temperature range covering both the fluid and the solid-fluid coexistence region. We calculate the mean-square displacement as well as displacement, angle, and waiting time distributions, and compare the results with those for one-component LJ fluid. As temperature is lowered, the dynamics of the APD system becomes increasingly complex, as the intrinsic difference between the particles is amplified by neighborhood identity ordering and by the inhomogeneous character of the solid-fluid coexistence region. The ramifications of our results for the analysis of protein tracking experiments in living cells are discussed.
A study of the variation of physical conditions in the cometary coma based on a 3D multi-fluid model
NASA Astrophysics Data System (ADS)
Shou, Y.; Combi, M. R.; Fougere, N.; Tenishev, V.; Toth, G.; Gombosi, T. I.; Huang, Z.; Jia, X.; Bieler, A. M.; Hansen, K. C.
2015-12-01
Physics-based numerical coma models are desirable whether to interpret the spacecraft observations of the inner coma or to compare with the ground-based observations of the outer coma. One example is Direct Simulation Monte Carlo (DSMC) method, which has been successfully adopted to simulate the coma under various complex conditions. However, for bright comets with large production rates, the time step in DSMC model has to be tiny to accommodate the small mean free path and the high collision frequency. In addition a truly time-variable 3D DSMC model would still be computationally difficult or even impossible under most circumstances. In this work, we develop a multi-neutral-fluid model based on BATS-R-US in the University of Michigan's SWMF (Space Weather Modeling Framework), which can serve as a useful alternative to DSMC methods to compute both the inner and the outer coma and to treat time-variable phenomena. This model treats H2O, OH, H2, O, H and CO2 as separate fluids and each fluid has its own velocity and temperature. But collisional interactions can also couple all fluids together. Collisional interactions tend to decrease the velocity differences and are also able to re-distribute the excess energy deposited by chemical reactions among all species. To compute the momentum and energy transfer caused by such interactions self-consistently, collisions between fluids, whose efficiency is proportional to the densities, are included as well as heating from various chemical reactions. By applying the model to comets with different production rates (i.e. 67P/Churyumov-Gerasimenko, 1P/Halley, etc.), we are able to study how the heating efficiency varies with cometocentric distances and production rates. The preliminary results and comparison are presented and discussed. This work has been partially supported by grant NNX14AG84G from the NASA Planetary Atmospheres Program, and US Rosetta contracts JPL #1266313, JPL #1266314 and JPL #1286489.
Fluid dynamics in porous media with Sailfish
NASA Astrophysics Data System (ADS)
Coelho, Rodrigo C. V.; Neumann, Rodrigo F.
2016-09-01
In this work we show the application of Sailfish to the study of fluid dynamics in porous media. Sailfish is an open-source software based on the lattice-Boltzmann method. This application of computational fluid dynamics is of particular interest to the oil and gas industry and the subject could be a starting point for an undergraduate or graduate student in physics or engineering. We built artificial samples of porous media with different porosities and used Sailfish to simulate the fluid flow through them in order to calculate their permeability and tortuosity. We also present a simple way to obtain the specific superficial area of porous media using Python libraries. To contextualise these concepts, we analyse the applicability of the Kozeny-Carman equation, which is a well-known permeability-porosity relation, to our artificial samples.
The Fluid Dynamics of Competitive Swimming
NASA Astrophysics Data System (ADS)
Wei, Timothy; Mark, Russell; Hutchison, Sean
2014-01-01
Nowhere in sport is performance so dependent on the interaction of the athlete with the surrounding medium than in competitive swimming. As a result, understanding (at least implicitly) and controlling (explicitly) the fluid dynamics of swimming are essential to earning a spot on the medal stand. This is an extremely complex, highly multidisciplinary problem with a broad spectrum of research approaches. This review attempts to provide a historical framework for the fluid dynamics-related aspects of human swimming research, principally conducted roughly over the past five decades, with an emphasis on the past 25 years. The literature is organized below to show a continuous integration of computational and experimental technologies into the sport. Illustrations from the authors' collaborations over a 10-year period, coupling the knowledge and experience of an elite-level coach, a lead biomechanician at USA Swimming, and an experimental fluid dynamicist, are intended to bring relevance and immediacy to the review.
Environmental Fluid Dynamics in Space Capsule
NASA Astrophysics Data System (ADS)
Yin, Zhaohua
Environmental fluid dynamics began to get more and more concern recently because of its effects on indoor air quality and ventilation strategy. Our research is trying to use the tools of Environmental fluid dynamics to investigate the life support system (LSS) for manned space flight, especially for future long-term planetary exploration flight (permanent space station and lunar base, space greenhouse of controlled ecological life support systems (CELSS) etc.). The PIV technique will be adopted to obtain the velocity of the flow field and dyed fluids to capture the temperature field. On the other hand, we will use the commercial software (FLUENT) to numerical simulate the same problem. The results in this work can be used to improve the ventilation efficiency, reduce the energy costs and try to make the air in space capsule less effluvial.
Fluid dynamics in porous media with Sailfish
NASA Astrophysics Data System (ADS)
Coelho, Rodrigo C. V.; Neumann, Rodrigo F.
2016-09-01
In this work we show the application of Sailfish to the study of fluid dynamics in porous media. Sailfish is an open-source software based on the lattice-Boltzmann method. This application of computational fluid dynamics is of particular interest to the oil and gas industry and the subject could be a starting point for an undergraduate or graduate student in physics or engineering. We built artificial samples of porous media with different porosities and used Sailfish to simulate the fluid flow through them in order to calculate their permeability and tortuosity. We also present a simple way to obtain the specific superficial area of porous media using Python libraries. To contextualise these concepts, we analyse the applicability of the Kozeny–Carman equation, which is a well-known permeability–porosity relation, to our artificial samples.
NASA Astrophysics Data System (ADS)
Dong, C.; Bougher, S. W.; Ma, Y.; Toth, G.; Lee, Y.; Nagy, A. F.; Tenishev, V.; Pawlowski, D. J.; Meng, X.; Combi, M. R.
2013-12-01
The study of the solar wind interaction with Mars upper atmosphere/ionosphere has triggered a great of interest in recent years. Among the large number of topics in this research area, the investigation of ion escape fluxes has become increasingly important due to its potential impact on the long-term evolution of Mars atmosphere (e.g., loss of water) over its history. In the present work, we adopt the 3-D Mars cold neutral atmosphere profiles (0~300 km) from the newly developed and validated Mars Global Ionosphere Thermosphere Model (M-GITM) and the 3-D hot oxygen profiles (100km~5RM) from the exosphere Monte Carlo model Adaptive Mesh Particle Simulator (AMPS). We apply these 3-D model outputs fields into the 3-D BATS-R-US Mars multi-fluid MHD model (100km~20RM) that can better simulate the interplay between Mars upper atmosphere and solar wind by considering the dynamics of individual ion species. The multi-fluid model solves separate continuity, momentum and energy equations for each ion species (H+, O+, O2+, CO2+). The M-GITM model together with the AMPS exosphere model take into account the effects of solar cycle and seasonal variations on both cold and hot neutral atmospheres, allowing us to investigate the corresponding effects on the Mars upper atmosphere ion escape by using a one-way coupling approach, i.e., both the M-GITM and AMPS model outputs are used as the inputs for the multi-fluid model and M-GITM is used as input into the AMPS exosphere model. The calculations are carried out for selected cases with different nominal solar wind, solar cycle and crustal field orientation conditions. This work has the potential to provide predictions of ion escape rates for comparison to future data to be returned by the MAVEN primary mission (2014-2016) and thereby improve our understanding of present day escape processes. Acknowledgments: The work presented here was supported by NASA grants NNH10CC04C, NNX09AL26G, NSF grant ATM-0535811.
Nonlinear astrophysical fluid dynamics: the video.
NASA Astrophysics Data System (ADS)
Norman, M. L.
A videotape has been assembled containing animations shown by speakers at the Nonlinear Astrophysical Fluid Dynamics Conference. This videotape forms a useful supplement to the conference proceedings. The videotape is available from the National Center for Supercomputing Applications for the cost of materials (6 for 1/2″tapes; 12.50 for 3/4″tapes) and shipping.
Computational fluid dynamics in oil burner design
Butcher, T.A.
1997-09-01
In Computational Fluid Dynamics, the differential equations which describe flow, heat transfer, and mass transfer are approximately solved using a very laborious numerical procedure. Flows of practical interest to burner designs are always turbulent, adding to the complexity of requiring a turbulence model. This paper presents a model for burner design.
V/STOL aircraft and fluid dynamic
NASA Astrophysics Data System (ADS)
Roberts, L.; Anderson, S. B.
1982-01-01
The impact of military applications on rotorcraft and V/STOL aircraft design with respect to fixed wing aircraft is discussed. The influence of the mission needs on the configurational design of V/STOL aircraft, the implications regarding some problems in fluid dynamics relating to propulsive flows, and their interaction with the aircraft and the ground plane, are summarized.
Dynamics of squeezing fluids: Clapping wet hands
NASA Astrophysics Data System (ADS)
Gart, Sean; Chang, Brian; Slama, Brice; Goodnight, Randy; Um, Soong Ho; Jung, Sunghwan
2013-08-01
Droplets splash around when a fluid volume is quickly compressed. This phenomenon has been observed during common activities such as kids clapping with wet hands. The underlying mechanism involves a fluid volume being compressed vertically between two objects. This compression causes the fluid volume to be ejected radially and thereby generate fluid threads and droplets at a high speed. In this study, we designed and performed laboratory experiments to observe the process of thread and drop formation after a fluid is squeezed. A thicker rim at the outer edge forms and moves after the squeezing, and then becomes unstable and breaks into smaller drops. This process differs from previous well-known examples (i.e., transient crown splashes and continuous water bells) in aspects of transient fluid feeding, expanding rim dynamics, or sparsely distributed drops. We compared experimental measurements with theoretical models over three different stages; early squeezing, intermediate sheet-expansion, and later break-up of the liquid thread. In the earlier stage, the fluid is squeezed and its initial velocity is governed by the lubrication force. The outer rim of the liquid sheet forms curved trajectories due to gravity, inertia, drag, and surface tension. At the late stage, drop spacing set by the initial capillary instability does not change in the course of rim expansion, consequently final ejected droplets are very sparse compared to the size of the rim.
Effects of fluid dynamics on cleaning efficacy of supercritical fluids
Phelps, M.R.; Willcox, W.A.; Silva, L.J.; Butner, R.S.
1993-03-01
Pacific Northwest Laboratory (PNL) and Boeing Aerospace Company are developing a process to clean metal parts using a supercritical solvent. This work is part of an effort to address issues inhibiting the rapid commercialization of Supercritical Fluid Parts Cleaning (SFPC). PNL assembled a SFPC test stand to observe the relationship between the fluid dynamics of the system and the mass transfer of a contaminant from the surface of a contaminated metal coupon into the bulk fluid. The bench-scale test stand consists of a ``Berty`` autoclave modified for these tests and supporting hardware to achieve supercritical fluids parts cleaning. Three separate sets of tests were conducted using supercritical carbon dioxide. For the first two tests, a single stainless steel coupon was cleaned with organic solvents to remove surface residue, doped with a single contaminant, and then cleaned in the SFPC test stand. Contaminants studied were Dow Corning 200 fluid (dimethylpolysiloxane) and Castle/Sybron X-448 High-temperature Oil (a polybutane/mineral oil mixture). A set of 5-minute cleaning runs was conducted for each dopant at various autoclave impeller speeds. Test results from the first two sets of experiments indicate that precision cleaning for difficult-to-remove contaminants can be dramatically improved by introducing and increasing turbulence within the system. Metal coupons that had been previously doped with aircraft oil were used in a third set of tests. The coupons were placed in the SFPC test stand and subjected to different temperatures, pressures, and run times at a constant impeller speed. The cleanliness of each part was measured by Optically Stimulated Electron Emission. The third set of tests show that levels of cleanliness attained with supercritical carbon dioxide compare favorably with solvent and aqueous cleaning levels.
Effects of fluid dynamics on cleaning efficacy of supercritical fluids
Phelps, M.R.; Willcox, W.A.; Silva, L.J.; Butner, R.S.
1993-03-01
Pacific Northwest Laboratory (PNL) and Boeing Aerospace Company are developing a process to clean metal parts using a supercritical solvent. This work is part of an effort to address issues inhibiting the rapid commercialization of Supercritical Fluid Parts Cleaning (SFPC). PNL assembled a SFPC test stand to observe the relationship between the fluid dynamics of the system and the mass transfer of a contaminant from the surface of a contaminated metal coupon into the bulk fluid. The bench-scale test stand consists of a Berty'' autoclave modified for these tests and supporting hardware to achieve supercritical fluids parts cleaning. Three separate sets of tests were conducted using supercritical carbon dioxide. For the first two tests, a single stainless steel coupon was cleaned with organic solvents to remove surface residue, doped with a single contaminant, and then cleaned in the SFPC test stand. Contaminants studied were Dow Corning 200 fluid (dimethylpolysiloxane) and Castle/Sybron X-448 High-temperature Oil (a polybutane/mineral oil mixture). A set of 5-minute cleaning runs was conducted for each dopant at various autoclave impeller speeds. Test results from the first two sets of experiments indicate that precision cleaning for difficult-to-remove contaminants can be dramatically improved by introducing and increasing turbulence within the system. Metal coupons that had been previously doped with aircraft oil were used in a third set of tests. The coupons were placed in the SFPC test stand and subjected to different temperatures, pressures, and run times at a constant impeller speed. The cleanliness of each part was measured by Optically Stimulated Electron Emission. The third set of tests show that levels of cleanliness attained with supercritical carbon dioxide compare favorably with solvent and aqueous cleaning levels.
