Advances in computational fluid dynamics solvers for modern computing environments
NASA Astrophysics Data System (ADS)
Hertenstein, Daniel; Humphrey, John R.; Paolini, Aaron L.; Kelmelis, Eric J.
2013-05-01
EM Photonics has been investigating the application of massively multicore processors to a key problem area: Computational Fluid Dynamics (CFD). While the capabilities of CFD solvers have continually increased and improved to support features such as moving bodies and adjoint-based mesh adaptation, the software architecture has often lagged behind. This has led to poor scaling as core counts reach the tens of thousands. In the modern High Performance Computing (HPC) world, clusters with hundreds of thousands of cores are becoming the standard. In addition, accelerator devices such as NVIDIA GPUs and Intel Xeon Phi are being installed in many new systems. It is important for CFD solvers to take advantage of the new hardware as the computations involved are well suited for the massively multicore architecture. In our work, we demonstrate that new features in NVIDIA GPUs are able to empower existing CFD solvers by example using AVUS, a CFD solver developed by the Air Force Research Labratory (AFRL) and the Volcanic Ash Advisory Center (VAAC). The effort has resulted in increased performance and scalability without sacrificing accuracy. There are many well-known codes in the CFD space that can benefit from this work, such as FUN3D, OVERFLOW, and TetrUSS. Such codes are widely used in the commercial, government, and defense sectors.
NASA Astrophysics Data System (ADS)
Gulamali, M. Y.; Saunders, J. H.; Jackson, M. D.; Pain, C. C.
2009-04-01
We present results from a new computational multi-fluid dynamics code, designed to model the transport of heat, mass and chemical species during flow of single or multiple immiscible fluid phases through porous media, including gravitational effects and compressibility. The model also captures the electrical phenomena which may arise through electrokinetic, electrochemical and electrothermal coupling. Building on the advanced computational technology of the Imperial College Ocean Model, this new development leads the way towards a complex multiphase code using arbitrary unstructured and adaptive meshes, and domains decomposed to run in parallel over a cluster of workstations or a dedicated parallel computer. These facilities will allow efficient and accurate modelling of multiphase flows which capture large- and small-scale transport phenomena, while preserving the important geology and/or surface topology to make the results physically meaningful and realistic. Applications include modelling of contaminant transport in aquifers, multiphase flow during hydrocarbon production, migration of carbon dioxide during sequestration, and evaluation of the design and safety of nuclear reactors. Simulations of the streaming potential resulting from multiphase flow in laboratory- and field-scale models demonstrate that streaming potential signals originate at fluid fronts, and at geologic boundaries where fluid saturation changes. This suggests that downhole measurements of streaming potential may be used to inform production strategies in oil and gas reservoirs. As water encroaches on an oil production well, the streaming-potential signal associated with the water front encompasses the well even when the front is up to 100 m away, so the potential measured at the well starts to change significantly relative to a distant reference electrode. Variations in the geometry of the encroaching water front could be characterized using an array of electrodes positioned along the well
NASA Technical Reports Server (NTRS)
Noor, Ahmed K. (Editor); Dwoyer, Douglas L. (Editor)
1988-01-01
Recent advances in computational structural and fluid dynamics are discussed in reviews and reports. Topics addressed include fluid-structure interaction and aeroelasticity, CFD techniques for reacting flows, micromechanics, stability and eigenproblems, probabilistic methods and chaotic dynamics, and perturbation and spectral methods. Consideration is given to finite-element, finite-volume, and boundary-element methods; adaptive methods; parallel processing machines and applications; and visualization, mesh generation, and AI interfaces.
NASA Technical Reports Server (NTRS)
1991-01-01
Advanced concepts in hardware, software and algorithms are being pursued for application in next generation space computers and for ground based analysis of space data. The research program focuses on massively parallel computation and neural networks, as well as optical processing and optical networking which are discussed under photonics. Also included are theoretical programs in neural and nonlinear science, and device development for magnetic and ferroelectric memories.
The coupling of fluids, dynamics, and controls on advanced architecture computers
NASA Technical Reports Server (NTRS)
Atwood, Christopher
1995-01-01
This grant provided for the demonstration of coupled controls, body dynamics, and fluids computations in a workstation cluster environment; and an investigation of the impact of peer-peer communication on flow solver performance and robustness. The findings of these investigations were documented in the conference articles.The attached publication, 'Towards Distributed Fluids/Controls Simulations', documents the solution and scaling of the coupled Navier-Stokes, Euler rigid-body dynamics, and state feedback control equations for a two-dimensional canard-wing. The poor scaling shown was due to serialized grid connectivity computation and Ethernet bandwidth limits. The scaling of a peer-to-peer communication flow code on an IBM SP-2 was also shown. The scaling of the code on the switched fabric-linked nodes was good, with a 2.4 percent loss due to communication of intergrid boundary point information. The code performance on 30 worker nodes was 1.7 (mu)s/point/iteration, or a factor of three over a Cray C-90 head. The attached paper, 'Nonlinear Fluid Computations in a Distributed Environment', documents the effect of several computational rate enhancing methods on convergence. For the cases shown, the highest throughput was achieved using boundary updates at each step, with the manager process performing communication tasks only. Constrained domain decomposition of the implicit fluid equations did not degrade the convergence rate or final solution. The scaling of a coupled body/fluid dynamics problem on an Ethernet-linked cluster was also shown.
NASA Astrophysics Data System (ADS)
Emelyanov, V. N.; Karpenko, A. G.; Volkov, K. N.
2015-06-01
Modern graphics processing units (GPU) provide architectures and new programming models that enable to harness their large processing power and to design computational fluid dynamics (CFD) simulations at both high performance and low cost. Possibilities of the use of GPUs for the simulation of internal fluid flows are discussed. The finite volume method is applied to solve three-dimensional (3D) unsteady compressible Euler and Navier-Stokes equations on unstructured meshes. Compute Inified Device Architecture (CUDA) technology is used for programming implementation of parallel computational algorithms. Solution of some fluid dynamics problems on GPUs is presented and approaches to optimization of the CFD code related to the use of different types of memory are discussed. Speedup of solution on GPUs with respect to the solution on central processor unit (CPU) is compared with the use of different meshes and different methods of distribution of input data into blocks. Performance measurements show that numerical schemes developed achieve 20 to 50 speedup on GPU hardware compared to CPU reference implementation. The results obtained provide promising perspective for designing a GPU-based software framework for applications in CFD.
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.
Advanced feedback control of indoor air quality using real-time computational fluid dynamics
Ratnam, E.; Campbell, T.; Bradley, R.
1998-10-01
This paper describes the partial implementation of a novel method of controlling indoor air quality (IAQ) for critical applications. The proposed method uses a numerical modeling technique known as computational fluid dynamics (CFD) for modeling the effect of variable ventilation rates for intelligent and rapid control of air contamination in space. This paper describes how a CFD model is made to run in real time linked to a feedback control loop. The technique was simulated in a graphical programming language. The simulation results indicate that a quasi-transient potential flow CFD model is a viable technique for feedback control of IAQ, and it is currently being implemented in an experimental validation.
Advanced computational techniques for incompressible/compressible fluid-structure interactions
NASA Astrophysics Data System (ADS)
Kumar, Vinod
2005-07-01
Fluid-Structure Interaction (FSI) problems are of great importance to many fields of engineering and pose tremendous challenges to numerical analyst. This thesis addresses some of the hurdles faced for both 2D and 3D real life time-dependent FSI problems with particular emphasis on parachute systems. The techniques developed here would help improve the design of parachutes and are of direct relevance to several other FSI problems. The fluid system is solved using the Deforming-Spatial-Domain/Stabilized Space-Time (DSD/SST) finite element formulation for the Navier-Stokes equations of incompressible and compressible flows. The structural dynamics solver is based on a total Lagrangian finite element formulation. Newton-Raphson method is employed to linearize the otherwise nonlinear system resulting from the fluid and structure formulations. The fluid and structural systems are solved in decoupled fashion at each nonlinear iteration. While rigorous coupling methods are desirable for FSI simulations, the decoupled solution techniques provide sufficient convergence in the time-dependent problems considered here. In this thesis, common problems in the FSI simulations of parachutes are discussed and possible remedies for a few of them are presented. Further, the effects of the porosity model on the aerodynamic forces of round parachutes are analyzed. Techniques for solving compressible FSI problems are also discussed. Subsequently, a better stabilization technique is proposed to efficiently capture and accurately predict the shocks in supersonic flows. The numerical examples simulated here require high performance computing. Therefore, numerical tools using distributed memory supercomputers with message passing interface (MPI) libraries were developed.
An advanced combustion research facility for validating computational fluid dynamics codes
NASA Astrophysics Data System (ADS)
Bullard, J. B.; Hurley, C. D.; Eccles, N. C.
1991-12-01
The Sector Combustion Rig (SCR), built to obtain experimental data which could be used to verify computational fluid dynamic programs and to investigate the formation and consumption of combustion products through a combustor, is described. This rig was designed to accommodate sectors of full size engine combustion chambers and to test them at real or simulated engine operating conditions. Changes made to improve the operating, measurement, and data handling capabilities of the rig as a result of experience from several years of operations are described together with some of the features which contribute to the uniqueness of the SCR. The SCR gas analysis system and instrumentation are described. Extracts from some results obtained during a recent program of tests on a Rolls-Royce RB211 combustor are given.
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.
Sittitavornwong, Somsak; Waite, Peter D.; Shih, Alan M.; Cheng, Gary C.; Koomullil, Roy; Ito, Yasushi; Cure, Joel K; Harding, Susan M.; Litaker, Mark
2013-01-01
Purpose Evaluate the soft tissue change of the upper airway after maxillomandibular advancement (MMA) by computational fluid dynamics (CFD). Materials and Methods Eight OSAS patients who required MMA were recruited into this study. All participants had pre- and post-operative computed tomography (CT) and underwent MMA by a single oral and maxillofacial surgeon. Upper airway CT data sets for these 8 participants were created with high-fidelity 3-D numerical models for computational fluid dynamics (CFD). The 3-D models were simulated and analyzed to study how changes in airway anatomy affects pressure effort required for normal breathing. Airway dimensions, skeletal changes, Apnea-Hypopnea Index (AHI), and pressure efforts of pre- and post-operative 3-D models were compared and correlations interpreted. Results After MMA, laminar and turbulent air flow was significantly decreased at every level of the airway. The cross-sectional areas at the soft palate and tongue base were significantly increased. Conclusions This study shows that MMA increases airway dimensions by the increasing the occipital base (Base) - pogonion (Pg) distance. An increase of the Base-Pg distance showed a significant correlation with an AHI improvement and a decreased pressure effort of the upper airway. Decreasing the pressure effort will decrease the breathing workload. This improves the condition of OSAS. PMID:23642544
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)
Chung, T. J.
2002-03-01
Computational fluid dynamics (CFD) techniques are used to study and solve complex fluid flow and heat transfer problems. This comprehensive text ranges from elementary concepts for the beginner to state-of-the-art CFD for the practitioner. It discusses and illustrates the basic principles of finite difference (FD), finite element (FE), and finite volume (FV) methods, with step-by-step hand calculations. Chapters go on to examine structured and unstructured grids, adaptive methods, computing techniques, and parallel processing. Finally, the author describes a variety of practical applications to problems in turbulence, reacting flows and combustion, acoustics, combined mode radiative heat transfer, multiphase flows, electromagnetic fields, and relativistic astrophysical flows. Students and practitioners--particularly in mechanical, aerospace, chemical, and civil engineering--will use this authoritative text to learn about and apply numerical techniques to the solution of fluid dynamics problems.