Larson, Peder E Z; Hu, Simon; Lustig, Michael; Kerr, Adam B; Nelson, Sarah J; Kurhanewicz, John; Pauly, John M; Vigneron, Daniel B
2011-03-01
Hyperpolarized 13C MR spectroscopic imaging can detect not only the uptake of the pre-polarized molecule but also its metabolic products in vivo, thus providing a powerful new method to study cellular metabolism. Imaging the dynamic perfusion and conversion of these metabolites provides additional tissue information but requires methods for efficient hyperpolarization usage and rapid acquisitions. In this work, we have developed a time-resolved 3D MR spectroscopic imaging method for acquiring hyperpolarized 13C data by combining compressed sensing methods for acceleration and multiband excitation pulses to efficiently use the magnetization. This method achieved a 2 sec temporal resolution with full volumetric coverage of a mouse, and metabolites were observed for up to 60 sec following injection of hyperpolarized [1-(13)C]-pyruvate. The compressed sensing acquisition used random phase encode gradient blips to create a novel random undersampling pattern tailored to dynamic MR spectroscopic imaging with sampling incoherency in four (time, frequency, and two spatial) dimensions. The reconstruction was also tailored to dynamic MR spectroscopic imaging by applying a temporal wavelet sparsifying transform to exploit the inherent temporal sparsity. Customized multiband excitation pulses were designed with a lower flip angle for the [1-(13)C]-pyruvate substrate given its higher concentration than its metabolic products ([1-(13)C]-lactate and [1-(13)C]-alanine), thus using less hyperpolarization per excitation. This approach has enabled the monitoring of perfusion and uptake of the pyruvate, and the conversion dynamics to lactate and alanine throughout a volume with high spatial and temporal resolution. PMID:20939089
Larson, Peder E. Z.; Hu, Simon; Lustig, Michael; Kerr, Adam B.; Nelson, Sarah J.; Kurhanewicz, John; Pauly, John M.; Vigneron, Daniel B.
2010-01-01
Hyperpolarized 13C MRSI can detect not only the uptake of the pre-polarized molecule but also its metabolic products in vivo, thus providing a powerful new method to study cellular metabolism. Imaging the dynamic perfusion and conversion of these metabolites provides additional tissue information but requires methods for efficient hyperpolarization usage and rapid acquisitions. In this work, we have developed a time-resolved 3D MRSI method for acquiring hyperpolarized 13C data by combining compressed sensing methods for acceleration and multiband excitation pulses to efficiently use the magnetization. This method achieved a 2 sec temporal resolution with full volumetric coverage of a mouse, and metabolites were observed for up to 60 sec following injection of hyperpolarized [1-13C]-pyruvate. The compressed sensing acquisition used random phase encode gradient blips to create a novel random undersampling pattern tailored to dynamic MRSI with sampling incoherency in four (time, frequency and two spatial) dimensions. The reconstruction was also tailored to dynamic MRSI by applying a temporal wavelet sparsifying transform in order to exploit the inherent temporal sparsity. Customized multiband excitation pulses were designed with a lower flip angle for the [1-13C]-pyruvate substrate given its higher concentration than its metabolic products ([1-13C]-lactate and [1-13C]-alanine), thus using less hyperpolarization per excitation. This approach has enabled the monitoring of perfusion and uptake of the pyruvate, and the conversion dynamics to lactate and alanine throughout a volume with high spatial and temporal resolution. PMID:20939089
Fluid Dynamics of Bubbly Liquids
NASA Technical Reports Server (NTRS)
Tsang, Y. H.; Koch, D. L.; Zenit, R.; Sangani, A.; Kushch, V. I.; Spelt, P. D. M.; Hoffman, M.; Nahra, H.; Fritz, C.; Dolesh, R.
2002-01-01
Experiments have been performed to study the average flow properties of inertially dominated bubbly liquids which may be described by a novel analysis. Bubbles with high Reynolds number and low Weber number may produce a fluid velocity disturbance that can be approximated by a potential flow. We studied the behavior of suspensions of bubbles of about 1.5 mm diameter in vertical and inclined channels. The suspension was produced using a bank of 900 glass capillaries with inner diameter of about 100 microns in a quasi-steady fashion. In addition, salt was added to the suspension to prevent bubble-bubble coalescence. As a result, a nearly monodisperse suspension of bubble was produced. By increasing the inclination angle, we were able to explore an increasing amount of shear to buoyancy motion. A pipe flow experiment with the liquid being recirculated is under construction. This will provide an even larger range of shear to buoyancy motion. We are planning a microgravity experiment in which a bubble suspension is subjected to shearing in a couette cell in the absence of a buoyancy-driven relative motion of the two phases. By employing a single-wire, hot film anemometer, we were able to obtain the liquid velocity fluctuations. The shear stress at the wall was measured using a hot film probe flush mounted on the wall. The gas volume fraction, bubble velocity, and bubble velocity fluctuations were measured using a homemade, dual impedance probe. In addition, we also employed a high-speed camera to obtain the bubble size distribution and bubble shape in a dilute suspension. A rapid decrease in bubble velocity for a dilute bubble suspension is attributed to the effects of bubble-wall collisions. The more gradual decrease of bubble velocity as gas volume fraction increases, due to subsequent hindering of bubble motion, is in qualitative agreement with the predictions of Spelt and Sangani for the effects of potential-flow bubble-bubble interactions on the mean velocity. The
NASA Astrophysics Data System (ADS)
Dick, Jonathan; Tetzlaff, Doerthe; Bradford, John; Soulsby, Chris
2016-04-01
Soil moisture is a fundamental component of the water cycle that influences many hydrological processes, such as flooding, solute transport, biogeochemical processes, and land-atmosphere interactions. The relationship between vegetation and soil moisture is complex and reciprocal. Soil moisture may affect vegetation distribution due to its function as the primary source of water, in turn the structure of vegetation canopies regulate water partitioning into interception, throughfall and steam flow. Such spatial differences in inputs, together with complex patterns of water uptake from distributed root networks can create marked heterogeneity in soil moisture dynamics at small scales. Traditional methods of monitoring soil moisture have revolved around limited point measurements, but improved geophysical techniques have facilitated a trend towards more spatially distributed measurements to help understand this heterogeneity. Here, we present a study using 3D ERT surveys in a 3.2km upland catchment in the Scottish Highlands where increasing afforestation (for climate change adaptation, biofuels and conservation) has the potential to increase interception losses and reduce soil moisture storage. The study combined 3D surveys, traditional point measurements and laboratory analysis of soil cores to assess the plot scale soil moisture dynamics in podzolic soils under forest stands of 15m high Scots pine (Pinus sylvestris) and adjacent non-forest plots dominated by heather (Calluna vulgaris) shrubs (<0.5m high). These dominant species are typical of forest and non-forest vegetation communities the Scottish Highlands. Results showed differences in the soil moisture dynamics under the different vegetation types, with heterogeneous patterns in the forested site mainly correlated with canopy cover and mirroring interception losses. Temporal variability in the forested site was greater, probably due to the interception, and increased evapotranspiration losses relative to the
Choi, Light; Woo Lee, Keun
2016-01-01
Bruton’s tyrosine kinase (BTK) is a cytoplasmic, non-receptor tyrosine kinase which is expressed in most of the hematopoietic cells and plays an important role in many cellular signaling pathways. B cell malignancies are dependent on BCR signaling, thus making BTK an efficient therapeutic target. Over the last few years, significant efforts have been made in order to develop BTK inhibitors to treat B-cell malignancies, and autoimmunity or allergy/hypersensitivity but limited success has been achieved. Here in this study, 3D QSAR pharmacophore models were generated for Btk based on known IC50 values and experimental energy scores with extensive validations. The five features pharmacophore model, Hypo1, includes one hydrogen bond acceptor lipid, one hydrogen bond donor, and three hydrophobic features, which has the highest correlation coefficient (0.98), cost difference (112.87), and low RMS (1.68). It was further validated by the Fisher’s randomization method and test set. The well validated Hypo1 was used as a 3D query to search novel Btk inhibitors with different chemical scaffold using high throughput virtual screening technique. The screened compounds were further sorted by applying ADMET properties, Lipinski’s rule of five and molecular docking studies to refine the retrieved hits. Furthermore, molecular dynamic simulation was employed to study the stability of docked conformation and to investigate the binding interactions in detail. Several important hydrogen bonds with Btk were revealed, which includes the gatekeeper residues Glu475 and Met 477 at the hinge region. Overall, this study suggests that the proposed hits may be more effective inhibitors for cancer and autoimmune therapy. PMID:26784025
Mobile Biplane X-Ray Imaging System for Measuring 3D Dynamic Joint Motion During Overground Gait.
Guan, Shanyuanye; Gray, Hans A; Keynejad, Farzad; Pandy, Marcus G
2016-01-01
Most X-ray fluoroscopy systems are stationary and impose restrictions on the measurement of dynamic joint motion; for example, knee-joint kinematics during gait is usually measured with the subject ambulating on a treadmill. We developed a computer-controlled, mobile, biplane, X-ray fluoroscopy system to track human body movement for high-speed imaging of 3D joint motion during overground gait. A robotic gantry mechanism translates the two X-ray units alongside the subject, tracking and imaging the joint of interest as the subject moves. The main aim of the present study was to determine the accuracy with which the mobile imaging system measures 3D knee-joint kinematics during walking. In vitro experiments were performed to measure the relative positions of the tibia and femur in an intact human cadaver knee and of the tibial and femoral components of a total knee arthroplasty (TKA) implant during simulated overground gait. Accuracy was determined by calculating mean, standard deviation and root-mean-squared errors from differences between kinematic measurements obtained using volumetric models of the bones and TKA components and reference measurements obtained from metal beads embedded in the bones. Measurement accuracy was enhanced by the ability to track and image the joint concurrently. Maximum root-mean-squared errors were 0.33 mm and 0.65° for translations and rotations of the TKA knee and 0.78 mm and 0.77° for translations and rotations of the intact knee, which are comparable to results reported for treadmill walking using stationary biplane systems. System capability for in vivo joint motion measurement was also demonstrated for overground gait.
Vertical Scan (V-SCAN) for 3-D Grid Adaptive Mesh Refinement for an atmospheric Model Dynamical Core
NASA Astrophysics Data System (ADS)
Andronova, N. G.; Vandenberg, D.; Oehmke, R.; Stout, Q. F.; Penner, J. E.
2009-12-01
One of the major building blocks of a rigorous representation of cloud evolution in global atmospheric models is a parallel adaptive grid MPI-based communication library (an Adaptive Blocks for Locally Cartesian Topologies library -- ABLCarT), which manages the block-structured data layout, handles ghost cell updates among neighboring blocks and splits a block as refinements occur. The library has several modules that provide a layer of abstraction for adaptive refinement: blocks, which contain individual cells of user data; shells - the global geometry for the problem, including a sphere, reduced sphere, and now a 3D sphere; a load balancer for placement of blocks onto processors; and a communication support layer which encapsulates all data movement. A major performance concern with adaptive mesh refinement is how to represent calculations that have need to be sequenced in a particular order in a direction, such as calculating integrals along a specific path (e.g. atmospheric pressure or geopotential in the vertical dimension). This concern is compounded if the blocks have varying levels of refinement, or are scattered across different processors, as can be the case in parallel computing. In this paper we describe an implementation in ABLCarT of a vertical scan operation, which allows computing along vertical paths in the correct order across blocks transparent to their resolution and processor location. We test this functionality on a 2D and a 3D advection problem, which tests the performance of the model’s dynamics (transport) and physics (sources and sinks) for different model resolutions needed for inclusion of cloud formation.
Volumetric visualization of 3D data
NASA Technical Reports Server (NTRS)
Russell, Gregory; Miles, Richard
1989-01-01
In recent years, there has been a rapid growth in the ability to obtain detailed data on large complex structures in three dimensions. This development occurred first in the medical field, with CAT (computer aided tomography) scans and now magnetic resonance imaging, and in seismological exploration. With the advances in supercomputing and computational fluid dynamics, and in experimental techniques in fluid dynamics, there is now the ability to produce similar large data fields representing 3D structures and phenomena in these disciplines. These developments have produced a situation in which currently there is access to data which is too complex to be understood using the tools available for data reduction and presentation. Researchers in these areas are becoming limited by their ability to visualize and comprehend the 3D systems they are measuring and simulating.
NASA Astrophysics Data System (ADS)
Thoma, M.; Grosfeld, K.; Barbi, D.; Determann, J.; Goeller, S.; Mayer, C.; Pattyn, F.
2014-01-01
Glaciers and ice caps exhibit currently the largest cryospheric contributions to sea level rise. Modelling the dynamics and mass balance of the major ice sheets is therefore an important issue to investigate the current state and the future response of the cryosphere in response to changing environmental conditions, namely global warming. This requires a powerful, easy-to-use, versatile multi-approximation ice dynamics model. Based on the well-known and established ice sheet model of Pattyn (2003) we develop the modular multi-approximation thermomechanic ice model RIMBAY, in which we improve the original version in several aspects like a shallow ice-shallow shelf coupler and a full 3D-grounding-line migration scheme based on Schoof's (2007) heuristic analytical approach. We summarise the full Stokes equations and several approximations implemented within this model and we describe the different numerical discretisations. The results are cross-validated against previous publications dealing with ice modelling, and some additional artificial set-ups demonstrate the robustness of the different solvers and their internal coupling. RIMBAY is designed for an easy adaption to new scientific issues. Hence, we demonstrate in very different set-ups the applicability and functionality of RIMBAY in Earth system science in general and ice modelling in particular.
Not Available
1984-10-01
STEALTH is a family of computer codes that can be used to calculate a variety of physical processes in which the dynamic behavior of a continuum is involved. The version of STEALTH described in this volume is designed for calculations of fluid-structure interaction. This version of the program consists of a hydrodynamic version of STEALTH which has been coupled to a finite-element code, WHAMSE. STEALTH computes the transient response of the fluid continuum, while WHAMSE computes the transient response of shell and beam structures under external fluid loadings. The coupling between STEALTH and WHAMSE is performed during each cycle or step of a calculation. Separate calculations of fluid response and structure response are avoided, thereby giving a more accurate model of the dynamic coupling between fluid and structure. This volume provides the theoretical background, the finite-difference equations, the finite-element equations, a discussion of several sample problems, a listing of the input decks for the sample problems, a programmer's manual and a description of the input records for the STEALTH/WHAMSE computer program.
Fluid-dynamical model for antisurfactants
NASA Astrophysics Data System (ADS)
Conn, Justin J. A.; Duffy, Brian R.; Pritchard, David; Wilson, Stephen K.; Halling, Peter J.; Sefiane, Khellil
2016-04-01
We construct a fluid-dynamical model for the flow of a solution with a free surface at which surface tension acts. This model can describe both classical surfactants, which decrease the surface tension of the solution relative to that of the pure solvent, and antisurfactants (such as many salts when added to water, and small amounts of water when added to alcohol) which increase it. We demonstrate the utility of the model by considering the linear stability of an infinitely deep layer of initially quiescent fluid. In particular, we predict the occurrence of an instability driven by surface-tension gradients, which occurs for antisurfactant, but not for surfactant, solutions.
Modeling Tools Predict Flow in Fluid Dynamics
NASA Technical Reports Server (NTRS)
2010-01-01
"Because rocket engines operate under extreme temperature and pressure, they present a unique challenge to designers who must test and simulate the technology. To this end, CRAFT Tech Inc., of Pipersville, Pennsylvania, won Small Business Innovation Research (SBIR) contracts from Marshall Space Flight Center to develop software to simulate cryogenic fluid flows and related phenomena. CRAFT Tech enhanced its CRUNCH CFD (computational fluid dynamics) software to simulate phenomena in various liquid propulsion components and systems. Today, both government and industry clients in the aerospace, utilities, and petrochemical industries use the software for analyzing existing systems as well as designing new ones."
Computational Fluid Dynamics Symposium on Aeropropulsion
NASA Technical Reports Server (NTRS)
1991-01-01
Recognizing the considerable advances that have been made in computational fluid dynamics, the Internal Fluid Mechanics Division of NASA Lewis Research Center sponsored this symposium with the objective of providing a forum for exchanging information regarding recent developments in numerical methods, physical and chemical modeling, and applications. This conference publication is a compilation of 4 invited and 34 contributed papers presented in six sessions: algorithms one and two, turbomachinery, turbulence, components application, and combustors. Topics include numerical methods, grid generation, chemically reacting flows, turbulence modeling, inlets, nozzles, and unsteady flows.
Hur, J.; Chun, Y.D.; Lee, J.; Hyun, D.S.
1998-09-01
The distribution of radial force density in brushless permanent magnet DC motor is not uniform in axial direction. The analysis of radial force density has to consider the 3-D shape of teeth and overhand, because the radial force density causes vibration and acts on the surface of teeth inconstantly. For the analysis, a new 3-D equivalent magnetic circuit network method is used to account the rotor movement without remesh. The radial force density is calculated and analyzed by Maxwell stress tensor and discrete Fourier transform (DFT) respectively. The results of 3-D equivalent magnetic circuit method have been compared with the results of 3-D FEM.
Application of a distributed network in computational fluid dynamic simulations
NASA Technical Reports Server (NTRS)
Deshpande, Manish; Feng, Jinzhang; Merkle, Charles L.; Deshpande, Ashish
1994-01-01
A general-purpose 3-D, incompressible Navier-Stokes algorithm is implemented on a network of concurrently operating workstations using parallel virtual machine (PVM) and compared with its performance on a CRAY Y-MP and on an Intel iPSC/860. The problem is relatively computationally intensive, and has a communication structure based primarily on nearest-neighbor communication, making it ideally suited to message passing. Such problems are frequently encountered in computational fluid dynamics (CDF), and their solution is increasingly in demand. The communication structure is explicitly coded in the implementation to fully exploit the regularity in message passing in order to produce a near-optimal solution. Results are presented for various grid sizes using up to eight processors.
Fluid dynamics of forward swimming and turning for jellyfish
NASA Astrophysics Data System (ADS)
Miller, Laura
2012-11-01
Jellyfish propel themselves through the water through periodic contractions of their elastic bells. Some jellyfish, such as the box jellyfish Tripedalia cystophora and the upside down jellyfish Cassiopea xamachana, can perform turns via asymmetric contractions of the bell and by generating asymmetries in the outflow opening of the bell. The fluid dynamics of jellyfish forward propulsion and turning is explored here using the immersed boundary method. The 2D and 3D Navier-Stokes equations are coupled to the motion of a simplified jellyfish represented by an elastic boundary. An adaptive and parallelized version of the immersed boundary method (IBAMR) is used to resolve the detailed structure of the vortex wake. The asymmetric contraction and structure of the jellyfish generates asymmetries in the starting and stopping vortices. This creates a diagonal jet and a net torque acting on the jellyfish.
NASA Astrophysics Data System (ADS)
Payan, A. P.; Paty, C. S.; Retherford, K. D.; Bonfond, B.
2011-12-01
The electrodynamic interaction of Ganymede's mini-magnetosphere with Jupiter's co-rotating magnetospheric plasma has been shown to give rise to strong current systems closing through the moon and its ionosphere as well as through its magnetopause and magnetotail current sheet. This interaction is strongly evidenced by the presence of aurorae at Ganymede and Ganymede's bright auroral footprint in Jupiter's ionosphere. This footprint is located equatorward of the main auroral emissions, at the magnetic longitude of the field line threading Ganymede. The brightness of Ganymede's auroral footprint at Jupiter along with its latitudinal position have been shown to depend on the position of Ganymede relative to the Jovian plasma sheet and on the variations of the current flowing in the Jovian current sheet. Previous studies based on ultraviolet images obtained with the Hubble Space Telescope (HST) have demonstrated that the size of the auroral footprint was not limited to that of the moon alone. Rather, it mapped to a region corresponding to Ganymede's magnetosphere (Grodent et al., 2009). It was recently shown that Ganymede's auroral footprint brightness is characterized by three timescales of variations: a long 5-hour periodic variation, a non-systematic 10-40-minute variation, and a short 100-second quasi-periodic variation (Grodent et al., 2009). As for Ganymede's aurora, observations with the HST revealed longitudinally non-uniform oxygen emissions, with the brightest emissions confined to the geomagnetic latitudes defining the boundaries of the polar caps (Feldman et al., 2000). The goal of the present study is to examine the relationship between the longest and the shortest timescale periodicities of Ganymede's auroral footprint brightness and local processes occurring at Ganymede, using a 3D multi-fluid model. The model allows characterization of the interaction between Ganymede's magnetosphere and the local Jovian plasma environment by tracking the energies and
NASA Astrophysics Data System (ADS)
Simpson, D. G.; Lipatov, A. S.; Sittler, E. C.; Hartle, R. E.; Cooper, J. F.
2013-12-01
Wave-particle interactions play a very important role in the plasma dynamics near Titan: mass loading, excitation of the low-frequency waves and the formation of the particle velocity distribution function, e.g. ring/shell-like distributions, etc. The kinetic approach is important for estimation of the collision processes e.g. a charge exchange. The particle velocity distribution function also plays a key role for understanding the observed particle fluxes. In this report we discuss the ion velocity distribution function dynamics from 3D hybrid modeling. The modeling is based on recent analysis of the Cassini Plasma Spectrometer (CAPS) ion measurements during the TA flyby. In our model the background ions, all pickup ions, and ionospheric ions are considered as particles, whereas the electrons are described as a fluid. Inhomogeneous photoionization, electron-impact ionization and charge exchange are included in our model. The temperatures of the background electrons and pickup electrons were also included into the generalized Ohm's law. We also take into account the collisions between the ions and neutrals. We use Chamberlain profiles for the exosphere's components and include a simple ionosphere model with M=28 ions that were generated inside the ionosphere. The moon is considered as a weakly conducting body. Our modeling shows that interaction between background plasma and pickup ions H+, H2+, CH4+ and N2+ has a more complicated structure than was observed in the T9 flyby and modeling due to the large gyroradius of the background O+ ions [1,2,3,4]. Special attention will be paid to comparing the simulated pickup ion velocity distribution with CAPS TA observations. We also compare our kinetic modeling with other hybrid and MHD modeling of Titan's environment. References [1] Sittler, E.C., et al., Energy Deposition Processes in Titan's Upper Atmosphere and Its Induced Magnetosphere. In: Titan from Cassini-Huygens, Brown, R.H., Lebreton J.P., Waite, J.H., Eds
Allain, Ariane; Chauvot de Beauchêne, Isaure; Langenfeld, Florent; Guarracino, Yann; Laine, Elodie; Tchertanov, Luba
2014-01-01
Allostery is a universal phenomenon that couples the information induced by a local perturbation (effector) in a protein to spatially distant regulated sites. Such an event can be described in terms of a large scale transmission of information (communication) through a dynamic coupling between structurally rigid (minimally frustrated) and plastic (locally frustrated) clusters of residues. To elaborate a rational description of allosteric coupling, we propose an original approach - MOdular NETwork Analysis (MONETA) - based on the analysis of inter-residue dynamical correlations to localize the propagation of both structural and dynamical effects of a perturbation throughout a protein structure. MONETA uses inter-residue cross-correlations and commute times computed from molecular dynamics simulations and a topological description of a protein to build a modular network representation composed of clusters of residues (dynamic segments) linked together by chains of residues (communication pathways). MONETA provides a brand new direct and simple visualization of protein allosteric communication. A GEPHI module implemented in the MONETA package allows the generation of 2D graphs of the communication network. An interactive PyMOL plugin permits drawing of the communication pathways between chosen protein fragments or residues on a 3D representation. MONETA is a powerful tool for on-the-fly display of communication networks in proteins. We applied MONETA for the analysis of communication pathways (i) between the main regulatory fragments of receptors tyrosine kinases (RTKs), KIT and CSF-1R, in the native and mutated states and (ii) in proteins STAT5 (STAT5a and STAT5b) in the phosphorylated and the unphosphorylated forms. The description of the physical support for allosteric coupling by MONETA allowed a comparison of the mechanisms of (a) constitutive activation induced by equivalent mutations in two RTKs and (b) allosteric regulation in the activated and non
NASA Astrophysics Data System (ADS)
Otsuka, H.; Morita, S.; Tanahashi, M.; Ashi, J.; Nagakubo, S.; Fujii, T.
2008-12-01
High resolution 3D seismic survey, "Tokai-oki to Kumano-nada", was conducted for methane hydrate exploration in the eastern Nankai Trough by METI in 2002. Our study focuses on zigzag-shaped specific reflectors on BSR margins, which have been recognized by JOGMEC on the 3D data. We call the reflectors "gFoldback Reflectors (FBRs)"h in this study. From the edge of BSR, the 1st FBR generally extends down to lower formation below the BSR crossing sedimentary horizons. The following FBRs (often the 2nd, sometimes 3rd and above) extend down from the edge of the last FBR forming bellows-like shape. The 1st FBR indicates normal polarity (antiphase of BSR), and the following FBRs change their polarities alternately. FBRs are mostly developed in the well-stratified formation but not in the area of frequent fractures and the area of major lateral lithological change. FBR generally corresponds to lateral seismic facies boundary between BSR distribution area and outside the BSR area. The formation beneath the BSR shows dimmed facies characterized by relatively low amplitude and lack of high frequency components in contrast to outside the BSR area of normal facies. Seismic velocity analysis (JOGMEC, personal communication) suggests that FBRs correspond to velocity boundaries, where the dimmed faceis below the BSR coinsides with relatively low velocity. The polarities of FBRs are also consistent with such velocity changes. Such dimmed facies with low velocity and low amplitude anomaly suggests relation to gas components in the formation water. The lowest FBR does not cross major unconformities, which often exhibit negative polarity suggesting fluid migration from the lower unit. In this case, the lowest FBR which shows negative polarity and reaches the unconformity is to be merged to the negative reflection of the unconformity. In addition, high amplitude layers are sometimes recognized at foldbacks convex to the outside the BSR area. These high amplitude layers probably having
NASA Technical Reports Server (NTRS)
Lipatov, A. S.; Sittler, E. C., Jr.; Hartle, R. E.; Cooper, J. F.; Simpson, D. G.