D.M. McEligot; K. G. Condie; G. E. McCreery; H. M. McIlroy; R. J. Pink; L.E. Hochreiter; J.D. Jackson; R.H. Pletcher; B.L. Smith; P. Vukoslavcevic; J.M. Wallace; J.Y. Yoo; J.S. Lee; S.T. Ro; S.O. Park
2005-10-01
Background: The ultimate goal of the study is the improvement of predictive methods for safety analyses and design of Generation IV reactor systems such as supercritical water reactors (SCWR) for higher efficiency, improved performance and operation, design simplification, enhanced safety and reduced waste and cost. The objective of this Korean / US / laboratory / university collaboration of coupled fundamental computational and experimental studies is to develop the supporting knowledge needed for improved predictive techniques for use in the technology development of Generation IV reactor concepts and their passive safety systems. The present study emphasizes SCWR concepts in the Generation IV program.
Computational fluid dynamics research
NASA Technical Reports Server (NTRS)
Chandra, Suresh; Jones, Kenneth; Hassan, Hassan; Mcrae, David Scott
1992-01-01
The focus of research in the computational fluid dynamics (CFD) area is two fold: (1) to develop new approaches for turbulence modeling so that high speed compressible flows can be studied for applications to entry and re-entry flows; and (2) to perform research to improve CFD algorithm accuracy and efficiency for high speed flows. Research activities, faculty and student participation, publications, and financial information are outlined.
NASA Astrophysics Data System (ADS)
Grujicic, M.; Bell, W. C.; Pandurangan, B.; Glomski, P. S.
2011-08-01
To combat the problem of traumatic brain injury (TBI), a signature injury of the current military conflicts, there is an urgent need to design head protection systems with superior blast/ballistic impact mitigation capabilities. Toward that end, the blast impact mitigation performance of an advanced combat helmet (ACH) head protection system equipped with polyurea suspension pads and subjected to two different blast peak pressure loadings has been investigated computationally. A fairly detailed (Lagrangian) finite-element model of a helmet/skull/brain assembly is first constructed and placed into an Eulerian air domain through which a single planar blast wave propagates. A combined Eulerian/Lagrangian transient nonlinear dynamics computational fluid/solid interaction analysis is next conducted in order to assess the extent of reduction in intra-cranial shock-wave ingress (responsible for TBI). This was done by comparing temporal evolutions of intra-cranial normal and shear stresses for the cases of an unprotected head and the helmet-protected head and by correlating these quantities with the three most common types of mild traumatic brain injury (mTBI), i.e., axonal damage, contusion, and subdural hemorrhage. The results obtained show that the ACH provides some level of protection against all investigated types of mTBI and that the level of protection increases somewhat with an increase in blast peak pressure. In order to rationalize the aforementioned findings, a shockwave propagation/reflection analysis is carried out for the unprotected head and helmet-protected head cases. The analysis qualitatively corroborated the results pertaining to the blast-mitigation efficacy of an ACH, but also suggested that there are additional shockwave energy dissipation phenomena which play an important role in the mechanical response of the unprotected/protected head to blast impact.
Computational Fluid Dynamics Library
Energy Science and Technology Software Center (ESTSC)
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
The use of computers for instruction in fluid dynamics
NASA Technical Reports Server (NTRS)
Watson, Val
1987-01-01
Applications for computers which improve instruction in fluid dynamics are examined. Computers can be used to illustrate three-dimensional flow fields and simple fluid dynamics mechanisms, to solve fluid dynamics problems, and for electronic sketching. The usefulness of computer applications is limited by computer speed, memory, and software and the clarity and field of view of the projected display. Proposed advances in personal computers which will address these limitations are discussed. Long range applications for computers in education are considered.
Poon, Eric K W; Hayat, Umair; Thondapu, Vikas; Ooi, Andrew S H; Ul Haq, Muhammad Asrar; Moore, Stephen; Foin, Nicolas; Tu, Shengxian; Chin, Cheng; Monty, Jason P; Marusic, Ivan; Barlis, Peter
2015-08-01
Percutaneous coronary intervention (PCI) has shown a high success rate in the treatment of coronary artery disease. The decision to perform PCI often relies on the cardiologist's visual interpretation of coronary lesions during angiography. This has inherent limitations, particularly due to the low resolution and two-dimensional nature of angiography. State-of-the-art modalities such as three-dimensional quantitative coronary angiography, optical coherence tomography and invasive fractional flow reserve (FFR) may improve clinicians' understanding of both the anatomical and physiological importance of coronary lesions. While invasive FFR is the gold standard technique for assessment of the haemodynamic significance of coronary lesions, recent studies have explored a surrogate for FFR derived solely from three-dimensional reconstruction of the invasive angiogram, and therefore eliminating need for a pressure wire. Utilizing advanced computational fluid dynamics research, this virtual fractional flow reserve (vFFR) has demonstrated reasonable correlation with invasive measurements and remains an intense area of ongoing study. However, at present, several limitations and computational fluid dynamic assumptions may preclude vFFR from widespread clinical use. This review demonstrates the tight integration of advanced three-dimensional imaging techniques and vFFR in assessing coronary artery disease, reviews the advantages and disadvantages of such techniques and attempts to provide a glimpse of how such advances may benefit future clinical decision-making during PCI. PMID:26247271
Dresser, Thomas J.; Dotson, Curtis L.; Fisher, Richard K.; Graf, Michael J.; Richmond, Marshall C.; Rakowski, Cynthia L.; Carlson, Thomas J.; Mathur, Dilip; Heisey, Paul G.
2007-10-10
This paper, the second part of a 2 part paper, discusses the use of Computational Fluid Dynamics (CFD) to gain further insight into the results of fish release testing conducted to evaluate the modifications made to upgrade Unit 8 at Wanapum Dam. Part 1 discusses the testing procedures and fish passage survival. Grant PUD is working with Voith Siemens Hydro (VSH) and the Pacific Northwest National Laboratory (PNNL) of DOE and Normandeau Associates in this evaluation. VSH has prepared the geometry for the CFD analysis corresponding to the four operating conditions tested with Unit 9, and the 5 operating conditions tested with Unit 8. Both VSH and PNNL have conducting CFD simulations of the turbine intakes, stay vanes, wicket gates, turbine blades and draft tube of the units. Primary objectives of the analyses were: • determine estimates of where the inserted fish passed the turbine components • determine the characteristics of the flow field along the paths calculated for pressure, velocity gradients and acceleration associated with fish sized bodies • determine the velocity gradients at the structures where fish to structure interaction is predicted. • correlate the estimated fish location of passage with observed injuries • correlate the calculated pressure and acceleration with the information recorded with the sensor fish • utilize the results of the analysis to further interpret the results of the testing. This paper discusses the results of the CFD analyses made to assist the interpretation of the fish test results.
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.
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.
Interfaces for Advanced Computing.
ERIC Educational Resources Information Center
Foley, James D.
1987-01-01
Discusses the coming generation of supercomputers that will have the power to make elaborate "artificial realities" that facilitate user-computer communication. Illustrates these technological advancements with examples of the use of head-mounted monitors which are connected to position and orientation sensors, and gloves that track finger and…
Finite element computational fluid mechanics
NASA Technical Reports Server (NTRS)
Baker, A. J.
1983-01-01
Finite element analysis as applied to the broad spectrum of computational fluid mechanics is analyzed. The finite element solution methodology is derived, developed, and applied directly to the differential equation systems governing classes of problems in fluid mechanics. The heat conduction equation is used to reveal the essence and elegance of finite element theory, including higher order accuracy and convergence. The algorithm is extended to the pervasive nonlinearity of the Navier-Stokes equations. A specific fluid mechanics problem class is analyzed with an even mix of theory and applications, including turbulence closure and the solution of turbulent flows.
NASA Technical Reports Server (NTRS)
Hassan, H. A.
1993-01-01
Two papers are included in this progress report. In the first, the compressible Navier-Stokes equations have been used to compute leading edge receptivity of boundary layers over parabolic cylinders. Natural receptivity at the leading edge was simulated and Tollmien-Schlichting waves were observed to develop in response to an acoustic disturbance, applied through the farfield boundary conditions. To facilitate comparison with previous work, all computations were carried out at a free stream Mach number of 0.3. The spatial and temporal behavior of the flowfields are calculated through the use of finite volume algorithms and Runge-Kutta integration. The results are dominated by strong decay of the Tollmien-Schlichting wave due to the presence of the mean flow favorable pressure gradient. The effects of numerical dissipation, forcing frequency, and nose radius are studied. The Strouhal number is shown to have the greatest effect on the unsteady results. In the second paper, a transition model for low-speed flows, previously developed by Young et al., which incorporates first-mode (Tollmien-Schlichting) disturbance information from linear stability theory has been extended to high-speed flow by incorporating the effects of second mode disturbances. The transition model is incorporated into a Reynolds-averaged Navier-Stokes solver with a one-equation turbulence model. Results using a variable turbulent Prandtl number approach demonstrate that the current model accurately reproduces available experimental data for first and second-mode dominated transitional flows. The performance of the present model shows significant improvement over previous transition modeling attempts.
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.
Computational fluid dynamics symposium on aeropropulsion
Not Available
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.
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.
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.
Tentner, Adrian; Lo, Simon; Ioilev, Andrey; Melnikov, Vladimir; Samigulin, Maskhud; Ustinenko, Vasily; Kozlov, Valentin
2006-07-01
A new code, CFD-BWR, is being developed for the simulation of two-phase flow phenomena inside a BWR fuel bundle. These phenomena include coolant phase changes and multiple flow regimes which directly influence the coolant interaction with fuel assembly and, ultimately, the reactor performance. CFD-BWR is a specialized module built on the foundation of the commercial CFD code STAR-CD which provides general two-phase flow modeling capabilities. New models describing the inter-phase mass, momentum, and energy transfer phenomena specific for BWRs have been developed and implemented in the CFD-BWR module. A set of experiments focused on two-phase flow and phase-change phenomena has been identified for the validation of the CFD-BWR code and results of two experiment analyses focused on the radial void distribution are presented. The close agreement between the computed results, the measured data and the correlation results provides confidence in the accuracy of the models. (authors)
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.
Computational fluid dynamics in cardiovascular disease.