2011-01-01
In this report we discuss the ion velocity distribution dynamics from the 3D hybrid simulation. In our model the background, pickup, and ionospheric ions are considered as a particles, whereas the electrons are described as a fluid. Inhomogeneous photoionization, electron-impact ionization and charge exchange are included in our model. We also take into account the collisions between the ions and neutrals. The current simulation shows that mass loading by pickup ions H(+); H2(+), CH4(+) and N2(+) is stronger than in the previous simulations when O+ ions are introduced into the background plasma. In our hybrid simulations we use Chamberlain profiles for the atmospheric components. We also include a simple ionosphere model with average mass M = 28 amu ions that were generated inside the ionosphere. The moon is considered as a weakly conducting body. Special attention will be paid to comparing the simulated pickup ion velocity distribution with CAPS T9 observations. Our simulation shows an asymmetry of the ion density distribution and the magnetic field, including the formation of the Alfve n wing-like structures. The simulation also shows that the ring-like velocity distribution for pickup ions relaxes to a Maxwellian core and a shell-like halo.
Guyot, Y; Papantoniou, I; Luyten, F P; Geris, L
2016-02-01
The main challenge in tissue engineering consists in understanding and controlling the growth process of in vitro cultured neotissues toward obtaining functional tissues. Computational models can provide crucial information on appropriate bioreactor and scaffold design but also on the bioprocess environment and culture conditions. In this study, the development of a 3D model using the level set method to capture the growth of a microporous neotissue domain in a dynamic culture environment (perfusion bioreactor) was pursued. In our model, neotissue growth velocity was influenced by scaffold geometry as well as by flow- induced shear stresses. The neotissue was modeled as a homogenous porous medium with a given permeability, and the Brinkman equation was used to calculate the flow profile in both neotissue and void space. Neotissue growth was modeled until the scaffold void volume was filled, thus capturing already established experimental observations, in particular the differences between scaffold filling under different flow regimes. This tool is envisaged as a scaffold shape and bioprocess optimization tool with predictive capacities. It will allow controlling fluid flow during long-term culture, whereby neotissue growth alters flow patterns, in order to provide shear stress profiles and magnitudes across the whole scaffold volume influencing, in turn, the neotissue growth. PMID:26758425
Collective dynamics of sperm in viscoelastic fluid
NASA Astrophysics Data System (ADS)
Tung, Chih-Kuan; Harvey, Benedict B.; Fiore, Alyssa G.; Ardon, Florencia; Suarez, Susan S.; Wu, Mingming
Collective dynamics in biology is an interesting subject for physicists, in part because of its close relations to emergent behaviors in condensed matter, such as phase separation and criticality. However, the emergence of order is often less drastic in systems composed of the living cells, sometimes due to the natural variability among individual organisms. Here, using bull sperm as a model system, we demonstrate that the cells migrate collectively in viscoelastic fluids, exhibiting behavior similar to ``flocking''. This collectiveness is greatly reduced in similarly viscous Newtonian fluids, suggesting that the cell-cell interaction is primarily a result of the elastic property or the memory effect of the fluids, instead of pure hydrodynamic interactions. Unlike bacterial swarming, this collectiveness does not require a change in phenotype of the cells; therefore, it is a better model system for physicists. Supported by NIH grant 1R01HD070038.
NASA Astrophysics Data System (ADS)
Wehrer, Markus; Slater, Lee D.
2015-01-01
Characterization of preferential flow and transport is still a major challenge but may be improved employing noninvasive, tomographic methods. In this study, 3-D time lapse electrical resistivity tomography (ERT) was employed during infiltration on an undisturbed, unsaturated soil core in a laboratory lysimeter. A tracer breakthrough was conducted during transient conditions by applying a series of short-term infiltrations, simulating natural precipitation events. The electrical response was quantitatively validated using data from a multicompartment suction sampler. Water content probes were also installed for ground-truthing of ERT responses. Water content variations associated with an infiltration front dominated the electrical response observed during individual short-term infiltration events, permitting analysis of water content dynamics from ERT data. We found that, instead of the application of an uncertain petrophysical function, shape measures of the electrical conductivity response might be used for constraining hydrological models. Considering tracer breakthroughs, the ERT observed voxel responses from time lapse tomograms at constant water contents in between infiltration events were used to quantitatively characterize the breakthrough curve. Shape parameters of the breakthrough derived from ERT, such as average velocity, were highly correlated with the shape parameters derived from local tracer breakthrough curves observed in the compartments of the suction plate. The study demonstrates that ERT can provide reliable quantitative information on both, tracer breakthroughs and water content variations under the challenging conditions of variable background electrical conductivity of the pore solution and non steady-state infiltration.
Schleich, Jean-Marc; Dillenseger, Jean-Louis; Houyel, Lucile; Almange, Claude; Anderson, Robert H.
2009-01-01
Background Learning embryology remains difficult, since it requires understanding of many complex phenomena. The temporal evolution of developmental events has classically been illustrated using cartoons, which create difficulty in linking spatial and temporal aspects, such correlation being the keystone of descriptive embryology. Methods We synthesized the bibliographic data from recent studies of atrial septal development. On the basis of this synthesis, consensus on the stages of atrial septation as seen in the human heart has been reached by a group of experts in cardiac embryology and paediatric cardiology. This has permitted the preparation of three-dimensional (3-D) computer graphic objects for the anatomical components involved in the different stages of normal human atrial septation. Results We have provided a virtual guide to the process of normal atrial septation, the animation providing an appreciation of the temporal and morphologic events necessary to separate the systemic and pulmonary venous returns. Conclusion We have shown that our animations of normal human atrial septation increase significantly the teaching of the complex developmental processes involved, and provide a new dynamic for the process of learning. PMID:19363807
3D-QSAR, molecular docking and molecular dynamics studies of a series of RORγt inhibitors.
Wang, Fangfang; Yang, Wei; Shi, Yonghui; Le, Guowei
2015-09-01
The discovery of clinically relevant inhibitors of retinoic acid receptor-related orphan receptor-gamma-t (RORγt) for autoimmune diseases therapy has proven to be a challenging task. In the present work, to find out the structural features required for the inhibitory activity, we show for the first time a three-dimensional quantitative structure-activity relationship (3D-QSAR), molecular docking and molecular dynamics (MD) simulations for a series of novel thiazole/thiophene ketone amides with inhibitory activity at the RORγt receptor. The optimum CoMFA and CoMSIA models, derived from ligand-based superimposition I, exhibit leave-one-out cross-validated correlation coefficient (R(2)cv) of .859 and .805, respectively. Furthermore, the external predictive abilities of the models were evaluated by a test set, producing the predicted correlation coefficient (R(2)pred) of .7317 and .7097, respectively. In addition, molecular docking analysis was applied to explore the binding modes between the inhibitors and the receptor. MD simulation and MM/PBSA method were also employed to study the stability and rationality of the derived conformations, and the binding free energies in detail. The QSAR models and the results of molecular docking, MD simulation, binding free energies corroborate well with each other and further provide insights regarding the development of novel RORγt inhibitors with better activity.
NASA Astrophysics Data System (ADS)
Tobon-Gomez, C.; Butakoff, C.; Ordas, S.; Aguade, S.; Frangi, A. F.
2007-03-01
Over the course of the last two decades, myocardial perfusion with Single Photon Emission Computed Tomography (SPECT) has emerged as an established and well-validated method for assessing myocardial ischemia, viability, and function. Gated-SPECT imaging integrates traditional perfusion information along with global left ventricular function. Despite of these advantages, inherent limitations of SPECT imaging yield a challenging segmentation problem, since an error of only one voxel along the chamber surface may generate a huge difference in volume calculation. In previous works we implemented a 3-D statistical model-based algorithm for Left Ventricle (LV) segmentation of in dynamic perfusion SPECT studies. The present work evaluates the relevance of training a different Active Shape Model (ASM) for each frame of the gated SPECT imaging acquisition in terms of their subsequent segmentation accuracy. Models are subsequently employed to segment the LV cavity of gated SPECT studies of a virtual population. The evaluation is accomplished by comparing point-to-surface (P2S) and volume errors, both against a proper Gold Standard. The dataset comprised 40 voxel phantoms (NCAT, Johns Hopkins, University of of North Carolina). Monte-Carlo simulations were generated with SIMIND (Lund University) and reconstructed to tomographic slices with ASPIRE (University of Michigan).
Use of magnetic micro-cantilevers to study the dynamics of 3D engineered smooth muscle constructs
NASA Astrophysics Data System (ADS)
Liu, Alan; Zhao, Ruogang; Copeland, Craig; Chen, Christopher; Reich, Daniel
2013-03-01
The normal and pathological response of arterial tissue to mechanical stimulus sheds important light on such conditions as atherosclerosis and hypertension. While most previous methods of determining the biomechanical properties of arteries have relied on excised tissue, we have devised a system that enables the growth and in situ application of forces to arrays of stable suspended microtissues consisting of arterial smooth muscle cells (SMCs). Briefly, this magnetic microtissue tester system consists of arrays of pairs of elastomeric magnetically actuated micro-cantilevers between which SMC-infused 3D collagen gels self-assemble and remodel into aligned microtissue constructs. These devices allow us to simultaneously apply force and track stress-strain relationships of multiple microtissues per substrate. We have studied the dilatory capacity and subsequent response of the tissues and find that the resulting stress-strain curves show viscoelastic behavior as well as a linear dynamic recovery. These results provide a foundation for elucidating the mechanical behavior of this novel model system as well as further experiments that simulate pathological conditions. Supported in part by NIH grant HL090747.
Schleich, Jean-Marc; Dillenseger, Jean-Louis; Houyel, Lucile; Almange, Claude; Anderson, Robert H
2009-01-01
Learning embryology remains difficult, since it requires understanding of many complex phenomena. The temporal evolution of developmental events has classically been illustrated using cartoons, which create difficulty in linking spatial and temporal aspects, such correlation being the keystone of descriptive embryology. We synthesized the bibliographic data from recent studies of atrial septal development. On the basis of this synthesis, consensus on the stages of atrial septation as seen in the human heart has been reached by a group of experts in cardiac embryology and pediatric cardiology. This has permitted the preparation of three-dimensional (3D) computer graphic objects for the anatomical components involved in the different stages of normal human atrial septation. We have provided a virtual guide to the process of normal atrial septation, the animation providing an appreciation of the temporal and morphologic events necessary to separate the systemic and pulmonary venous returns. We have shown that our animations of normal human atrial septation increase significantly the teaching of the complex developmental processes involved, and provide a new dynamic for the process of learning. PMID:19363807
A 3D hp-Discontinuous Galerkin Method: Revisiting the M7.3 Landers Earthquake Dynamics
NASA Astrophysics Data System (ADS)
Tago, J.; Cruz-Atienza, V. M.; Virieux, J.; Etienne, V.; Sanchez-Sesma, F. J.
2011-12-01
Reliable dynamic source models should account of both fault geometry and heterogeneities in the surrounding medium. In this work we introduce a novel numerical method for modeling the dynamic rupture based on a 3D hp-Discontinuous Galerkin (DG) scheme. Our method is derived from the scheme proposed by Benjemaa et al. (2009), which is based on a Finite Volume (FV) approach. Migrating from such approach to the hp-Discontinuous Galerkin philosophy is somehow straightforward since the FV method can be seen as the DG method with its lowest order or approximation (i.e. P0 element). We present a novel approach for treating dynamic rupture boundary conditions using an hp-Discontinuous Galerkin method for unstructured tetrahedral meshes. Although the theory we have developed holds for fault elements with arbitrary order, we show that second order (P2) elements yield a very good convergence. Since the DG method does not impose continuity between elements, our strategy consists in the way we compute the fluxes across the fault elements. During rupture propagation, the fluxes in the elements where the shear traction overcomes the fault strength are such that continuity of every wavefield is imposed except for the tangential fault velocities, while in the unbroken elements tangential continuity is also imposed. Because the fault nodes of a given element are coupled through the Mass and Flux matrices, when a fault node breaks we impose the shear traction on that node and need to recompute the values throughout the rest, to avoid any violation of the friction law throughout the element. This procedure repeats itself iteratively following a predictor-corrector scheme for a given time step until the element solutions stabilize. We point out that our scheme for the fault fluxes in the case of P0 elements is exactly the same as the one proposed by Benjemaa et al. who compute them through energy balance considerations. To verify our mathematical and computational model we have solved
Modelling of river plume dynamics in Öre estuary (Baltic Sea) with Telemac-3D hydrodynamic model
NASA Astrophysics Data System (ADS)
Sokolov, Alexander
2016-04-01
The main property of river plumes is their buoyancy, fresh water discharged by rivers is less dense than the receiving, saline waters. To study the processes of plume formation in case of river discharge into a brackish estuary where salinity is low (3.5 - 5 psu) a three dimensional hydrodynamic model was applied to the Öre estuary in the Baltic Sea. This estuary is a small fjord-like bay in the north part of the Baltic Sea. Size of the bay is about 8 by 8 km with maximum depth of 35 metres. River Öre has a small average freshwater discharge of 35 m3/s. But in spring during snowmelt the discharge can be many times higher. For example, in April 2015 the discharge increased from 8 m3/s to 160 m3/s in 18 days. To study river plume dynamics a finite element based three dimensional baroclinic model TELEMAC - 3D is used. The TELEMAC modelling suite is developed by the National Laboratory of Hydraulics and Environment (LNHE) of Electricité de France (EDF). Modelling domain was approximated by an unstructured mesh with element size varies from 50 to 500 m. In vertical direction a sigma-coordinate with 20 layers was used. Open sea boundary conditions were obtained from the Baltic Sea model HIROMB-BOOS using COPERNICUS marine environment monitoring service. Comparison of modelling results with observations obtained by BONUS COCOA project's field campaign in Öre estuary in 2015 shows that the model plausible simulate river plume dynamics. Modelling of age of freshwater is also discussed. This work resulted from the BONUS COCOA project was supported by BONUS (Art 185), funded jointly by the EU and the Swedish Research Council Formas.