Lee, Byoung-Kwon
2011-08-01
Computational fluid dynamics (CFD) is a mechanical engineering field for analyzing fluid flow, heat transfer, and associated phenomena, using computer-based simulation. CFD is a widely adopted methodology for solving complex problems in many modern engineering fields. The merit of CFD is developing new and improved devices and system designs, and optimization is conducted on existing equipment through computational simulations, resulting in enhanced efficiency and lower operating costs. However, in the biomedical field, CFD is still emerging. The main reason why CFD in the biomedical field has lagged behind is the tremendous complexity of human body fluid behavior. Recently, CFD biomedical research is more accessible, because high performance hardware and software are easily available with advances in computer science. All CFD processes contain three main components to provide useful information, such as pre-processing, solving mathematical equations, and post-processing. Initial accurate geometric modeling and boundary conditions are essential to achieve adequate results. Medical imaging, such as ultrasound imaging, computed tomography, and magnetic resonance imaging can be used for modeling, and Doppler ultrasound, pressure wire, and non-invasive pressure measurements are used for flow velocity and pressure as a boundary condition. Many simulations and clinical results have been used to study congenital heart disease, heart failure, ventricle function, aortic disease, and carotid and intra-cranial cerebrovascular diseases. With decreasing hardware costs and rapid computing times, researchers and medical scientists may increasingly use this reliable CFD tool to deliver accurate results. A realistic, multidisciplinary approach is essential to accomplish these tasks. Indefinite collaborations between mechanical engineers and clinical and medical scientists are essential. CFD may be an important methodology to understand the pathophysiology of the development and
AFDM: An Advanced Fluid-Dynamics Model
Bohl, W.R.; Parker, F.R. ); Wilhelm, D. . Inst. fuer Neutronenphysik und Reaktortechnik); Berthier, J. ); Goutagny, L. . Inst. de Protection et de Surete Nucleaire); Ninokata,
1990-09-01
AFDM, or the Advanced Fluid-Dynamics Model, is a computer code that investigates new approaches simulating the multiphase-flow fluid-dynamics aspects of severe accidents in fast reactors. The AFDM formalism starts with differential equations similar to those in the SIMMER-II code. These equations are modified to treat three velocity fields and supplemented with a variety of new models. The AFDM code has 12 topologies describing what material contacts are possible depending on the presence or absence of a given material in a computational cell, on the dominant liquid, and on the continuous phase. Single-phase, bubbly, churn-turbulent, cellular, and dispersed flow regimes are permitted for the pool situations modeled. Virtual mass terms are included for vapor in liquid-continuous flow. Interfacial areas between the continuous and discontinuous phases are convected to allow some tracking of phenomenological histories. Interfacial areas are also modified by models of nucleation, dynamic forces, turbulence, flashing, coalescence, and mass transfer. Heat transfer is generally treated using engineering correlations. Liquid-vapor phase transitions are handled with the nonequilibrium, heat-transfer-limited model, whereas melting and freezing processes are based on equilibrium considerations. Convection is treated using a fractional-step method of time integration, including a semi-implicit pressure iteration. A higher-order differencing option is provided to control numerical diffusion. The Los Alamos SESAME equation-of-state has been implemented using densities and temperatures as the independent variables. AFDM programming has vectorized all computational loops consistent with the objective of producing an exportable code. 24 refs., 4 figs.
Potential applications of computational fluid dynamics to biofluid analysis
NASA Technical Reports Server (NTRS)
Kwak, D.; Chang, J. L. C.; Rogers, S. E.; Rosenfeld, M.; Kwak, D.
1988-01-01
Computational fluid dynamics was developed to the stage where it has become an indispensable part of aerospace research and design. In view of advances made in aerospace applications, the computational approach can be used for biofluid mechanics research. Several flow simulation methods developed for aerospace problems are briefly discussed for potential applications to biofluids, especially to blood flow analysis.
Research on Computational Fluid Dynamics and Turbulence
NASA Technical Reports Server (NTRS)
1986-01-01
Preconditioning matrices for Chebyshev derivative operators in several space dimensions; the Jacobi matrix technique in computational fluid dynamics; and Chebyshev techniques for periodic problems are discussed.
Advanced Multigrid Solvers for Fluid Dynamics
NASA Technical Reports Server (NTRS)
Brandt, Achi
1999-01-01
The main objective of this project has been to support the development of multigrid techniques in computational fluid dynamics that can achieve "textbook multigrid efficiency" (TME), which is several orders of magnitude faster than current industrial CFD solvers. Toward that goal we have assembled a detailed table which lists every foreseen kind of computational difficulty for achieving it, together with the possible ways for resolving the difficulty, their current state of development, and references. We have developed several codes to test and demonstrate, in the framework of simple model problems, several approaches for overcoming the most important of the listed difficulties that had not been resolved before. In particular, TME has been demonstrated for incompressible flows on one hand, and for near-sonic flows on the other hand. General approaches were advanced for the relaxation of stagnation points and boundary conditions under various situations. Also, new algebraic multigrid techniques were formed for treating unstructured grid formulations. More details on all these are given below.
Advances in Computational Astrophysics
Calder, Alan C.; Kouzes, Richard T.
2009-03-01
I was invited to be the guest editor for a special issue of Computing in Science and Engineering along with a colleague from Stony Brook. This is the guest editors' introduction to a special issue of Computing in Science and Engineering. Alan and I have written this introduction and have been the editors for the 4 papers to be published in this special edition.
Computational fluid dynamics: Transition to design applications
NASA Technical Reports Server (NTRS)
Bradley, R. G.; Bhateley, I. C.; Howell, G. A.
1987-01-01
The development of aerospace vehicles, over the years, was an evolutionary process in which engineering progress in the aerospace community was based, generally, on prior experience and data bases obtained through wind tunnel and flight testing. Advances in the fundamental understanding of flow physics, wind tunnel and flight test capability, and mathematical insights into the governing flow equations were translated into improved air vehicle design. The modern day field of Computational Fluid Dynamics (CFD) is a continuation of the growth in analytical capability and the digital mathematics needed to solve the more rigorous form of the flow equations. Some of the technical and managerial challenges that result from rapidly developing CFD capabilites, some of the steps being taken by the Fort Worth Division of General Dynamics to meet these challenges, and some of the specific areas of application for high performance air vehicles are presented.
Advancing manufacturing through computational chemistry
Noid, D.W.; Sumpter, B.G.; Tuzun, R.E.
1995-12-31
The capabilities of nanotechnology and computational chemistry are reaching a point of convergence. New computer hardware and novel computational methods have created opportunities to test proposed nanometer-scale devices, investigate molecular manufacturing and model and predict properties of new materials. Experimental methods are also beginning to provide new capabilities that make the possibility of manufacturing various devices with atomic precision tangible. In this paper, we will discuss some of the novel computational methods we have used in molecular dynamics simulations of polymer processes, neural network predictions of new materials, and simulations of proposed nano-bearings and fluid dynamics in nano- sized devices.
Using Computers in Fluids Engineering Education
NASA Technical Reports Server (NTRS)
Benson, Thomas J.
1998-01-01
Three approaches for using computers to improve basic fluids engineering education are presented. The use of computational fluid dynamics solutions to fundamental flow problems is discussed. The use of interactive, highly graphical software which operates on either a modern workstation or personal computer is highlighted. And finally, the development of 'textbooks' and teaching aids which are used and distributed on the World Wide Web is described. Arguments for and against this technology as applied to undergraduate education are also discussed.
Applied Computational Fluid Dynamics at NASA Ames Research Center
NASA Technical Reports Server (NTRS)
Holst, Terry L.; Kwak, Dochan (Technical Monitor)
1994-01-01
The field of Computational Fluid Dynamics (CFD) has advanced to the point where it can now be used for many applications in fluid mechanics research and aerospace vehicle design. A few applications being explored at NASA Ames Research Center will be presented and discussed. The examples presented will range in speed from hypersonic to low speed incompressible flow applications. Most of the results will be from numerical solutions of the Navier-Stokes or Euler equations in three space dimensions for general geometry applications. Computational results will be used to highlight the presentation as appropriate. Advances in computational facilities including those associated with NASA's CAS (Computational Aerosciences) Project of the Federal HPCC (High Performance Computing and Communications) Program will be discussed. Finally, opportunities for future research will be presented and discussed. All material will be taken from non-sensitive, previously-published and widely-disseminated work.
NASA Astrophysics Data System (ADS)
Santini, Maurizio
2015-11-01
X-ray computed tomography (CT) is a well-known technique nowadays, since its first practical application by Sir. G. Hounsfield (Nobel price for medicine 1979) has continually benefited from optimising improvements, especially in medical applications. Indeed, also application of CT in various engineering research fields provides fundamental informations on a wide range of applications, considering that the technique is not destructive, allowing 3D visualization without perturbation of the analysed material. Nowadays, it is technologically possible to design and realize an equipment that achieve a micrometric resolution and even improve the sensibility in revealing differences in materials having very radiotransparency, allowing i.e. to distinguish between different fluids (with different density) or states of matter (like with two-phase flows). At the University of Bergamo, a prototype of an X-ray microCT system was developed since 2008, so being fully operative from 2012, with specific customizations for investigations in thermal-fluid dynamics and multiphase flow researches. A technical session held at the UIT International Conference in L'Aquila (Italy), at which this paper is referring, has presented some microCT fundamentals, to allow the audience to gain basics to follow the “fil-rouge” that links all the instrumentation developments, till the recent applications. Hereinafter are reported some applications currently developed at Bergamo University at the X-ray computed micro-tomography laboratory.
Nonlinear ship waves and computational fluid dynamics
MIYATA, Hideaki; ORIHARA, Hideo; SATO, Yohei
2014-01-01
Research works undertaken in the first author’s laboratory at the University of Tokyo over the past 30 years are highlighted. Finding of the occurrence of nonlinear waves (named Free-Surface Shock Waves) in the vicinity of a ship advancing at constant speed provided the start-line for the progress of innovative technologies in the ship hull-form design. Based on these findings, a multitude of the Computational Fluid Dynamic (CFD) techniques have been developed over this period, and are highlighted in this paper. The TUMMAC code has been developed for wave problems, based on a rectangular grid system, while the WISDAM code treats both wave and viscous flow problems in the framework of a boundary-fitted grid system. These two techniques are able to cope with almost all fluid dynamical problems relating to ships, including the resistance, ship’s motion and ride-comfort issues. Consequently, the two codes have contributed significantly to the progress in the technology of ship design, and now form an integral part of the ship-designing process. PMID:25311139
Advances and challenges in computational plasma science
NASA Astrophysics Data System (ADS)
Tang, W. M.
2005-02-01
Scientific simulation, which provides a natural bridge between theory and experiment, is an essential tool for understanding complex plasma behaviour. Recent advances in simulations of magnetically confined plasmas are reviewed in this paper, with illustrative examples, chosen from associated research areas such as microturbulence, magnetohydrodynamics and other topics. Progress has been stimulated, in particular, by the exponential growth of computer speed along with significant improvements in computer technology. The advances in both particle and fluid simulations of fine-scale turbulence and large-scale dynamics have produced increasingly good agreement between experimental observations and computational modelling. This was enabled by two key factors: (a) innovative advances in analytic and computational methods for developing reduced descriptions of physics phenomena spanning widely disparate temporal and spatial scales and (b) access to powerful new computational resources. Excellent progress has been made in developing codes for which computer run-time and problem-size scale well with the number of processors on massively parallel processors (MPPs). Examples include the effective usage of the full power of multi-teraflop (multi-trillion floating point computations per second) MPPs to produce three-dimensional, general geometry, nonlinear particle simulations that have accelerated advances in understanding the nature of turbulence self-regulation by zonal flows. These calculations, which typically utilized billions of particles for thousands of time-steps, would not have been possible without access to powerful present generation MPP computers and the associated diagnostic and visualization capabilities. In looking towards the future, the current results from advanced simulations provide great encouragement for being able to include increasingly realistic dynamics to enable deeper physics insights into plasmas in both natural and laboratory environments. This
Application of advanced computational technology to propulsion CFD
NASA Astrophysics Data System (ADS)
Szuch, John R.