The fluid dynamics of human birth
NASA Astrophysics Data System (ADS)
Lehn, Andrea; Leftwich, Megan C.
2012-11-01
This study investigates the fluid dynamics associated with the human birth process. Specifically, we investigate the role of the viscosity of the amniotic fluid in transferring force from the contracting uterus to the fetus during delivery. This experimental work uses an approximate uterus and dilated cervix-fabricated with liquid latex-filled with a fluid of known viscosity and an oblong solid fetus. The force required to extract the fetus is recorded for several values of amniotic viscosity. The study looks at both pull-out force values (where the fetus is pulled from outside the uterus) and push-out force values (where pressure in the experimental uterus is used to remove the fetus). In addition to the viscosity study, we also investigate the increased force required to deliver an offset fetus by tilting the major axis of the oblong fetus and repeating the pull-and push-out experiments. This study will provide knowledge about the fundamental fluid dynamic processes involved in human birth.
Fluid Dynamics in Sucker Rod Pumps
Cutler, Robert P.; Mansure, Arthur J.
1999-06-01
Sucker rod pumps are installed in approximately 90% of all oil wells in the U.S. Although they have been widely used for decades, there are many issues regarding the fluid dynamics of the pump that have not been filly investigated. A project was conducted at Sandia National Laboratories to develop an improved understanding of the fluid dynamics inside a sucker rod pump. A mathematical flow model was developed to predict pressures in any pump component or an entire pump under single-phase fluid and pumping conditions. Laboratory flow tests were conducted on instrumented individual pump components and on a complete pump to verifi and refine the model. The mathematical model was then converted to a Visual Basic program to allow easy input of fluid, geometry and pump parameters and to generate output plots. Examples of issues affecting pump performance investigated with the model include the effects of viscosity, surface roughness, valve design details, plunger and valve pressure differentials, and pumping rate.
Glassy dynamics in a confined monatomic fluid
NASA Astrophysics Data System (ADS)
Krishnan, S. H.; Ayappa, K. G.
2012-07-01
Molecular dynamic simulations of a strongly inhomogeneous system reveals that a single-component soft-sphere fluid can behave as a fragile glass former due to confinement. The self-intermediate scattering function, Fs(k,t), of a Lennard-Jones fluid confined in slit-shaped pores, which can accomodate two to four fluid layers, exhibits a two-step relaxation at moderate temperatures. The mean-squared displacement data are found to follow time-temperature superposition and both the self-diffusivity and late α relaxation times exhibit power-law divergences as the fluid is cooled. The system possesses a crossover temperature and follows the scalings of mode coupling theory for the glass transition. The temperature dependence of the self-diffusivity can be expressed using the Vogel-Fulcher-Tammann equation, and estimates of the fragility index of the system indicates a fragile glass former. At lower temperatures, signatures of additional relaxation processes are observed in the various dynamical quantities with a three-step relaxation observed in the Fs(k,t).
GMRES acceleration of computational fluid dynamics codes
NASA Technical Reports Server (NTRS)
Wigton, L. B.; Yu, N. J.; Young, D. P.
1985-01-01
The generalized minimal residual algorithm (GMRES) is a conjugate-gradient like method that applies directly to nonsymmetric linear systems of equations. In this paper, GMRES is modified to handle nonlinear equations characteristic of computational fluid dynamics. Attention is devoted to the concept of preconditioning and the role it plays in assuring rapid convergence. A formulation is developed that allows GMRES to be preconditioned by the solution procedures already built into existing computer codes. Examples are provided that demonstrate the ability of GMRES to greatly improve the robustness and rate of convergence of current state-of-the-art fluid dynamics codes. Theoretical aspects of GMRES are presented that explain why it works. Finally, the advantage GMRES enjoys over related methods such as conjugate gradients are discussed.
Fluid dynamics of cytotoxic safety cabinets.
Braconnier, R; Bonthoux, F
2010-03-01
This study investigated the specific fluid dynamics characteristics of cytotoxic safety cabinets (CSC), particularly those used in cancer drug reconstitution operations. Measurements taken on site were used to derive characteristic data for these cabinets. An in-depth laboratory investigation of airflows inside another CSC was also conducted. Anemometric values recorded on these two installations enabled the experimental validation of computational fluid dynamics methods applied to CSC. The digital flow simulations conducted provide a better understanding of the detailed flow structure inside a CSC and made it possible to study the influence of different operating parameters on the air velocity distribution inside the cabinet front opening: recycled air temperature, product protection airflow rate, suction openings spatial distribution, air compensation mode and draughts, operator arm penetration, and operator presence in front of the cabinet. PMID:20007340
Computational fluid dynamics - The coming revolution
NASA Technical Reports Server (NTRS)
Graves, R. A., Jr.
1982-01-01
The development of aerodynamic theory is traced from the days of Aristotle to the present, with the next stage in computational fluid dynamics dependent on superspeed computers for flow calculations. Additional attention is given to the history of numerical methods inherent in writing computer codes applicable to viscous and inviscid analyses for complex configurations. The advent of the superconducting Josephson junction is noted to place configurational demands on computer design to avoid limitations imposed by the speed of light, and a Japanese projection of a computer capable of several hundred billion operations/sec is mentioned. The NASA Numerical Aerodynamic Simulator is described, showing capabilities of a billion operations/sec with a memory of 240 million words using existing technology. Near-term advances in fluid dynamics are discussed.
Drop formation, pinch-off dynamics and liquid transfer of simple and complex fluids
NASA Astrophysics Data System (ADS)
Dinic, Jelena; Sharma, Vivek
Liquid transfer and drop formation processes underlying jetting, spraying, coating, and printing - inkjet, screen, roller-coating, gravure, nanoimprint hot embossing, 3D - often involve formation of unstable columnar necks. Capillary-driven thinning of such necks and their pinchoff dynamics are determined by a complex interplay of inertial, viscous and capillary stresses for simple, Newtonian fluids. Micro-structural changes in response to extensional flow field that arises within the thinning neck give rise to additional viscoelastic stresses in complex, non- Newtonian fluids. Using FLOW-3D, we simulate flows realized in prototypical geometries (dripping and liquid bridge stretched between two parallel plates) used for studying pinch-off dynamics and influence of microstructure and viscoelasticity. In contrast with often-used 1D or 2D models, FLOW-3D allows a robust evaluation of the magnitude of the underlying stresses and extensional flow field (both uniformity and magnitude). We find that the simulated radius evolution profiles match the pinch-off dynamics that are experimentally-observed and theoretically-predicted for model Newtonian fluids and complex fluids.
Isentropic fluid dynamics in a curved pipe
NASA Astrophysics Data System (ADS)
Colombo, Rinaldo M.; Holden, Helge
2016-10-01
In this paper we study isentropic flow in a curved pipe. We focus on the consequences of the geometry of the pipe on the dynamics of the flow. More precisely, we present the solution of the general Cauchy problem for isentropic fluid flow in an arbitrarily curved, piecewise smooth pipe. We consider initial data in the subsonic regime, with small total variation about a stationary solution. The proof relies on the front-tracking method and is based on [1].
Geometric methods in computational fluid dynamics. [turbomachinery
NASA Technical Reports Server (NTRS)
Eiseman, P. R.
1980-01-01
General methods for the construction of geometric computational fluid dynamic algorithms are presented which simulate a variety of flow fields in various nontrivial regions. Included are: basic developments with tensors; various forms for the equations of motion; generalized numerical methods and boundary conditions; and methods for mesh generation to meet the strong geometric constraints of turbomachines. Coordinate generation is shown generally to yield mesh descriptions from one or more transformations that are smoothly joined together to form a composite mesh.
Delaunay triangulation and computational fluid dynamics meshes
NASA Technical Reports Server (NTRS)
Posenau, Mary-Anne K.; Mount, David M.
1992-01-01
In aerospace computational fluid dynamics (CFD) calculations, the Delaunay triangulation of suitable quadrilateral meshes can lead to unsuitable triangulated meshes. Here, we present case studies which illustrate the limitations of using structured grid generation methods which produce points in a curvilinear coordinate system for subsequent triangulations for CFD applications. We discuss conditions under which meshes of quadrilateral elements may not produce a Delaunay triangulation suitable for CFD calculations, particularly with regard to high aspect ratio, skewed quadrilateral elements.
Thin film dynamics of viscoelastic fluids
NASA Astrophysics Data System (ADS)
Lebon, Luc; Limat, Laurent
2012-11-01
We present here viscoelastic fluids in thin film flows, such as liquid bells or liquid curtains. The viscoelastic property of the liquids exhibits specific dynamics in such flows. In the case of bells, the elastic strength tends to extend the bell size for example. In the case of curtain flows, original behaviour of holes are observed with specific growth mechanism for bubbles trapped in the flow.
Anderson, Roger N.; Boulanger, Albert; Bagdonas, Edward P.; Xu, Liqing; He, Wei
1996-01-01
The invention utilizes 3-D and 4-D seismic surveys as a means of deriving information useful in petroleum exploration and reservoir management. The methods use both single seismic surveys (3-D) and multiple seismic surveys separated in time (4-D) of a region of interest to determine large scale migration pathways within sedimentary basins, and fine scale drainage structure and oil-water-gas regions within individual petroleum producing reservoirs. Such structure is identified using pattern recognition tools which define the regions of interest. The 4-D seismic data sets may be used for data completion for large scale structure where time intervals between surveys do not allow for dynamic evolution. The 4-D seismic data sets also may be used to find variations over time of small scale structure within individual reservoirs which may be used to identify petroleum drainage pathways, oil-water-gas regions and, hence, attractive drilling targets. After spatial orientation, and amplitude and frequency matching of the multiple seismic data sets, High Amplitude Event (HAE) regions consistent with the presence of petroleum are identified using seismic attribute analysis. High Amplitude Regions are grown and interconnected to establish plumbing networks on the large scale and reservoir structure on the small scale. Small scale variations over time between seismic surveys within individual reservoirs are identified and used to identify drainage patterns and bypassed petroleum to be recovered. The location of such drainage patterns and bypassed petroleum may be used to site wells.
Anderson, R.N.; Boulanger, A.; Bagdonas, E.P.; Xu, L.; He, W.
1996-12-17
The invention utilizes 3-D and 4-D seismic surveys as a means of deriving information useful in petroleum exploration and reservoir management. The methods use both single seismic surveys (3-D) and multiple seismic surveys separated in time (4-D) of a region of interest to determine large scale migration pathways within sedimentary basins, and fine scale drainage structure and oil-water-gas regions within individual petroleum producing reservoirs. Such structure is identified using pattern recognition tools which define the regions of interest. The 4-D seismic data sets may be used for data completion for large scale structure where time intervals between surveys do not allow for dynamic evolution. The 4-D seismic data sets also may be used to find variations over time of small scale structure within individual reservoirs which may be used to identify petroleum drainage pathways, oil-water-gas regions and, hence, attractive drilling targets. After spatial orientation, and amplitude and frequency matching of the multiple seismic data sets, High Amplitude Event (HAE) regions consistent with the presence of petroleum are identified using seismic attribute analysis. High Amplitude Regions are grown and interconnected to establish plumbing networks on the large scale and reservoir structure on the small scale. Small scale variations over time between seismic surveys within individual reservoirs are identified and used to identify drainage patterns and bypassed petroleum to be recovered. The location of such drainage patterns and bypassed petroleum may be used to site wells. 22 figs.
Efficient Numerical Modeling of 3D, Half-Space, Slow-Slip and Quasi-Dynamic Earthquake Ruptures
NASA Astrophysics Data System (ADS)
Bradley, A. M.; Segall, P.
2011-12-01
Motivated by the hypothesis that dilatancy plays a critical role in faulting in subduction zones, we are developing FDRA2 (Fault Dynamics with the Radiation-damping Approximation), a software package to simulate three-dimensional quasi-dynamic faulting that includes rate-state friction, thermal pressurization, and dilatancy (following Segall and Rice [1995]) in a finite-width shear zone. This work builds on the two-dimensional simulations performed by FDRA1 (Bradley and Segall [AGU 2010], Segall and Bradley [submitted]). These simulations show that at lower background effective normal stress (\\bar σ), slow slip events occur spontaneously, whereas at higher \\bar σ , slip is inertially limited. At intermediate \\bar σ , dynamic events are followed by quiescent periods and then long durations of repeating slow slip events. Models with depth-dependent properties produce sequences similar to those observed in Cascadia. Like FDRA1, FDRA2 solves partial differential equations in pressure and temperature on profiles normal to the fault. The diffusion equations are discretized in space using finite differences on a nonuniform mesh having greater density near the fault. The full system of equations is a semiexplicit index-1 differential algebraic equation (DAE) in slip, slip rate, state, fault zone porosity, pressure, and temperature. We integrate state, porosity, and slip explicitly; solve the momentum balance equation on the fault for slip rate; and integrate pressure and temperature implicitly. Adaptive time steps are limited by accuracy and the stability criterion governing explicit integration of hyperbolic, but not the more stringent one governing parabolic, PDE. To compute elasticity in a 3D half-space, FDRA2 compresses the large, dense matrix arising from the boundary element method using an H-matrix. The work to perform a matrix-vector product scales almost linearly, rather than quadratically, in the number of fault cells. A new technique to relate the error
NASA Astrophysics Data System (ADS)
Yoshida, M.; Tajima, F.
2012-04-01
Water content in the mantle transition zone (MTZ) has been broadly debated in the Earth science community as a key issue for plate dynamics [e.g., Bercovici and Karato, 2003]. In this study, a systematic series of three-dimensional (3D) numerical simulation are performed in an attempt to verify two hypotheses for plate subduction with effects of deep water transport: (1) the small-scale behavior of subducted oceanic plate in the MTZ; and (2) the role of subducted crust in the MTZ. These hypotheses are postulated based on the seismic observations characterized by large-scale flattened high velocity anomalies (i.e., stagnant slabs) in the MTZ and discontinuity depth variations. The proposed model states that under wet conditions the subducted plate main body of peridotite (olivine rich) is abutted by subducted crustal materials (majorite rich) at the base of the MTZ. The computational domain of mantle convection is confined to 3D regional spherical-shell geometry with a thickness of 1000 km and a lateral extent of 10° × 30° in the latitudinal and longitudinal directions. A semi-dynamic model of subduction zone [Morishige et al., 2010] is applied to let the highly viscous, cold oceanic plate subduct. Weak (low-viscosity) fault zones (WFZs), which presumably correspond to the fault boundaries of large subduction earthquakes, are imposed on the top part of subducting plates. The phase transitions of olivine to wadsleyite and ringwoodite to perovskite+magnesiowüstite with Clapeyron slopes under both "dry" and "wet" conditions are considered based on recent high pressure experiments [e.g., Ohtani and Litasov, 2006]. Another recent experiment provides new evidence for lower-viscosity (weaker strength) of garnet-rich zones than the olivine dominant mantle under wet conditions [Katayama and Karato, 2008]. According to this, the effect of viscosity reduction of oceanic crust is considered under wet condition in the MTZ. Results show that there is a substantial difference
The fluid dynamics of the chocolate fountain
NASA Astrophysics Data System (ADS)
Townsend, Adam K.; Wilson, Helen J.
2016-01-01
We consider the fluid dynamics of the chocolate fountain. Molten chocolate is a mildly shear-thinning non-Newtonian fluid. Dividing the flow into three main domains—the pumped flow up the centre, the film flow over each dome, and the freely falling curtain flow between the domes—we generate a wide-ranging study of Newtonian and non-Newtonian fluid mechanics. The central pumped flow is a benchmark to elucidate the effects of shear-thinning. The dome flow can be modelled as a thin-film flow with the leading-order effects being a simple balance of gravity and viscosity. Finally, the curtain flow is analytically intractable but is related to the existing theory of water bells (both inviscid and viscous). In pipe flow, Newtonian fluids exhibit a parabolic velocity profile; shear-thinning makes the profile more blunted. In thin-film flow over the dome, gravitational and viscous effects balance and the dome shape is not important beyond the local slope. We find that the chocolate thins and slows down as it travels down the dome. Finally, in the curtain flow, we predict the shape of the falling sheet for an inviscid fluid, and compare this with the literature to predict the shape for a viscous fluid, having shown that viscous forces are too great to ignore. We also find that the primary effect driving the shape of the curtain (which falls inwards towards the axis of the fountain) is surface tension. We find that the three domains provide excellent introductions to non-Newtonian mechanics, the important mathematical technique of scaling, and how to manipulate existing data to make our own predictions. We also find that the topic generates interest among the public in our engagement work.
Lockwood, Sarah Y; Meisel, Jayda E; Monsma, Frederick J; Spence, Dana M
2016-02-01
The process of bringing a drug to market involves many steps, including the preclinical stage, where various properties of the drug candidate molecule are determined. These properties, which include drug absorption, distribution, metabolism, and excretion, are often displayed in a pharmacokinetic (PK) profile. While PK profiles are determined in animal models, in vitro systems that model in vivo processes are available, although each possesses shortcomings. Here, we present a 3D-printed, diffusion-based, and dynamic in vitro PK device. The device contains six flow channels, each with integrated porous membrane-based insert wells. The pores of these membranes enable drugs to freely diffuse back and forth between the flow channels and the inserts, thus enabling both loading and clearance portions of a standard PK curve to be generated. The device is designed to work with 96-well plate technology and consumes single-digit milliliter volumes to generate multiple PK profiles, simultaneously. Generation of PK profiles by use of the device was initially performed with fluorescein as a test molecule. Effects of such parameters as flow rate, loading time, volume in the insert well, and initial concentration of the test molecule were investigated. A prediction model was generated from this data, enabling the user to predict the concentration of the test molecule at any point along the PK profile within a coefficient of variation of ∼ 5%. Depletion of the analyte from the well was characterized and was determined to follow first-order rate kinetics, indicated by statistically equivalent (p > 0.05) depletion half-lives that were independent of the starting concentration. A PK curve for an approved antibiotic, levofloxacin, was generated to show utility beyond the fluorescein test molecule.
NASA Technical Reports Server (NTRS)
Tezduyar, Tayfun E.
1998-01-01
This is a final report as far as our work at University of Minnesota is concerned. The report describes our research progress and accomplishments in development of high performance computing methods and tools for 3D finite element computation of aerodynamic characteristics and fluid-structure interactions (FSI) arising in airdrop systems, namely ram-air parachutes and round parachutes. This class of simulations involves complex geometries, flexible structural components, deforming fluid domains, and unsteady flow patterns. The key components of our simulation toolkit are a stabilized finite element flow solver, a nonlinear structural dynamics solver, an automatic mesh moving scheme, and an interface between the fluid and structural solvers; all of these have been developed within a parallel message-passing paradigm.
Dynamics of fluid mixing in separated flows
NASA Astrophysics Data System (ADS)
Leder, A.
1991-05-01
Separated flows at high Re (>103) are highly turbulent. In some situations the turbulence generation and mixing processes associated with flow separation are desirable, e.g., in heat exchangers or in many chemical engineering applications. In others, e.g., stalled airfoils, separation must be avoided as it causes loss in pressure and kinetic energy. To control the phenomenon effectively, physical mechanisms of flow separation and related aspects, such as the growth of flow instabilities in shear layers, the process of vortex formation, and the dynamics of fluid mixing in recirculating flow regions, must be understood. In many cases numerical procedures, e.g., Navier-Stokes calculations including k-ɛ turbulence modeling, fail to predict real physical mechanisms in separated flows.1,2 Separated flows in the lee of bluff bodies have been studied for many years.3,4 However, accurate measurements of the magnitude and direction of velocities and the magnitude of the terms of the Reynolds stress tensor have been restricted by the unsuitability of the hot-wire anemometer in recirculating flows. The development of the pulsed-wire anemometer, flying hot-wire anemometer, and laser-Doppler anemometry (LDA) allows more reliable measurements also in turbulent separated flows.5-8 The aim of this paper is to investigate the dynamics of undisturbed fluid mixing in separated regions of 2-D, incompressible flows with visualization techniques and LDA. Measurements were performed with a vertical flat plate model, mounted in a closed-circuit wind tunnel at low blockage ratio. Because of the noninvasive character, optical techniques like LDA are more suitable to analyze complex fluid motions than pulsed-wire and flying-wire anemometry. The LDA system used to investigate turbulent flow structures consists of a two-channel version operating in backscatter mode and a specifically developed phase detector to extract phase-averaged information from recorded measurement ensembles.9 Endplates
NASA Astrophysics Data System (ADS)
Tanaka, Eiichi; Kudo, Hiroyuki
2010-05-01
We have reported a block-iterative algorithm named DRAMA for image reconstruction for emission tomography (Tanaka and Kudo 2003 Phys. Med. Biol. 48 1405-22). DRAMA is a modified version of the row-action maximum likelihood algorithm (RAMLA), in which the relaxation parameter is subset dependent and is changed in such a way that the noise propagation from subsets to the reconstructed image is substantially independent of the access order of the subsets. The algorithm provides fast convergence with a reasonable signal-to-noise ratio. The optimal relaxation parameter has been derived assuming a two-dimensional (2D)-PET model, and detailed performance in three-dimensional (3D) reconstruction has not been clear enough. We have developed the new version 'DRAMA-3D', based on the 3D-PET model. The optimal relaxation parameter is a function of the access order of the subsets and the ring difference, and its value is determined by simple formulas from the design parameters of the PET scanner, the operating conditions and the post-smoothing resolution. In this paper, we present the theory of DRAMA-3D, the results of simulation studies on the performance of DRAMA-3D and the comparative studies of the related algorithms. It is shown that DRAMA-3D is robust for various access orders of subsets and is suitable to realize one-pass (single-iteration) reconstruction.
Computational Fluid Dynamics - Applications in Manufacturing Processes
NASA Astrophysics Data System (ADS)
Beninati, Maria Laura; Kathol, Austin; Ziemian, Constance
2012-11-01
A new Computational Fluid Dynamics (CFD) exercise has been developed for the undergraduate introductory fluid mechanics course at Bucknell University. The goal is to develop a computational exercise that students complete which links the manufacturing processes course and the concurrent fluid mechanics course in a way that reinforces the concepts in both. In general, CFD is used as a tool to increase student understanding of the fundamentals in a virtual world. A ``learning factory,'' which is currently in development at Bucknell seeks to use the laboratory as a means to link courses that previously seemed to have little correlation at first glance. A large part of the manufacturing processes course is a project using an injection molding machine. The flow of pressurized molten polyurethane into the mold cavity can also be an example of fluid motion (a jet of liquid hitting a plate) that is applied in manufacturing. The students will run a CFD process that captures this flow using their virtual mold created with a graphics package, such as SolidWorks. The laboratory structure is currently being implemented and analyzed as a part of the ``learning factory''. Lastly, a survey taken before and after the CFD exercise demonstrate a better understanding of both the CFD and manufacturing process.
Computer animation challenges for computational fluid dynamics
NASA Astrophysics Data System (ADS)
Vines, Mauricio; Lee, Won-Sook; Mavriplis, Catherine
2012-07-01
Computer animation requirements differ from those of traditional computational fluid dynamics (CFD) investigations in that visual plausibility and rapid frame update rates trump physical accuracy. We present an overview of the main techniques for fluid simulation in computer animation, starting with Eulerian grid approaches, the Lattice Boltzmann method, Fourier transform techniques and Lagrangian particle introduction. Adaptive grid methods, precomputation of results for model reduction, parallelisation and computation on graphical processing units (GPUs) are reviewed in the context of accelerating simulation computations for animation. A survey of current specific approaches for the application of these techniques to the simulation of smoke, fire, water, bubbles, mixing, phase change and solid-fluid coupling is also included. Adding plausibility to results through particle introduction, turbulence detail and concentration on regions of interest by level set techniques has elevated the degree of accuracy and realism of recent animations. Basic approaches are described here. Techniques to control the simulation to produce a desired visual effect are also discussed. Finally, some references to rendering techniques and haptic applications are mentioned to provide the reader with a complete picture of the challenges of simulating fluids in computer animation.
Structure and dynamics of electrorheological fluids
Martin, J.E.; Odinek, J.; Halsey, T.C.; Kamien, R.
1998-01-01
We have used two-dimensional light scattering to study the structure and dynamics of a single-scattering electrorheological fluid in the quiescent state and in steady and oscillatory shear. Studies of the quiescent fluid show that particle columns grow in two stages. Particles first chain along the electric field, causing scattering lobes to appear orthogonal to the field, and then aggregate into columns, causing the scattering lobes to move to smaller angles. Column formation can be understood in terms of a thermal coarsening model we present, whereas the early-time scattering in the direction parallel to the field can be compared to the theory of line liquids. In simple shear the scattering lobes are inclined in the direction of fluid vorticity, in detailed agreement with the independent droplet model of the shear thinning viscosity. In oscillatory shear the orientation of the scattering lobes varies nonsinusoidally. This nonlinear dynamics is described by a kinetic chain model, which provides a theory of the nonlinear shear rheology in arbitrary shear flows. {copyright} {ital 1998} {ital The American Physical Society}
NASA Computational Fluid Dynamics Conference. Volume 1: Sessions 1-6
NASA Technical Reports Server (NTRS)
1989-01-01
Presentations given at the NASA Computational Fluid Dynamics (CFD) Conference held at the NASA Ames Research Center, Moffett Field, California, March 7-9, 1989 are given. Topics covered include research facility overviews of CFD research and applications, validation programs, direct simulation of compressible turbulence, turbulence modeling, advances in Runge-Kutta schemes for solving 3-D Navier-Stokes equations, grid generation and invicid flow computation around aircraft geometries, numerical simulation of rotorcraft, and viscous drag prediction for rotor blades.