The Internal Fluid Mechanics Division of the NASA Lewis Research Center is combining the key elements of computational fluid dynamics, aerothermodynamic experiments, and advanced computational technology to bring internal computational fluid dynamics (ICFM) to a state of practical application for aerospace propulsion system design. This paper presents an overview of efforts underway at NASA Lewis to advance and apply computational technology to ICFM. These efforts include the use of modern, software engineering principles for code development, the development of an AI-based user-interface for large codes, the establishment of a high-performance, data communications network to link ICFM researchers and facilities, and the application of parallel processing to speed up computationally intensive and/or time-critical ICFM problems. A multistage compressor flow physics program is cited as an example of efforts to use advanced computational technology to enhance a current NASA Lewis ICFM research program.
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.
Thermal Storage and Advanced Heat Transfer Fluids (Fact Sheet)
Not Available
2010-08-01
Fact sheet describing NREL CSP Program capabilities in the area of thermal storage and advanced heat transfer fluids: measuring thermophysical properties, measuring fluid flow and heat transfer, and simulating flow of thermal energy and fluid.
Verification and validation in computational fluid dynamics
NASA Astrophysics Data System (ADS)
Oberkampf, William L.; Trucano, Timothy G.
2002-04-01
Verification and validation (V&V) are the primary means to assess accuracy and reliability in computational simulations. This paper presents an extensive review of the literature in V&V in computational fluid dynamics (CFD), discusses methods and procedures for assessing V&V, and develops a number of extensions to existing ideas. The review of the development of V&V terminology and methodology points out the contributions from members of the operations research, statistics, and CFD communities. Fundamental issues in V&V are addressed, such as code verification versus solution verification, model validation versus solution validation, the distinction between error and uncertainty, conceptual sources of error and uncertainty, and the relationship between validation and prediction. The fundamental strategy of verification is the identification and quantification of errors in the computational model and its solution. In verification activities, the accuracy of a computational solution is primarily measured relative to two types of highly accurate solutions: analytical solutions and highly accurate numerical solutions. Methods for determining the accuracy of numerical solutions are presented and the importance of software testing during verification activities is emphasized. The fundamental strategy of validation is to assess how accurately the computational results compare with the experimental data, with quantified error and uncertainty estimates for both. This strategy employs a hierarchical methodology that segregates and simplifies the physical and coupling phenomena involved in the complex engineering system of interest. A hypersonic cruise missile is used as an example of how this hierarchical structure is formulated. The discussion of validation assessment also encompasses a number of other important topics. A set of guidelines is proposed for designing and conducting validation experiments, supported by an explanation of how validation experiments are different
AIR INGRESS ANALYSIS: COMPUTATIONAL FLUID DYNAMIC MODELS
Chang H. Oh; Eung S. Kim; Richard Schultz; Hans Gougar; David Petti; Hyung S. Kang
2010-08-01
The Idaho National Laboratory (INL), under the auspices of the U.S. Department of Energy, is performing research and development that focuses on key phenomena important during potential scenarios that may occur in very high temperature reactors (VHTRs). Phenomena Identification and Ranking Studies to date have ranked an air ingress event, following on the heels of a VHTR depressurization, as important with regard to core safety. Consequently, the development of advanced air ingress-related models and verification and validation data are a very high priority. Following a loss of coolant and system depressurization incident, air will enter the core of the High Temperature Gas Cooled Reactor through the break, possibly causing oxidation of the in-the core and reflector graphite structure. Simple core and plant models indicate that, under certain circumstances, the oxidation may proceed at an elevated rate with additional heat generated from the oxidation reaction itself. Under postulated conditions of fluid flow and temperature, excessive degradation of the lower plenum graphite can lead to a loss of structural support. Excessive oxidation of core graphite can also lead to the release of fission products into the confinement, which could be detrimental to a reactor safety. Computational fluid dynamic model developed in this study will improve our understanding of this phenomenon. This paper presents two-dimensional and three-dimensional CFD results for the quantitative assessment of the air ingress phenomena. A portion of results of the density-driven stratified flow in the inlet pipe will be compared with results of the experimental results.
"Nanotechnology Enabled Advanced Industrial Heat Transfer Fluids"
Dr. Ganesh Skandan; Dr. Amit Singhal; Mr. Kenneth Eberts; Mr. Damian Sobrevilla; Prof. Jerry Shan; Stephen Tse; Toby Rossmann
2008-06-12
ABSTRACT Nanotechnology Enabled Advanced industrial Heat Transfer Fluids” Improving the efficiency of Industrial Heat Exchangers offers a great opportunity to improve overall process efficiencies in diverse industries such as pharmaceutical, materials manufacturing and food processing. The higher efficiencies can come in part from improved heat transfer during both cooling and heating of the material being processed. Additionally, there is great interest in enhancing the performance and reducing the weight of heat exchangers used in automotives in order to increase fuel efficiency. The goal of the Phase I program was to develop nanoparticle containing heat transfer fluids (e.g., antifreeze, water, silicone and hydrocarbon-based oils) that are used in transportation and in the chemical industry for heating, cooling and recovering waste heat. Much work has been done to date at investigating the potential use of nanoparticle-enhanced thermal fluids to improve heat transfer in heat exchangers. In most cases the effect in a commercial heat transfer fluid has been marginal at best. In the Phase I work, we demonstrated that the thermal conductivity, and hence heat transfer, of a fluid containing nanoparticles can be dramatically increased when subjected to an external influence. The increase in thermal conductivity was significantly larger than what is predicted by commonly used thermal models for two-phase materials. Additionally, the surface of the nanoparticles was engineered so as to have a minimal influence on the viscosity of the fluid. As a result, a nanoparticle-laden fluid was successfully developed that can lead to enhanced heat transfer in both industrial and automotive heat exchangers
Center for Advanced Computational Technology
NASA Technical Reports Server (NTRS)
Noor, Ahmed K.
2000-01-01
The Center for Advanced Computational Technology (ACT) was established to serve as a focal point for diverse research activities pertaining to application of advanced computational technology to future aerospace systems. These activities include the use of numerical simulations, artificial intelligence methods, multimedia and synthetic environments, and computational intelligence, in the modeling, analysis, sensitivity studies, optimization, design and operation of future aerospace systems. The Center is located at NASA Langley and is an integral part of the School of Engineering and Applied Science of the University of Virginia. The Center has four specific objectives: 1) conduct innovative research on applications of advanced computational technology to aerospace systems; 2) act as pathfinder by demonstrating to the research community what can be done (high-potential, high-risk research); 3) help in identifying future directions of research in support of the aeronautical and space missions of the twenty-first century; and 4) help in the rapid transfer of research results to industry and in broadening awareness among researchers and engineers of the state-of-the-art in applications of advanced computational technology to the analysis, design prototyping and operations of aerospace and other high-performance engineering systems. In addition to research, Center activities include helping in the planning and coordination of the activities of a multi-center team of NASA and JPL researchers who are developing an intelligent synthesis environment for future aerospace systems; organizing workshops and national symposia; as well as writing state-of-the-art monographs and NASA special publications on timely topics.
A Computational Fluid Dynamics Algorithm on a Massively Parallel Computer
NASA Technical Reports Server (NTRS)
Jespersen, Dennis C.; Levit, Creon
1989-01-01
The discipline of computational fluid dynamics is demanding ever-increasing computational power to deal with complex fluid flow problems. We investigate the performance of a finite-difference computational fluid dynamics algorithm on a massively parallel computer, the Connection Machine. Of special interest is an implicit time-stepping algorithm; to obtain maximum performance from the Connection Machine, it is necessary to use a nonstandard algorithm to solve the linear systems that arise in the implicit algorithm. We find that the Connection Machine ran achieve very high computation rates on both explicit and implicit algorithms. The performance of the Connection Machine puts it in the same class as today's most powerful conventional supercomputers.
Recent advances in computational aerodynamics
NASA Astrophysics Data System (ADS)
Agarwal, Ramesh K.; Desse, Jerry E.
1991-04-01
The current state of the art in computational aerodynamics is described. Recent advances in the discretization of surface geometry, grid generation, and flow simulation algorithms have led to flowfield predictions for increasingly complex and realistic configurations. As a result, computational aerodynamics is emerging as a crucial enabling technology for the development and design of flight vehicles. Examples illustrating the current capability for the prediction of aircraft, launch vehicle and helicopter flowfields are presented. Unfortunately, accurate modeling of turbulence remains a major difficulty in the analysis of viscosity-dominated flows. In the future inverse design methods, multidisciplinary design optimization methods, artificial intelligence technology and massively parallel computer technology will be incorporated into computational aerodynamics, opening up greater opportunities for improved product design at substantially reduced costs.
Advanced flight computer. Special study
NASA Technical Reports Server (NTRS)
Coo, Dennis
1995-01-01
This report documents a special study to define a 32-bit radiation hardened, SEU tolerant flight computer architecture, and to investigate current or near-term technologies and development efforts that contribute to the Advanced Flight Computer (AFC) design and development. An AFC processing node architecture is defined. Each node may consist of a multi-chip processor as needed. The modular, building block approach uses VLSI technology and packaging methods that demonstrate a feasible AFC module in 1998 that meets that AFC goals. The defined architecture and approach demonstrate a clear low-risk, low-cost path to the 1998 production goal, with intermediate prototypes in 1996.
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.
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.
Vectorization of computer programs with applications to computational fluid dynamics
NASA Astrophysics Data System (ADS)
Gentzsch, W.
Techniques for adapting serial computer programs to the architecture of modern vector computers are presented and illustrated with examples, mainly from the field of computational fluid dynamics. The limitations of conventional computers are reviewed; the vector computers CRAY-1S and CDC-CYBER 205 are characterized; and chapters are devoted to vectorization of FORTRAN programs, sample-program vectorization on five different vector and parallel-architecture computers, restructuring of basic linear-algebra algorithms, iterative methods, vectorization of simple numerical algorithms, and fluid-dynamics vectorization on CRAY-1 (including an implicit beam and warming scheme, an implicit finite-difference method for laminar boundary-layer equations, the Galerkin method and a direct Monte Carlo simulation). Diagrams, charts, tables, and photographs are provided.
Engineering Fracking Fluids with Computer Simulation
NASA Astrophysics Data System (ADS)
Shaqfeh, Eric
2015-11-01
There are no comprehensive simulation-based tools for engineering the flows of viscoelastic fluid-particle suspensions in fully three-dimensional geometries. On the other hand, the need for such a tool in engineering applications is immense. Suspensions of rigid particles in viscoelastic fluids play key roles in many energy applications. For example, in oil drilling the ``drilling mud'' is a very viscous, viscoelastic fluid designed to shear-thin during drilling, but thicken at stoppage so that the ``cuttings'' can remain suspended. In a related application known as hydraulic fracturing suspensions of solids called ``proppant'' are used to prop open the fracture by pumping them into the well. It is well-known that particle flow and settling in a viscoelastic fluid can be quite different from that which is observed in Newtonian fluids. First, it is now well known that the ``fluid particle split'' at bifurcation cracks is controlled by fluid rheology in a manner that is not understood. Second, in Newtonian fluids, the presence of an imposed shear flow in the direction perpendicular to gravity (which we term a cross or orthogonal shear flow) has no effect on the settling of a spherical particle in Stokes flow (i.e. at vanishingly small Reynolds number). By contrast, in a non-Newtonian liquid, the complex rheological properties induce a nonlinear coupling between the sedimentation and shear flow. Recent experimental data have shown both the shear thinning and the elasticity of the suspending polymeric solutions significantly affects the fluid-particle split at bifurcations, as well as the settling rate of the solids. In the present work, we use the Immersed Boundary Method to develop computer simulations of viscoelastic flow in suspensions of spheres to study these problems. These simulations allow us to understand the detailed physical mechanisms for the remarkable physical behavior seen in practice, and actually suggest design rules for creating new fluid recipes.
Using artificial intelligence to control fluid flow computations
NASA Technical Reports Server (NTRS)
Gelsey, Andrew
1992-01-01
Computational simulation is an essential tool for the prediction of fluid flow. Many powerful simulation programs exist today. However, using these programs to reliably analyze fluid flow and other physical situations requires considerable human effort and expertise to set up a simulation, determine whether the output makes sense, and repeatedly run the simulation with different inputs until a satisfactory result is achieved. Automating this process is not only of considerable practical importance but will also significantly advance basic artificial intelligence (AI) research in reasoning about the physical world.
Computational fluid dynamics in a marine environment
NASA Technical Reports Server (NTRS)
Carlson, Arthur D.
1987-01-01
The introduction of the supercomputer and recent advances in both Reynolds averaged, and large eddy simulation fluid flow approximation techniques to the Navier-Stokes equations, have created a robust environment for the exploration of problems of interest to the Navy in general, and the Naval Underwater Systems Center in particular. The nature of problems that are of interest, and the type of resources needed for their solution are addressed. The goal is to achieve a good engineering solution to the fluid-structure interaction problem. It is appropriate to indicate that a paper by D. Champman played a major role in developing the interest in the approach discussed.
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.
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.
Graphics supercomputer for computational fluid dynamics research
NASA Astrophysics Data System (ADS)
Liaw, Goang S.
1994-11-01
The objective of this project is to purchase a state-of-the-art graphics supercomputer to improve the Computational Fluid Dynamics (CFD) research capability at Alabama A & M University (AAMU) and to support the Air Force research projects. A cutting-edge graphics supercomputer system, Onyx VTX, from Silicon Graphics Computer Systems (SGI), was purchased and installed. Other equipment including a desktop personal computer, PC-486 DX2 with a built-in 10-BaseT Ethernet card, a 10-BaseT hub, an Apple Laser Printer Select 360, and a notebook computer from Zenith were also purchased. A reading room has been converted to a research computer lab by adding some furniture and an air conditioning unit in order to provide an appropriate working environments for researchers and the purchase equipment. All the purchased equipment were successfully installed and are fully functional. Several research projects, including two existing Air Force projects, are being performed using these facilities.
Visualization of unsteady computational fluid dynamics
NASA Astrophysics Data System (ADS)
Haimes, Robert
1994-11-01
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.
A Generalized Fluid Formulation for Turbomachinery Computations
NASA Technical Reports Server (NTRS)
Merkle, Charles L.; Sankaran, Venkateswaran; Dorney, Daniel J.; Sondak, Douglas L.
2003-01-01
A generalized formulation of the equations of motion of an arbitrary fluid are developed for the purpose of defining a common iterative algorithm for computational procedures. The method makes use of the equations of motion in conservation form with separate pseudo-time derivatives used for defining the numerical flux for a Riemann solver and the convergence algorithm. The partial differential equations are complemented by an thermodynamic and caloric equations of state of a complexity necessary for describing the fluid. Representative solutions with a new code based on this general equation formulation are provided for three turbomachinery problems. The first uses air as a working fluid while the second uses gaseous oxygen in a regime in which real gas effects are of little importance. These nearly perfect gas computations provide a basis for comparing with existing perfect gas code computations. The third case is for the flow of liquid oxygen through a turbine where real gas effects are significant. Vortex shedding predictions with the LOX formulations reduce the discrepancy between perfect gas computations and experiment by approximately an order of magnitude, thereby verifying the real gas formulation as well as providing an effective case where its capabilities are necessary.
Spectral Methods for Computational Fluid Dynamics
NASA Technical Reports Server (NTRS)
Zang, T. A.; Streett, C. L.; Hussaini, M. Y.
1994-01-01
As a tool for large-scale computations in fluid dynamics, spectral methods were prophesized in 1944, born in 1954, virtually buried in the mid-1960's, resurrected in 1969, evangalized in the 1970's, and catholicized in the 1980's. The use of spectral methods for meteorological problems was proposed by Blinova in 1944 and the first numerical computations were conducted by Silberman (1954). By the early 1960's computers had achieved sufficient power to permit calculations with hundreds of degrees of freedom. For problems of this size the traditional way of computing the nonlinear terms in spectral methods was expensive compared with finite-difference methods. Consequently, spectral methods fell out of favor. The expense of computing nonlinear terms remained a severe drawback until Orszag (1969) and Eliasen, Machenauer, and Rasmussen (1970) developed the transform methods that still form the backbone of many large-scale spectral computations. The original proselytes of spectral methods were meteorologists involved in global weather modeling and fluid dynamicists investigating isotropic turbulence. The converts who were inspired by the successes of these pioneers remained, for the most part, confined to these and closely related fields throughout the 1970's. During that decade spectral methods appeared to be well-suited only for problems governed by ordinary diSerential eqllations or by partial differential equations with periodic boundary conditions. And, of course, the solution itself needed to be smooth. Some of the obstacles to wider application of spectral methods were: (1) poor resolution of discontinuous solutions; (2) inefficient implementation of implicit methods; and (3) drastic geometric constraints. All of these barriers have undergone some erosion during the 1980's, particularly the latter two. As a result, the applicability and appeal of spectral methods for computational fluid dynamics has broadened considerably. The motivation for the use of spectral
Computational fluid dynamics applications at McDonnel Douglas
NASA Technical Reports Server (NTRS)
Hakkinen, R. J.
1987-01-01
Representative examples are presented of applications and development of advanced Computational Fluid Dynamics (CFD) codes for aerodynamic design at the McDonnell Douglas Corporation (MDC). Transonic potential and Euler codes, interactively coupled with boundary layer computation, and solutions of slender-layer Navier-Stokes approximation are applied to aircraft wing/body calculations. An optimization procedure using evolution theory is described in the context of transonic wing design. Euler methods are presented for analysis of hypersonic configurations, and helicopter rotors in hover and forward flight. Several of these projects were accepted for access to the Numerical Aerodynamic Simulation (NAS) facility at the NASA-Ames Research Center.
Computational fluid dynamics applications at McDonnel Douglas
NASA Astrophysics Data System (ADS)
Hakkinen, R. J.
1987-03-01
Representative examples are presented of applications and development of advanced Computational Fluid Dynamics (CFD) codes for aerodynamic design at the McDonnell Douglas Corporation (MDC). Transonic potential and Euler codes, interactively coupled with boundary layer computation, and solutions of slender-layer Navier-Stokes approximation are applied to aircraft wing/body calculations. An optimization procedure using evolution theory is described in the context of transonic wing design. Euler methods are presented for analysis of hypersonic configurations, and helicopter rotors in hover and forward flight. Several of these projects were accepted for access to the Numerical Aerodynamic Simulation (NAS) facility at the NASA-Ames Research Center.
Application of computational fluid dynamics techniques to blood pumps.
Sukumar, R; Athavale, M M; Makhijani, V B; Przekwas, A J
1996-06-01
Present-day computational fluid dynamics (CFD) techniques can be used to analyze the behavior of fluid flow in a variety of pumps. CFD can be a powerful tool during the design stage for rapid virtual prototyping of different designs, analyzing performance parameters, and making design improvements. Computational flow solutions provide information such as the location and size of stagnation zones and the local shear rate. These parameters can be correlated to the extent of hemolysis and thrombus formation and are critical to the success of a blood pump. CFD-ACE, an advanced commercial CFD code developed by CFD Research Corporation, has been applied to fluid flows in rotary machines, such as axial flow pumps and inducers. Preprocessing and postprocessing tools for efficient grid generation and advanced graphical flow visualization are integrated seamlessly with CFD-ACE. The code has structured multiblock grid capability, non-Newtonian fluid treatment, a variety of turbulence models, and an Eulerian-Langrangian particle tracking model. CFD-ACE has been used successfully to study the flow characteristics in an axial flow blood pump. An unstructured flow solver that greatly automates the process of grid generation and speeds up the flow simulation is under development. PMID:8817950
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.
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.
Visualization of unsteady computational fluid dynamics
NASA Astrophysics Data System (ADS)
Haimes, Robert
1995-10-01
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.
Use of advanced computers for aerodynamic flow simulation
NASA Technical Reports Server (NTRS)
Bailey, F. R.; Ballhaus, W. F.
1980-01-01
The current and projected use of advanced computers for large-scale aerodynamic flow simulation applied to engineering design and research is discussed. The design use of mature codes run on conventional, serial computers is compared with the fluid research use of new codes run on parallel and vector computers. The role of flow simulations in design is illustrated by the application of a three dimensional, inviscid, transonic code to the Sabreliner 60 wing redesign. Research computations that include a more complete description of the fluid physics by use of Reynolds averaged Navier-Stokes and large-eddy simulation formulations are also presented. Results of studies for a numerical aerodynamic simulation facility are used to project the feasibility of design applications employing these more advanced three dimensional viscous flow simulations.
NASA Technical Reports Server (NTRS)
Mccroskey, W. J.
1986-01-01
The Fluid Dynamics Panel of AGARD arranged a Symposium on Applications of Computational Fluid Dynamics in Aeronautics, on 7 to 10 April 1986 in Aix-en-Provence, France. The purpose of the Symposium was to provide an assessment of the status of CFD in aerodynamic design and analysis, with an emphasis on emerging applications of advanced computational techniques to complex configurations. Sessions were devoted specifically to grid generation, methods for inviscid flows, calculations of viscous-inviscid interactions, and methods for solving the Navier-Stokes equations. The 31 papers presented at the meeting are published in AGARD Conference Proceedings CP-412 and are listed in the Appendix of this report. A brief synopsis of each paper and some general conclusions and recommendations are given.
Two-phase computational fluid dynamics
Rothe, P.H.
1991-07-26
The results of the project illustrate the feasibility of multiphase computerized fluid dynamics (CFD) software. Existing CFD software is capable of simulating particle fields, certain droplet fields, and certain free surface flows, and does so routinely in engineering applications. Stratified flows can be addressed by a multiphase CFD code, once one is developed with suitable capabilities. The groundwork for such a code has been laid. Calculations performed for stratified flows demonstrate the accuracy achievable and the convergence of the methodology. Extension of the stratified flow methodology to other segregated flows such as slug or annular faces no inherent limits. The research has commercial application in the development of multiphase CFD computer programs.
Shuttle rocket booster computational fluid dynamics
NASA Technical Reports Server (NTRS)
Chung, T. J.; Park, O. Y.