Yuan, Jianmin; Teng, Zhongzhao; Feng, Jiaxuan; Zhang, Yongxue; Brown, Adam J; Gillard, Jonathan H; Jing, Zaiping; Lu, Qingsheng
2015-08-01
Mechanical analysis has been shown to be complementary to luminal stenosis in assessing atherosclerotic plaque vulnerability. However, patient-specific material properties are not available and the effect of material properties variability has not been fully quantified. Media and fibrous cap (FC) strips from carotid endarterectomy samples were classified into hard, intermediate and soft according to their incremental Young's modulus. Lipid and intraplaque haemorrhage/thrombus strips were classified as hard and soft. Idealised geometry-based 3D fluid-structure interaction analyses were performed to assess the impact of material property variability in predicting maximum principal stress (Stress-P1 ) and stretch (Stretch-P1 ). When FC was thick (1000 or 600 µm), Stress-P1 at the shoulder was insensitive to changes in material stiffness, whereas Stress-P1 at mid FC changed significantly. When FC was thin (200 or 65 µm), high stress concentrations shifted from the shoulder region to mid FC, and Stress-P1 became increasingly sensitive to changes in material properties, in particular at mid FC. Regardless of FC thickness, Stretch-P1 at these locations was sensitive to changes in material properties. Variability in tissue material properties influences both the location and overall stress/stretch value. This variability needs to be accounted for when interpreting the results of mechanical modelling. PMID:25940741
Yuan, Jianmin; Teng, Zhongzhao; Feng, Jiaxuan; Zhang, Yongxue; Brown, Adam J; Gillard, Jonathan H; Jing, Zaiping; Lu, Qingsheng
2015-08-01
Mechanical analysis has been shown to be complementary to luminal stenosis in assessing atherosclerotic plaque vulnerability. However, patient-specific material properties are not available and the effect of material properties variability has not been fully quantified. Media and fibrous cap (FC) strips from carotid endarterectomy samples were classified into hard, intermediate and soft according to their incremental Young's modulus. Lipid and intraplaque haemorrhage/thrombus strips were classified as hard and soft. Idealised geometry-based 3D fluid-structure interaction analyses were performed to assess the impact of material property variability in predicting maximum principal stress (Stress-P1 ) and stretch (Stretch-P1 ). When FC was thick (1000 or 600 µm), Stress-P1 at the shoulder was insensitive to changes in material stiffness, whereas Stress-P1 at mid FC changed significantly. When FC was thin (200 or 65 µm), high stress concentrations shifted from the shoulder region to mid FC, and Stress-P1 became increasingly sensitive to changes in material properties, in particular at mid FC. Regardless of FC thickness, Stretch-P1 at these locations was sensitive to changes in material properties. Variability in tissue material properties influences both the location and overall stress/stretch value. This variability needs to be accounted for when interpreting the results of mechanical modelling.
Fluid dynamics of the cerebral aqueduct.
Jacobson, E E; Fletcher, D F; Morgan, M K; Johnston, I H
1996-01-01
Despite a multitude of theories describing the mechanics of the intracranial spaces in diseases such as hydrocephalus, little is known about the mechanics of normal CSF flow. A pressure difference is required to drive CSF flow. Knowing that the pressure difference driving fluid through the aqueduct is beyond the resolution of clinically used pressure transducers, a computational fluid dynamics program was used to analyze flow through an aqueduct shape. Flow through this duct was compared with that through a cylinder and through a double hourglass. Both steady and oscillating flows were tested, revealing that only 1.1 Pa of pressure is required to move CSF through the aqueduct. This suggests that normally less than 5% of the total resistance to CSF flow within the CSF pathways occurs in the aqueduct.
Fluid dynamical description of relativistic nuclear collisions
NASA Technical Reports Server (NTRS)
Nix, J. R.; Strottman, D.
1982-01-01
On the basis of both a conventional relativistic nuclear fluid dynamic model and a two fluid generalization that takes into account the interpenetration of the target and projectile upon contact, collisions between heavy nuclei moving at relativistic speeds are calculated. This is done by solving the relevant equations of motion numerically in three spatial dimensions by use of particle in cell finite difference computing techniques. The effect of incorporating a density isomer, or quasistable state, in the nuclear equation of state at three times normal nuclear density, and the effect of doubling the nuclear compressibility coefficient are studied. For the reaction 20Ne + 238U at a laboratory bombarding energy per nucleon of 393 MeV, the calculated distributions in energy and angle of outgoing charged particles are compared with recent experimental data both integrated over all impact parameters and for nearly central collisions.
NASA Astrophysics Data System (ADS)
Dunkerley, David A. P.; Funk, Tobias; Speidel, Michael A.
2016-03-01
Scanning-beam digital x-ray (SBDX) is an inverse geometry x-ray fluoroscopy system capable of tomosynthesis-based 3D catheter tracking. This work proposes a method of dose-reduced 3D tracking using dynamic electronic collimation (DEC) of the SBDX scanning x-ray tube. Positions in the 2D focal spot array are selectively activated to create a regionof- interest (ROI) x-ray field around the tracked catheter. The ROI position is updated for each frame based on a motion vector calculated from the two most recent 3D tracking results. The technique was evaluated with SBDX data acquired as a catheter tip inside a chest phantom was pulled along a 3D trajectory. DEC scans were retrospectively generated from the detector images stored for each focal spot position. DEC imaging of a catheter tip in a volume measuring 11.4 cm across at isocenter required 340 active focal spots per frame, versus 4473 spots in full-FOV mode. The dose-area-product (DAP) and peak skin dose (PSD) for DEC versus full field-of-view (FOV) scanning were calculated using an SBDX Monte Carlo simulation code. DAP was reduced to 7.4% to 8.4% of the full-FOV value, consistent with the relative number of active focal spots (7.6%). For image sequences with a moving catheter, PSD was 33.6% to 34.8% of the full-FOV value. The root-mean-squared-deviation between DEC-based 3D tracking coordinates and full-FOV 3D tracking coordinates was less than 0.1 mm. The 3D distance between the tracked tip and the sheath centerline averaged 0.75 mm. Dynamic electronic collimation can reduce dose with minimal change in tracking performance.
Geophysical fluid dynamics: whence, whither and why?
NASA Astrophysics Data System (ADS)
Vallis, Geoffrey K.
2016-08-01
This article discusses the role of geophysical fluid dynamics (GFD) in understanding the natural environment, and in particular the dynamics of atmospheres and oceans on Earth and elsewhere. GFD, as usually understood, is a branch of the geosciences that deals with fluid dynamics and that, by tradition, seeks to extract the bare essence of a phenomenon, omitting detail where possible. The geosciences in general deal with complex interacting systems and in some ways resemble condensed matter physics or aspects of biology, where we seek explanations of phenomena at a higher level than simply directly calculating the interactions of all the constituent parts. That is, we try to develop theories or make simple models of the behaviour of the system as a whole. However, these days in many geophysical systems of interest, we can also obtain information for how the system behaves by almost direct numerical simulation from the governing equations. The numerical model itself then explicitly predicts the emergent phenomena-the Gulf Stream, for example-something that is still usually impossible in biology or condensed matter physics. Such simulations, as manifested, for example, in complicated general circulation models, have in some ways been extremely successful and one may reasonably now ask whether understanding a complex geophysical system is necessary for predicting it. In what follows we discuss such issues and the roles that GFD has played in the past and will play in the future.
Geophysical fluid dynamics: whence, whither and why?
2016-01-01
This article discusses the role of geophysical fluid dynamics (GFD) in understanding the natural environment, and in particular the dynamics of atmospheres and oceans on Earth and elsewhere. GFD, as usually understood, is a branch of the geosciences that deals with fluid dynamics and that, by tradition, seeks to extract the bare essence of a phenomenon, omitting detail where possible. The geosciences in general deal with complex interacting systems and in some ways resemble condensed matter physics or aspects of biology, where we seek explanations of phenomena at a higher level than simply directly calculating the interactions of all the constituent parts. That is, we try to develop theories or make simple models of the behaviour of the system as a whole. However, these days in many geophysical systems of interest, we can also obtain information for how the system behaves by almost direct numerical simulation from the governing equations. The numerical model itself then explicitly predicts the emergent phenomena—the Gulf Stream, for example—something that is still usually impossible in biology or condensed matter physics. Such simulations, as manifested, for example, in complicated general circulation models, have in some ways been extremely successful and one may reasonably now ask whether understanding a complex geophysical system is necessary for predicting it. In what follows we discuss such issues and the roles that GFD has played in the past and will play in the future.
Geophysical fluid dynamics: whence, whither and why?
2016-01-01
This article discusses the role of geophysical fluid dynamics (GFD) in understanding the natural environment, and in particular the dynamics of atmospheres and oceans on Earth and elsewhere. GFD, as usually understood, is a branch of the geosciences that deals with fluid dynamics and that, by tradition, seeks to extract the bare essence of a phenomenon, omitting detail where possible. The geosciences in general deal with complex interacting systems and in some ways resemble condensed matter physics or aspects of biology, where we seek explanations of phenomena at a higher level than simply directly calculating the interactions of all the constituent parts. That is, we try to develop theories or make simple models of the behaviour of the system as a whole. However, these days in many geophysical systems of interest, we can also obtain information for how the system behaves by almost direct numerical simulation from the governing equations. The numerical model itself then explicitly predicts the emergent phenomena—the Gulf Stream, for example—something that is still usually impossible in biology or condensed matter physics. Such simulations, as manifested, for example, in complicated general circulation models, have in some ways been extremely successful and one may reasonably now ask whether understanding a complex geophysical system is necessary for predicting it. In what follows we discuss such issues and the roles that GFD has played in the past and will play in the future. PMID:27616918
Fluid flow dynamics under location uncertainty
NASA Astrophysics Data System (ADS)
Mémin, Etienne
2014-03-01
We present a derivation of a stochastic model of Navier Stokes equations that relies on a decomposition of the velocity fields into a differentiable drift component and a time uncorrelated uncertainty random term. This type of decomposition is reminiscent in spirit to the classical Reynolds decomposition. However, the random velocity fluctuations considered here are not differentiable with respect to time, and they must be handled through stochastic calculus. The dynamics associated with the differentiable drift component is derived from a stochastic version of the Reynolds transport theorem. It includes in its general form an uncertainty dependent "subgrid" bulk formula that cannot be immediately related to the usual Boussinesq eddy viscosity assumption constructed from thermal molecular agitation analogy. This formulation, emerging from uncertainties on the fluid parcels location, explains with another viewpoint some subgrid eddy diffusion models currently used in computational fluid dynamics or in geophysical sciences and paves the way for new large-scales flow modelling. We finally describe an applications of our formalism to the derivation of stochastic versions of the Shallow water equations or to the definition of reduced order dynamical systems.
NASA Astrophysics Data System (ADS)
Tasianas, A.; Bunz, S.
2013-12-01
The Snøhvit hydrocarbon reservoir in the SW Barents Sea is one of two storage sites of CO2 on the Norwegian Margin. Within the context of the ECO2 project we acquired bathymetric and P-Cable high resolution 3D seismic data to characterize fluid flow phenomena on the seabed and in the shallow subsurface and better understand the pathways and mechanisms related to fluid flow. Two P-Cable high resolution cubes were obtained in summer 2011 and one of them was partially repeated in summer 2013. The objective of the time-lapse survey in 2013 was mainly to develop the P-Cable technology into an effective monitoring technology at CCS sites. In the first survey from 2011, we observe two different kinds of pockmarks. Several hundreds of small circular pockmarks, the 'unit' pockmarks (UPs), occur scattered over an area of about 14 km2. They are up to 20 m in diameter and approximately 1 m deep. In addition, seven larger, semi-circular to elliptic pockmarks, the 'normal' pockmarks, (NPs) align along a NW/SE direction. Pockmarks are often found within glacial plough marks and have affected their internal structure. A clinoform system in the subsurface shows multiple high-amplitude anomalies indicating the presence of gas in shallow sediments. Eastern edges of clinoforms are usually N/S or NW/SE oriented and their orientation often coincides with the direction of alignment of NP 2-6. Clinoforms may thus act as fluid flow pathways and determine the location of NPs at the seabed. UPs can be associated in strings developing to the sides of NPs. The strings seem to follow the same orientation as fractures or underlying vertical weakness zones. Pockmark genesis can be related to various factors but the abundance of plough marks at the seabed suggests a mechanism related to iceberg scouring at the seafloor during ice retreat. Pockmark formation is thus not a contemporary phenomenon but a paleo-event probably linked to a deglaciation.
Direct modeling for computational fluid dynamics
NASA Astrophysics Data System (ADS)
Xu, Kun
2015-06-01
All fluid dynamic equations are valid under their modeling scales, such as the particle mean free path and mean collision time scale of the Boltzmann equation and the hydrodynamic scale of the Navier-Stokes (NS) equations. The current computational fluid dynamics (CFD) focuses on the numerical solution of partial differential equations (PDEs), and its aim is to get the accurate solution of these governing equations. Under such a CFD practice, it is hard to develop a unified scheme that covers flow physics from kinetic to hydrodynamic scales continuously because there is no such governing equation which could make a smooth transition from the Boltzmann to the NS modeling. The study of fluid dynamics needs to go beyond the traditional numerical partial differential equations. The emerging engineering applications, such as air-vehicle design for near-space flight and flow and heat transfer in micro-devices, do require further expansion of the concept of gas dynamics to a larger domain of physical reality, rather than the traditional distinguishable governing equations. At the current stage, the non-equilibrium flow physics has not yet been well explored or clearly understood due to the lack of appropriate tools. Unfortunately, under the current numerical PDE approach, it is hard to develop such a meaningful tool due to the absence of valid PDEs. In order to construct multiscale and multiphysics simulation methods similar to the modeling process of constructing the Boltzmann or the NS governing equations, the development of a numerical algorithm should be based on the first principle of physical modeling. In this paper, instead of following the traditional numerical PDE path, we introduce direct modeling as a principle for CFD algorithm development. Since all computations are conducted in a discretized space with limited cell resolution, the flow physics to be modeled has to be done in the mesh size and time step scales. Here, the CFD is more or less a direct
S3D: An interactive surface grid generation tool
NASA Technical Reports Server (NTRS)
Luh, Raymond Ching-Chung; Pierce, Lawrence E.; Yip, David
1992-01-01
S3D, an interactive software tool for surface grid generation, is described. S3D provides the means with which a geometry definition based either on a discretized curve set or a rectangular set can be quickly processed towards the generation of a surface grid for computational fluid dynamics (CFD) applications. This is made possible as a result of implementing commonly encountered surface gridding tasks in an environment with a highly efficient and user friendly graphical interface. Some of the more advanced features of S3D include surface-surface intersections, optimized surface domain decomposition and recomposition, and automated propagation of edge distributions to surrounding grids.