1988-01-01
Additional results and a revised and improved computer program listing from the shuttle rocket booster computational fluid dynamics formulations are presented. Numerical calculations for the flame zone of solid propellants are carried out using the Galerkin finite elements, with perturbations expanded to the zeroth, first, and second orders. The results indicate that amplification of oscillatory motions does indeed prevail in high frequency regions. For the second order system, the trend is similar to the first order system for low frequencies, but instabilities may appear at frequencies lower than those of the first order system. The most significant effect of the second order system is that the admittance is extremely oscillatory between moderately high frequency ranges.
Computational fluid dynamics of reaction injection moulding
NASA Astrophysics Data System (ADS)
Mateus, Artur; Mitchell, Geoffrey; Bártolo, Paulo
2012-09-01
The modern approach to the development of moulds for injection moulding (Reaction Injection Moulding - RIM, Thermoplastic Injection Moulding - TIM and others) differs from the conventional approach based exclusively on the designer's experience and hypotheses. The increasingly complexityof moulds and the requirement by the clients for the improvement of their quality, shorter delivery times, and lower prices, demand the development of novel approaches to developed optimal moulds and moulded parts. The development of more accurate computational tools is fundamental to optimize both, the injection mouldingprocesses and the design, quality and durability of the moulds. This paper focuses on the RIM process proposing a novel thermo-rheo-kinetic model. The proposed model was implemented in generalpurpose Computational Fluid Dynamics (CFD) software. The model enables to accurately describe both flow and curing stages. Simulation results were validated against experimental results.
Verification and Validation in Computational Fluid Dynamics
OBERKAMPF, WILLIAM L.; TRUCANO, TIMOTHY G.
2002-03-01
Verification and validation (V and V) are the primary means to assess accuracy and reliability in computational simulations. This paper presents an extensive review of the literature in V and V in computational fluid dynamics (CFD), discusses methods and procedures for assessing V and V, and develops a number of extensions to existing ideas. The review of the development of V and V terminology and methodology points out the contributions from members of the operations research, statistics, and CFD communities. Fundamental issues in V and V are addressed, such as code verification versus solution verification, model validation versus solution validation, the distinction between error and uncertainty, conceptual sources of error and uncertainty, and the relationship between validation and prediction. The fundamental strategy of verification is the identification and quantification of errors in the computational model and its solution. In verification activities, the accuracy of a computational solution is primarily measured relative to two types of highly accurate solutions: analytical solutions and highly accurate numerical solutions. Methods for determining the accuracy of numerical solutions are presented and the importance of software testing during verification activities is emphasized.
Utilizing parallel optimization in computational fluid dynamics
NASA Astrophysics Data System (ADS)
Kokkolaras, Michael
1998-12-01
General problems of interest in computational fluid dynamics are investigated by means of optimization. Specifically, in the first part of the dissertation, a method of optimal incremental function approximation is developed for the adaptive solution of differential equations. Various concepts and ideas utilized by numerical techniques employed in computational mechanics and artificial neural networks (e.g. function approximation and error minimization, variational principles and weighted residuals, and adaptive grid optimization) are combined to formulate the proposed method. The basis functions and associated coefficients of a series expansion, representing the solution, are optimally selected by a parallel direct search technique at each step of the algorithm according to appropriate criteria; the solution is built sequentially. In this manner, the proposed method is adaptive in nature, although a grid is neither built nor adapted in the traditional sense using a-posteriori error estimates. Variational principles are utilized for the definition of the objective function to be extremized in the associated optimization problems, ensuring that the problem is well-posed. Complicated data structures and expensive remeshing algorithms and systems solvers are avoided. Computational efficiency is increased by using low-order basis functions and concurrent computing. Numerical results and convergence rates are reported for a range of steady-state problems, including linear and nonlinear differential equations associated with general boundary conditions, and illustrate the potential of the proposed method. Fluid dynamics applications are emphasized. Conclusions are drawn by discussing the method's limitations, advantages, and possible extensions. The second part of the dissertation is concerned with the optimization of the viscous-inviscid-interaction (VII) mechanism in an airfoil flow analysis code. The VII mechanism is based on the concept of a transpiration velocity
Advanced numerics for multi-dimensional fluid flow calculations
NASA Technical Reports Server (NTRS)
Vanka, S. P.
1984-01-01
In recent years, there has been a growing interest in the development and use of mathematical models for the simulation of fluid flow, heat transfer and combustion processes in engineering equipment. The equations representing the multi-dimensional transport of mass, momenta and species are numerically solved by finite-difference or finite-element techniques. However despite the multiude of differencing schemes and solution algorithms, and the advancement of computing power, the calculation of multi-dimensional flows, especially three-dimensional flows, remains a mammoth task. The following discussion is concerned with the author's recent work on the construction of accurate discretization schemes for the partial derivatives, and the efficient solution of the set of nonlinear algebraic equations resulting after discretization. The present work has been jointly supported by the Ramjet Engine Division of the Wright Patterson Air Force Base, Ohio, and the NASA Lewis Research Center.
Advances in fluid resuscitation of hemorrhagic shock
Tremblay, Lorraine N.; Rizoli, Sandro B.; Brenneman, Frederick D.
2001-01-01
The optimal fluid for resuscitation in hemorrhagic shock would combine the volume expansion and oxygen-carrying capacity of blood without the need for cross-matching or the risk of disease transmission. Although the ideal fluid has yet to be discovered, current options are discussed in this review, including crystalloids, colloids, blood and blood substitutes. The future role of blood substitutes is not yet defined, but the potential advantages in trauma or elective surgery may prove to be enormous. PMID:11407826
Computational fluid dynamic modelling of cavitation
NASA Technical Reports Server (NTRS)
Deshpande, Manish; Feng, Jinzhang; Merkle, Charles L.
1993-01-01
Models in sheet cavitation in cryogenic fluids are developed for use in Euler and Navier-Stokes codes. The models are based upon earlier potential-flow models but enable the cavity inception point, length, and shape to be determined as part of the computation. In the present paper, numerical solutions are compared with experimental measurements for both pressure distribution and cavity length. Comparisons between models are also presented. The CFD model provides a relatively simple modification to an existing code to enable cavitation performance predictions to be included. The analysis also has the added ability of incorporating thermodynamic effects of cryogenic fluids into the analysis. Extensions of the current two-dimensional steady state analysis to three-dimensions and/or time-dependent flows are, in principle, straightforward although geometrical issues become more complicated. Linearized models, however offer promise of providing effective cavitation modeling in three-dimensions. This analysis presents good potential for improved understanding of many phenomena associated with cavity flows.
Domain decomposition methods in computational fluid dynamics
NASA Technical Reports Server (NTRS)
Gropp, William D.; Keyes, David E.
1992-01-01
The divide-and-conquer paradigm of iterative domain decomposition, or substructuring, has become a practical tool in computational fluid dynamic applications because of its flexibility in accommodating adaptive refinement through locally uniform (or quasi-uniform) grids, its ability to exploit multiple discretizations of the operator equations, and the modular pathway it provides towards parallelism. These features are illustrated on the classic model problem of flow over a backstep using Newton's method as the nonlinear iteration. Multiple discretizations (second-order in the operator and first-order in the preconditioner) and locally uniform mesh refinement pay dividends separately, and they can be combined synergistically. Sample performance results are included from an Intel iPSC/860 hypercube implementation.
Domain decomposition methods in computational fluid dynamics
NASA Technical Reports Server (NTRS)
Gropp, William D.; Keyes, David E.
1991-01-01
The divide-and-conquer paradigm of iterative domain decomposition, or substructuring, has become a practical tool in computational fluid dynamic applications because of its flexibility in accommodating adaptive refinement through locally uniform (or quasi-uniform) grids, its ability to exploit multiple discretizations of the operator equations, and the modular pathway it provides towards parallelism. These features are illustrated on the classic model problem of flow over a backstep using Newton's method as the nonlinear iteration. Multiple discretizations (second-order in the operator and first-order in the preconditioner) and locally uniform mesh refinement pay dividends separately, and they can be combined synergistically. Sample performance results are included from an Intel iPSC/860 hypercube implementation.
Computational fluid dynamics of airfoils and wings
NASA Technical Reports Server (NTRS)
Garabedian, P.; Mcfadden, G.
1982-01-01
It is pointed out that transonic flow is one of the fields where computational fluid dynamics turns out to be most effective. Codes for the design and analysis of supercritical airfoils and wings have become standard tools of the aircraft industry. The present investigation is concerned with mathematical models and theorems which account for some of the progress that has been made. The most successful aerodynamics codes are those for the analysis of flow at off-design conditions where weak shock waves appear. A major breakthrough was achieved by Murman and Cole (1971), who conceived of a retarded difference scheme which incorporates artificial viscosity to capture shocks in the supersonic zone. This concept has been used to develop codes for the analysis of transonic flow past a swept wing. Attention is given to the trailing edge and the boundary layer, entropy inequalities and wave drag, shockless airfoils, and the inverse swept wing code.
Nonlinear Fluid Computations in a Distributed Environment
NASA Technical Reports Server (NTRS)
Atwood, Christopher A.; Smith, Merritt H.
1995-01-01
The performance of a loosely and tightly-coupled workstation cluster is compared against a conventional vector supercomputer for the solution the Reynolds- averaged Navier-Stokes equations. The application geometries include a transonic airfoil, a tiltrotor wing/fuselage, and a wing/body/empennage/nacelle transport. Decomposition is of the manager-worker type, with solution of one grid zone per worker process coupled using the PVM message passing library. Task allocation is determined by grid size and processor speed, subject to available memory penalties. Each fluid zone is computed using an implicit diagonal scheme in an overset mesh framework, while relative body motion is accomplished using an additional worker process to re-establish grid communication.
Lectures series in computational fluid dynamics
NASA Technical Reports Server (NTRS)
Thompson, Kevin W.
1987-01-01
The lecture notes cover the basic principles of computational fluid dynamics (CFD). They are oriented more toward practical applications than theory, and are intended to serve as a unified source for basic material in the CFD field as well as an introduction to more specialized topics in artificial viscosity and boundary conditions. Each chapter in the test is associated with a videotaped lecture. The basic properties of conservation laws, wave equations, and shock waves are described. The duality of the conservation law and wave representations is investigated, and shock waves are examined in some detail. Finite difference techniques are introduced for the solution of wave equations and conservation laws. Stability analysis for finite difference approximations are presented. A consistent description of artificial viscosity methods are provided. Finally, the problem of nonreflecting boundary conditions are treated.
Domain decomposition algorithms and computation fluid dynamics
NASA Technical Reports Server (NTRS)
Chan, Tony F.
1988-01-01
In the past several years, domain decomposition was a very popular topic, partly motivated by the potential of parallelization. While a large body of theory and algorithms were developed for model elliptic problems, they are only recently starting to be tested on realistic applications. The application of some of these methods to two model problems in computational fluid dynamics are investigated. Some examples are two dimensional convection-diffusion problems and the incompressible driven cavity flow problem. The construction and analysis of efficient preconditioners for the interface operator to be used in the iterative solution of the interface solution is described. For the convection-diffusion problems, 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 discussed.
Artificial Intelligence In Computational Fluid Dynamics
NASA Technical Reports Server (NTRS)
Vogel, Alison Andrews
1991-01-01
Paper compares four first-generation artificial-intelligence (Al) software systems for computational fluid dynamics. Includes: Expert Cooling Fan Design System (EXFAN), PAN AIR Knowledge System (PAKS), grid-adaptation program MITOSIS, and Expert Zonal Grid Generation (EZGrid). Focuses on knowledge-based ("expert") software systems. Analyzes intended tasks, kinds of knowledge possessed, magnitude of effort required to codify knowledge, how quickly constructed, performances, and return on investment. On basis of comparison, concludes Al most successful when applied to well-formulated problems solved by classifying or selecting preenumerated solutions. In contrast, application of Al to poorly understood or poorly formulated problems generally results in long development time and large investment of effort, with no guarantee of success.
Computational fluid dynamics modelling in cardiovascular medicine
Morris, Paul D; Narracott, Andrew; von Tengg-Kobligk, Hendrik; Silva Soto, Daniel Alejandro; Hsiao, Sarah; Lungu, Angela; Evans, Paul; Bressloff, Neil W; Lawford, Patricia V; Hose, D Rodney; Gunn, Julian P
2016-01-01
This paper reviews the methods, benefits and challenges associated with the adoption and translation of computational fluid dynamics (CFD) modelling within cardiovascular medicine. CFD, a specialist area of mathematics and a branch of fluid mechanics, is used routinely in a diverse range of safety-critical engineering systems, which increasingly is being applied to the cardiovascular system. By facilitating rapid, economical, low-risk prototyping, CFD modelling has already revolutionised research and development of devices such as stents, valve prostheses, and ventricular assist devices. Combined with cardiovascular imaging, CFD simulation enables detailed characterisation of complex physiological pressure and flow fields and the computation of metrics which cannot be directly measured, for example, wall shear stress. CFD models are now being translated into clinical tools for physicians to use across the spectrum of coronary, valvular, congenital, myocardial and peripheral vascular diseases. CFD modelling is apposite for minimally-invasive patient assessment. Patient-specific (incorporating data unique to the individual) and multi-scale (combining models of different length- and time-scales) modelling enables individualised risk prediction and virtual treatment planning. This represents a significant departure from traditional dependence upon registry-based, population-averaged data. Model integration is progressively moving towards ‘digital patient’ or ‘virtual physiological human’ representations. When combined with population-scale numerical models, these models have the potential to reduce the cost, time and risk associated with clinical trials. The adoption of CFD modelling signals a new era in cardiovascular medicine. While potentially highly beneficial, a number of academic and commercial groups are addressing the associated methodological, regulatory, education- and service-related challenges. PMID:26512019
Computational fluid dynamics modelling in cardiovascular medicine.
Morris, Paul D; Narracott, Andrew; von Tengg-Kobligk, Hendrik; Silva Soto, Daniel Alejandro; Hsiao, Sarah; Lungu, Angela; Evans, Paul; Bressloff, Neil W; Lawford, Patricia V; Hose, D Rodney; Gunn, Julian P
2016-01-01
This paper reviews the methods, benefits and challenges associated with the adoption and translation of computational fluid dynamics (CFD) modelling within cardiovascular medicine. CFD, a specialist area of mathematics and a branch of fluid mechanics, is used routinely in a diverse range of safety-critical engineering systems, which increasingly is being applied to the cardiovascular system. By facilitating rapid, economical, low-risk prototyping, CFD modelling has already revolutionised research and development of devices such as stents, valve prostheses, and ventricular assist devices. Combined with cardiovascular imaging, CFD simulation enables detailed characterisation of complex physiological pressure and flow fields and the computation of metrics which cannot be directly measured, for example, wall shear stress. CFD models are now being translated into clinical tools for physicians to use across the spectrum of coronary, valvular, congenital, myocardial and peripheral vascular diseases. CFD modelling is apposite for minimally-invasive patient assessment. Patient-specific (incorporating data unique to the individual) and multi-scale (combining models of different length- and time-scales) modelling enables individualised risk prediction and virtual treatment planning. This represents a significant departure from traditional dependence upon registry-based, population-averaged data. Model integration is progressively moving towards 'digital patient' or 'virtual physiological human' representations. When combined with population-scale numerical models, these models have the potential to reduce the cost, time and risk associated with clinical trials. The adoption of CFD modelling signals a new era in cardiovascular medicine. While potentially highly beneficial, a number of academic and commercial groups are addressing the associated methodological, regulatory, education- and service-related challenges. PMID:26512019
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
Computational Fluid Dynamics of rising droplets
Wagner, Matthew; Francois, Marianne M.
2012-09-05
The main goal of this study is to perform simulations of droplet dynamics using Truchas, a LANL-developed computational fluid dynamics (CFD) software, and compare them to a computational study of Hysing et al.[IJNMF, 2009, 60:1259]. Understanding droplet dynamics is of fundamental importance in liquid-liquid extraction, a process used in the nuclear fuel cycle to separate various components. Simulations of a single droplet rising by buoyancy are conducted in two-dimensions. Multiple parametric studies are carried out to ensure the problem set-up is optimized. An Interface Smoothing Length (ISL) study and mesh resolution study are performed to verify convergence of the calculations. ISL is a parameter for the interface curvature calculation. Further, wall effects are investigated and checked against existing correlations. The ISL study found that the optimal ISL value is 2.5{Delta}x, with {Delta}x being the mesh cell spacing. The mesh resolution study found that the optimal mesh resolution is d/h=40, for d=drop diameter and h={Delta}x. In order for wall effects on terminal velocity to be insignificant, a conservative wall width of 9d or a nonconservative wall width of 7d can be used. The percentage difference between Hysing et al.[IJNMF, 2009, 60:1259] and Truchas for the velocity profiles vary from 7.9% to 9.9%. The computed droplet velocity and interface profiles are found in agreement with the study. The CFD calculations are performed on multiple cores, using LANL's Institutional High Performance Computing.
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
Advanced Heat Transfer and Thermal Storage Fluids
Moens, L.; Blake, D.
2005-01-01
The design of the next generation solar parabolic trough systems for power production will require the development of new thermal energy storage options with improved economics or operational characteristics. Current heat-transfer fluids such as VP-1?, which consists of a eutectic mixture of biphenyl and diphenyl oxide, allow a maximum operating temperature of ca. 300 C, a limit above which the vapor pressure would become too high and would require pressure-rated tanks. The use of VP-1? also suffers from a freezing point around 13 C that requires heating during cold periods. One of the goals for future trough systems is the use of heat-transfer fluids that can act as thermal storage media and that allow operating temperatures around 425 C combined with lower limits around 0 C. This paper presents an outline of our latest approach toward the development of such thermal storage fluids.
Computational Fluid Dynamics Program at NASA Ames Research Center
NASA Technical Reports Server (NTRS)
Holst, Terry L.
1989-01-01
The Computational Fluid Dynamics (CFD) Program at NASA Ames Research Center is reviewed and discussed. The technical elements of the CFD Program are listed and briefly discussed. These elements include algorithm research, research and pilot code development, scientific visualization, advanced surface representation, volume grid generation, and numerical optimization. Next, the discipline of CFD is briefly discussed and related to other areas of research at NASA Ames including experimental fluid dynamics, computer science research, computational chemistry, and numerical aerodynamic simulation. These areas combine with CFD to form a larger area of research, which might collectively be called computational technology. The ultimate goal of computational technology research at NASA Ames is to increase the physical understanding of the world in which we live, solve problems of national importance, and increase the technical capabilities of the aerospace community. Next, the major programs at NASA Ames that either use CFD technology or perform research in CFD are listed and discussed. Briefly, this list includes turbulent/transition physics and modeling, high-speed real gas flows, interdisciplinary research, turbomachinery demonstration computations, complete aircraft aerodynamics, rotorcraft applications, powered lift flows, high alpha flows, multiple body aerodynamics, and incompressible flow applications. Some of the individual problems actively being worked in each of these areas is listed to help define the breadth or extent of CFD involvement in each of these major programs. State-of-the-art examples of various CFD applications are presented to highlight most of these areas. The main emphasis of this portion of the presentation is on examples which will not otherwise be treated at this conference by the individual presentations. Finally, a list of principal current limitations and expected future directions is given.
Quantum chromodynamics with advanced computing
Kronfeld, Andreas S.; /Fermilab
2008-07-01
We survey results in lattice quantum chromodynamics from groups in the USQCD Collaboration. The main focus is on physics, but many aspects of the discussion are aimed at an audience of computational physicists.
Aerodynamic Analyses Requiring Advanced Computers, Part 1
NASA Technical Reports Server (NTRS)
1975-01-01
Papers are presented which deal with results of theoretical research on aerodynamic flow problems requiring the use of advanced computers. Topics discussed include: viscous flows, boundary layer equations, turbulence modeling and Navier-Stokes equations, and internal flows.
Bringing Advanced Computational Techniques to Energy Research
Mitchell, Julie C
2012-11-17
Please find attached our final technical report for the BACTER Institute award. BACTER was created as a graduate and postdoctoral training program for the advancement of computational biology applied to questions of relevance to bioenergy research.
Aerodynamic Analyses Requiring Advanced Computers, part 2
NASA Technical Reports Server (NTRS)
1975-01-01
Papers given at the conference present the results of theoretical research on aerodynamic flow problems requiring the use of advanced computers. Topics discussed include two-dimensional configurations, three-dimensional configurations, transonic aircraft, and the space shuttle.
Advanced designs for fluid flow visualization
NASA Technical Reports Server (NTRS)
1978-01-01
Research was carried out on existing and new designs for minimally intrusive measurement of flow fields in the Geophysical Fluid Flow Cell and the proposed Atmospheric General Circulation Experiment. The following topics are discussed: (1) identification and removal of foreign particles, (2) search for higher dielectric photochromic solutions, (3) selection of uv light source, (4) analysis of refractive techniques and (5) examination of fresnel lens applicability.
Cryogenic Fluid Management Technologies for Advanced Green Propulsion Systems
NASA Technical Reports Server (NTRS)
Motil, Susan M.; Meyer, Michael L.; Tucker, Stephen P.
2007-01-01
In support of the Exploration Vision for returning to the Moon and beyond, NASA and its partners are developing and testing critical cryogenic fluid propellant technologies that will meet the need for high performance propellants on long-term missions. Reliable knowledge of low-gravity cryogenic fluid management behavior is lacking and yet is critical in the areas of tank thermal and pressure control, fluid acquisition, mass gauging, and fluid transfer. Such knowledge can significantly reduce or even eliminate tank fluid boil-off losses for long term missions, reduce propellant launch mass and required on-orbit margins, and simplify vehicle operations. The Propulsion and Cryogenic Advanced Development (PCAD) Project is performing experimental and analytical evaluation of several areas within Cryogenic Fluid Management (CFM) to enable NASA's Exploration Vision. This paper discusses the status of the PCAD CFM technology focus areas relative to the anticipated CFM requirements to enable execution of the Vision for Space Exploration.
[Research activities in applied mathematics, fluid mechanics, and computer science
NASA Technical Reports Server (NTRS)
1995-01-01
This report summarizes research conducted at the Institute for Computer Applications in Science and Engineering in applied mathematics, fluid mechanics, and computer science during the period April 1, 1995 through September 30, 1995.