Domain decomposition algorithms and computational fluid dynamics
NASA Technical Reports Server (NTRS)
Chan, Tony F.
1988-01-01
Some of the new domain decomposition algorithms are applied to two model problems in computational fluid dynamics: the two-dimensional convection-diffusion problem and the incompressible driven cavity flow problem. First, a brief introduction to the various approaches of domain decomposition is given, and a survey of domain decomposition preconditioners for the operator on the interface separating the subdomains is then presented. For the convection-diffusion problem, the effect of the convection term and its discretization on the performance of some of the preconditioners is discussed. For the driven cavity problem, the effectiveness of a class of boundary probe preconditioners is examined.
Kinematics and Fluid Dynamics of Jellyfish Maneuvering
NASA Astrophysics Data System (ADS)
Miller, Laura; Hoover, Alex
2014-11-01
Jellyfish propel themselves through the water through periodic contractions of their elastic bells. Some jellyfish, such as the moon jellyfish Aurelia aurita and the upside down jellyfish Cassiopea xamachana, can perform turns via asymmetric contractions of the bell. The fluid dynamics of jellyfish forward propulsion and turning is explored here by analyzing the contraction kinematics of several species and using flow visualization to quantify the resulting flow fields. The asymmetric contraction and structure of the jellyfish generates asymmetries in the starting and stopping vortices. This creates a diagonal jet and a net torque acting on the jellyfish. Results are compared to immersed boundary simulations
Three-Dimensional Computational Fluid Dynamics
Haworth, D.C.; O'Rourke, P.J.; Ranganathan, R.
1998-09-01
Computational fluid dynamics (CFD) is one discipline falling under the broad heading of computer-aided engineering (CAE). CAE, together with computer-aided design (CAD) and computer-aided manufacturing (CAM), comprise a mathematical-based approach to engineering product and process design, analysis and fabrication. In this overview of CFD for the design engineer, our purposes are three-fold: (1) to define the scope of CFD and motivate its utility for engineering, (2) to provide a basic technical foundation for CFD, and (3) to convey how CFD is incorporated into engineering product and process design.
Supercomputer applications in computational fluid dynamics
NASA Technical Reports Server (NTRS)
Holst, Terry L.
1989-01-01
The field of computational fluid dynamics (CFD) using large-scale supercomputer applications is discussed. Formulational and computational requirements for the various governing equations, including the Euler and Navier-tokes approaches, are examined for typical problems including the viscous flow field solution about a complete aerospace vehicle. Recent computed results and experimental comparisons are given to highlight the presentation. The future of CFD associated with three-dimensional applications is found to be rapidly expanding across a broad front, including internal and external flows and flows across the entire speed regime.
The Fluid Dynamics Demo Kit: Part II
NASA Astrophysics Data System (ADS)
Underhill, Patrick; Fix, Hannah; Haines, Timothy; Prestridge, Kathy; Flack, Karen
2012-11-01
This talk will focus on the current contents and efforts building a fluid dynamics demonstration/experiment kit through the APS-DFD Mentoring and Outreach Committee and with funding from the APS DFD. The current experiments include predicting how far the water from a water gun will go, predicting how long a Heron's fountain will run, measuring the viscosity of corn syrup by measuring terminal velocity, and measuring the flow rate through a siphon. We will discuss the testing and development of these experiments and the results of field testing. Ideas for future experiments will also be discussed.
Computational fluid dynamics using CATIA created geometry
NASA Astrophysics Data System (ADS)
Gengler, Jeanne E.
1989-07-01
A method has been developed to link the geometry definition residing on a CAD/CAM system with a computational fluid dynamics (CFD) tool needed to evaluate aerodynamic designs and requiring the memory capacity of a supercomputer. Requirements for surfaces suitable for CFD analysis are discussed. Techniques for developing surfaces and verifying their smoothness are compared, showing the capability of the CAD/CAM system. The utilization of a CAD/CAM system to create a computational mesh is explained, and the mesh interaction with the geometry and input file preparation for the CFD analysis is discussed.
Expanding Participation in Fluid Dynamics Research
NASA Astrophysics Data System (ADS)
Tagg, Randall
2015-11-01
Two legacies provided by great scientists are scientific discoveries and more scientists. Is there a way that these impacts can be magnified? Examples using the Taylor-Couette experiment and other fluid dynamics problems will demonstrate that indeed more people can fruitfully engage in open and even bold investigation. Participants include high school students, teachers, undergraduates, artists, business developers and interested laypersons. With imagination, good training, and a suitable lab space, a special tribute can be given to those who mentor us by scaling up the breadth of their influence.
Distributed visualization for computational fluid dynamics
NASA Technical Reports Server (NTRS)
Sosoka, Don J.; Facca, Anthony A.
1992-01-01
Distributed concurrent visualization and computation in computational fluid dynamics (CFD) is not a new concept. Specialized applications such as Realtime Interactive Particle-tracer (RIP) and vendor specific tools like Distributed Graphics Language (DGL) have been in use for some time. This paper describes a current project underway at NASA Lewis Research Center to provide the CFD researcher with an easy method for incorporating distributed processing concepts into program development. Details on the FORTRAN capable interface to a set of network and visualization functions are presented along with some results from initial CFD case studies that employ these techniques.
Distributed visualization for computational fluid dynamics
NASA Astrophysics Data System (ADS)
Sosoka, Don J.; Facca, Anthony A.
1992-02-01
Distributed concurrent visualization and computation in computational fluid dynamics (CFD) is not a new concept. Specialized applications such as Realtime Interactive Particle-tracer (RIP) and vendor specific tools like Distributed Graphics Language (DGL) have been in use for some time. This paper describes a current project underway at NASA Lewis Research Center to provide the CFD researcher with an easy method for incorporating distributed processing concepts into program development. Details on the FORTRAN capable interface to a set of network and visualization functions are presented along with some results from initial CFD case studies that employ these techniques.
Yang, Chun; Tang, Dalin; Atluri, Satya
2011-01-01
Previously, we introduced a computational procedure based on three-dimensional meshless generalized finite difference (MGFD) method and serial magnetic resonance imaging (MRI) data to quantify patient-specific carotid atherosclerotic plaque growth functions and simulate plaque progression. Structure-only models were used in our previous report. In this paper, fluid-stricture interaction (FSI) was added to improve on prediction accuracy. One participating patient was scanned three times (T1, T2, and T3, at intervals of about 18 months) to obtain plaque progression data. Blood flow was assumed to laminar, Newtonian, viscous and incompressible. The Navier-Stokes equations with arbitrary Lagrangian-Eulerian (ALE) formulation were used as the governing equations. Plaque material was assumed to be uniform, homogeneous, isotropic, linear, and nearly incompressible. The linear elastic model was used. The 3D FSI plaque model was discretized and solved using a meshless generalized finite difference (GFD) method. Growth functions with a) morphology alone; b) morphology and plaque wall stress (PWS); morphology and flow shear stress (FSS), and d) morphology, PWS and FSS were introduced to predict future plaque growth based on previous time point data. Starting from the T2 plaque geometry, plaque progression was simulated by solving the FSI model and adjusting plaque geometry using plaque growth functions iteratively until T3 is reached. Numerically simulated plaque progression agreed very well with the target T3 plaque geometry with errors ranging from 8.62%, 7.22%, 5.77% and 4.39%, with the growth function including morphology, plaque wall stress and flow shear stress terms giving the best predictions. Adding flow shear stress term to the growth function improved the prediction error from 7.22% to 4.39%, a 40% improvement. We believe this is the first time 3D plaque progression FSI simulation based on multi-year patient-tracking data was reported. Serial MRI-based progression
Hallquist, J.O.
1981-01-01
A user's manual is provided for NIKE3D, a fully implicit three-dimensional finite element code for analyzing the large deformation static and dynamic response of inelastic solids. A contact-impact algorithm permits gaps and sliding along material interfaces. By a specialization of this algorithm, such interfaces can be rigidly tied to admit variable zoning without the need of transition regions. Spatial discretization is achieved by the use of 8-node constant pressure solid elements. Bandwidth minimization is optional. Post-processors for NIKE3D include GRAPE for plotting deformed shapes and stress contours and DYNAP for plotting time histories.
3D Spray Droplet Distributions in Sneezes
NASA Astrophysics Data System (ADS)
Techet, Alexandra; Scharfman, Barry; Bourouiba, Lydia
2015-11-01
3D spray droplet clouds generated during human sneezing are investigated using the Synthetic Aperture Feature Extraction (SAFE) method, which relies on light field imaging (LFI) and synthetic aperture (SA) refocusing computational photographic techniques. An array of nine high-speed cameras are used to image sneeze droplets and tracked the droplets in 3D space and time (3D + T). An additional high-speed camera is utilized to track the motion of the head during sneezing. In the SAFE method, the raw images recorded by each camera in the array are preprocessed and binarized, simplifying post processing after image refocusing and enabling the extraction of feature sizes and positions in 3D + T. These binary images are refocused using either additive or multiplicative methods, combined with thresholding. Sneeze droplet centroids, radii, distributions and trajectories are determined and compared with existing data. The reconstructed 3D droplet centroids and radii enable a more complete understanding of the physical extent and fluid dynamics of sneeze ejecta. These measurements are important for understanding the infectious disease transmission potential of sneezes in various indoor environments.
NASA Astrophysics Data System (ADS)
Morbidelli, Alessandro; Szulagyi, J.; Crida, A.; Tanigawa, T.; Lega, E.; Masset, F.; Bitsch, B.
2013-10-01
What sets the terminal mass of a giant planet once the latter enters into a runaway gas-accretion phase? The formation of a gap around the planet's orbit may be an answer, provided that the gap is wide and deep enough. A wide-spread idea is that this happens if the viscosity in the circumstellar disk is small, i.e. if planets form in the "dead zone". With 3D hydrodynamical simulations we study the formation of a gap in details. We find an interesting 4-step meridional loop in the gas dynamics: (1) the gas flows into the gap at the top layer of the disk; (2) then it falls towards the disk's midplane; (3) the planet keeps the gap open by pushing this infalling gas back into the disk; (4) the gas rises back to the disk's surface, which closes the loop. The gas flow in this loop is governed by the viscous timescale at the surface of the disk. It is generally accepted that the surface layer of the disk is MRI-active and viscous, even if a dead zone is present near the midplane. Thus, there should always be enough gas flowing into the gap for a Jupiter-mass planet to accrete at a fast rate, in absence of other regulation mechanisms. However, only a very small portion of the gas flowing into the gap is directly accreted by the planet. Most of the gas falling towards the planet forms a circumplanetary disk (CPD), due to angular momentum conservation. If the CPD is MRI-inactive, as suggested by Turner et al. (2010) and Fujii et al. (2011), it can act as a bottle-neck for planet accretion. We find that the main mechanism that allows the CPD to lose angular momentum is the torque exerted by the star via a spiral density wave. We compute that this promotes the accretion of 0.025% of the mass of the CPD per year, for a Jupiter mass planet at 5.2 AU, independent of viscosity. By balancing the pressure of the vertical inflow with that internal to the CPD, we estimate that the CPD should contain less than 1% of the planet's mass. This leads to a mass-doubling timescale for Jupiter
NASA Astrophysics Data System (ADS)
Bagaiev, Andrii; Ivanov, Vitaliy
2014-05-01
The Black Sea north-western shelf plays a key role in economics of the developing countries such as Ukraine due to food supply, invaluable recreational potential and variety of the relevant maritime shipping routes. On the other hand, a shallow flat shelf is mostly affected by anthropogenic pollution, eutrophication, hypoxia and harmful algae blooms. The research is focused on modeling the transport and transformation of PCBs (PolyChlorinated Biphenyls) because they are exceedingly toxic and highly resistant to degradation, hence cumulatively affect marine ecosystems. Being lipophilic compounds, PCBs demonstrate the distinguishing sorption/desorption activity taking part in the biogeochemical fluxes via the organic matter particles and sediments. In the framework of the research, the coastal in-situ data on PCB concentration in the water column and sediments are processed, visualized and analyzed. It is concluded that the main sources of PCBs are related to the Danube discharge and resuspension from the shallow-water sediments. Developed 3D numerical model is aimed at simulation of PCB contamination of the water column and sediment. The model integrates the full physics hydrodynamic block as well as modules, which describe detritus transport and transformation and PCB dynamics. Three state variables are simulated in PCB transport module: concentration in solute, on the settling particles of detritus and in the top layer of sediments. PCB adsorption/desorption on detritus; the reversible PCB fluxes at the water-sediment boundary; destruction of detritus are taken into consideration. Formalization of PCB deposition/resuspension in the sediments is adapted from Van Rijn's model of the suspended sediment transport. The model was spun up to reconstruct the short term scenario of the instantaneous PCB release from the St. George Arm of Danube. It has been shown that PCB transport on sinking detritus represents the natural buffer mechanism damping the spreading PCB