Research in Applied Mathematics, Fluid Mechanics and Computer Science
NASA Technical Reports Server (NTRS)
1999-01-01
This report summarizes research conducted at the Institute for Computer Applications in Science and Engineering in applied mathematics, fluid mechanics, and computer science during the period October 1, 1998 through March 31, 1999.
Computational fluid dynamics applications to improve crop production systems
Technology Transfer Automated Retrieval System (TEKTRAN)
Computational fluid dynamics (CFD), numerical analysis and simulation tools of fluid flow processes have emerged from the development stage and become nowadays a robust design tool. It is widely used to study various transport phenomena which involve fluid flow, heat and mass transfer, providing det...
Computational fluid dynamics of left ventricular ejection.
Georgiadis, J G; Wang, M; Pasipoularides, A
1992-01-01
The present investigation addresses the effects of simple geometric variations on intraventricular ejection dynamics, by methods from computational fluid dynamics. It is an early step in incorporating more and more relevant characteristics of the ejection process, such as a continuously changing irregular geometry, in numerical simulations. We consider the effects of varying chamber eccentricities and outflow valve orifice-to-inner surface area ratios on instantaneous ejection gradients along the axis of symmetry of the left ventricle. The equation of motion for the streamfunction was discretized and solved iteratively with specified boundary conditions on a boundary-fitted adaptive grid, using an alternating-direction-implicit (ADI) algorithm. The unsteady aspects of the ejection process were subsequently introduced into the numerical simulation. It was shown that for given chamber volume and outflow orifice area, higher chamber eccentricities require higher ejection pressure gradients for the same velocity and local acceleration values at the aortic anulus than more spherical shapes. This finding is referable to the rise in local acceleration effects across the outflow axis. This is to be contrasted with the case of outflow orifice stenosis, in which it was shown that it is the convective acceleration effects that are intensified strongly. PMID:1562106
Computational fluid dynamics in ventilation: Practical approach
NASA Astrophysics Data System (ADS)
Fontaine, J. R.
The potential of computation fluid dynamics (CFD) for conceiving ventilation systems is shown through the simulation of five practical cases. The following examples are considered: capture of pollutants on a surface treating tank equipped with a unilateral suction slot in the presence of a disturbing air draft opposed to suction; dispersion of solid aerosols inside fume cupboards; performances comparison of two general ventilation systems in a silkscreen printing workshop; ventilation of a large open painting area; and oil fog removal inside a mechanical engineering workshop. Whereas the two first problems are analyzed through two dimensional numerical simulations, the three other cases require three dimensional modeling. For the surface treating tank case, numerical results are compared to laboratory experiment data. All simulations are carried out using EOL, a CFD software specially devised to deal with air quality problems in industrial ventilated premises. It contains many analysis tools to interpret the results in terms familiar to the industrial hygienist. Much experimental work has been engaged to validate the predictions of EOL for ventilation flows.
Object Orientated Methods in Computational Fluid Dynamics.
NASA Astrophysics Data System (ADS)
Tabor, Gavin; Weller, Henry; Jasak, Hrvoje; Fureby, Christer
1997-11-01
We outline the aims of the FOAM code, a Finite Volume Computational Fluid Dynamics code written in C++, and discuss the use of Object Orientated Programming (OOP) methods to achieve these aims. The intention when writing this code was to make it as easy as possible to alter the modelling : this was achieved by making the top level syntax of the code as close as possible to conventional mathematical notation for tensors and partial differential equations. Object orientation enables us to define classes for both types of objects, and the operator overloading possible in C++ allows normal symbols to be used for the basic operations. The introduction of features such as automatic dimension checking of equations helps to enforce correct coding of models. We also discuss the use of OOP techniques such as data encapsulation and code reuse. As examples of the flexibility of this approach, we discuss the implementation of turbulence modelling using RAS and LES. The code is used to simulate turbulent flow for a number of test cases, including fully developed channel flow and flow around obstacles. We also demonstrate the use of the code for solving structures calculations and magnetohydrodynamics.
Advanced laptop and small personal computer technology
NASA Technical Reports Server (NTRS)
Johnson, Roger L.
1991-01-01
Advanced laptop and small personal computer technology is presented in the form of the viewgraphs. The following areas of hand carried computers and mobile workstation technology are covered: background, applications, high end products, technology trends, requirements for the Control Center application, and recommendations for the future.
Advanced Biomedical Computing Center (ABCC) | DSITP
The Advanced Biomedical Computing Center (ABCC), located in Frederick Maryland (MD), provides HPC resources for both NIH/NCI intramural scientists and the extramural biomedical research community. Its mission is to provide HPC support, to provide collaborative research, and to conduct in-house research in various areas of computational biology and biomedical research.
Advances in the microrheology of complex fluids
NASA Astrophysics Data System (ADS)
Waigh, Thomas Andrew
2016-07-01
New developments in the microrheology of complex fluids are considered. Firstly the requirements for a simple modern particle tracking microrheology experiment are introduced, the error analysis methods associated with it and the mathematical techniques required to calculate the linear viscoelasticity. Progress in microrheology instrumentation is then described with respect to detectors, light sources, colloidal probes, magnetic tweezers, optical tweezers, diffusing wave spectroscopy, optical coherence tomography, fluorescence correlation spectroscopy, elastic- and quasi-elastic scattering techniques, 3D tracking, single molecule methods, modern microscopy methods and microfluidics. New theoretical techniques are also reviewed such as Bayesian analysis, oversampling, inversion techniques, alternative statistical tools for tracks (angular correlations, first passage probabilities, the kurtosis, motor protein step segmentation etc), issues in micro/macro rheological agreement and two particle methodologies. Applications where microrheology has begun to make some impact are also considered including semi-flexible polymers, gels, microorganism biofilms, intracellular methods, high frequency viscoelasticity, comb polymers, active motile fluids, blood clots, colloids, granular materials, polymers, liquid crystals and foods. Two large emergent areas of microrheology, non-linear microrheology and surface microrheology are also discussed.
Advances in the microrheology of complex fluids.
Waigh, Thomas Andrew
2016-07-01
New developments in the microrheology of complex fluids are considered. Firstly the requirements for a simple modern particle tracking microrheology experiment are introduced, the error analysis methods associated with it and the mathematical techniques required to calculate the linear viscoelasticity. Progress in microrheology instrumentation is then described with respect to detectors, light sources, colloidal probes, magnetic tweezers, optical tweezers, diffusing wave spectroscopy, optical coherence tomography, fluorescence correlation spectroscopy, elastic- and quasi-elastic scattering techniques, 3D tracking, single molecule methods, modern microscopy methods and microfluidics. New theoretical techniques are also reviewed such as Bayesian analysis, oversampling, inversion techniques, alternative statistical tools for tracks (angular correlations, first passage probabilities, the kurtosis, motor protein step segmentation etc), issues in micro/macro rheological agreement and two particle methodologies. Applications where microrheology has begun to make some impact are also considered including semi-flexible polymers, gels, microorganism biofilms, intracellular methods, high frequency viscoelasticity, comb polymers, active motile fluids, blood clots, colloids, granular materials, polymers, liquid crystals and foods. Two large emergent areas of microrheology, non-linear microrheology and surface microrheology are also discussed. PMID:27245584
Advances and trends in computational structural mechanics
NASA Technical Reports Server (NTRS)
Noor, A. K.
1986-01-01
Recent developments in computational structural mechanics are reviewed with reference to computational needs for future structures technology, advances in computational models for material behavior, discrete element technology, assessment and control of numerical simulations of structural response, hybrid analysis, and techniques for large-scale optimization. Research areas in computational structural mechanics which have high potential for meeting future technological needs are identified. These include prediction and analysis of the failure of structural components made of new materials, development of computational strategies and solution methodologies for large-scale structural calculations, and assessment of reliability and adaptive improvement of response predictions.
Computing Properties Of Pure And Mixed Fluids
NASA Technical Reports Server (NTRS)
Fowler, J. R.; Hendricks, Robert C.
1993-01-01
GASPLUS created as two-part code: first designed for use with pure fluids and second designed for use with mixtures of fluids and phases. Offers routines for mathematical modeling of conditions of fluids in pumps, turbines, compressors and other machines. Other routines for calculating performance of para/ortho-hydrogen reactor and heat of para/normal-hydrogen reaction as well as unique convergence routine demonstrates engineering flavor of GASPLUS. Written in FORTRAN 77.
A parallel sparse algorithm targeting arterial fluid mechanics computations
NASA Astrophysics Data System (ADS)
Manguoglu, Murat; Takizawa, Kenji; Sameh, Ahmed H.; Tezduyar, Tayfun E.
2011-09-01
Iterative solution of large sparse nonsymmetric linear equation systems is one of the numerical challenges in arterial fluid-structure interaction computations. This is because the fluid mechanics parts of the fluid + structure block of the equation system that needs to be solved at every nonlinear iteration of each time step corresponds to incompressible flow, the computational domains include slender parts, and accurate wall shear stress calculations require boundary layer mesh refinement near the arterial walls. We propose a hybrid parallel sparse algorithm, domain-decomposing parallel solver (DDPS), to address this challenge. As the test case, we use a fluid mechanics equation system generated by starting with an arterial shape and flow field coming from an FSI computation and performing two time steps of fluid mechanics computation with a prescribed arterial shape change, also coming from the FSI computation. We show how the DDPS algorithm performs in solving the equation system and demonstrate the scalability of the algorithm.
Opportunities in computational mechanics: Advances in parallel computing
Lesar, R.A.
1999-02-01
In this paper, the authors will discuss recent advances in computing power and the prospects for using these new capabilities for studying plasticity and failure. They will first review the new capabilities made available with parallel computing. They will discuss how these machines perform and how well their architecture might work on materials issues. Finally, they will give some estimates on the size of problems possible using these computers.
Computational fluid dynamics for the CFBR : challenges that lie ahead /
Kashiwa, B. A.; Yang, Wen-ching,
2001-01-01
The potential of Computational Fluid Dynamics as a tool for design and analysis of the Circulating Fluidized Bed Reactor is considered. The ruminations are largely philosophical in nature, and are based mainly on experience. An assessment of where CFD may, or may not, be a helpful tool for developing the needed understanding, is furnished. To motivate this assessment, a clarification of what composes a CFD analysis is provided. Status of CFD usage in CFBR problems is summarized briefly. Some successes and failures of CFD in CFBR analysis are also discussed; this suggests a practical way to proceed toward the goal of adding CFD as a useful tool, to be used in combination with well-defined experiments, for CFBR needs. The conclusion is that there remains substantial hope that CFD could be very useful in this application. In order to make the hope a reality, nontrivial, and achievable, advances in multiphase flow theory must be made.
COMPUTATIONAL FLUID DYNAMICS MODELING ANALYSIS OF COMBUSTORS
Mathur, M.P.; Freeman, Mark; Gera, Dinesh
2001-11-06
In the current fiscal year FY01, several CFD simulations were conducted to investigate the effects of moisture in biomass/coal, particle injection locations, and flow parameters on carbon burnout and NO{sub x} inside a 150 MW GEEZER industrial boiler. Various simulations were designed to predict the suitability of biomass cofiring in coal combustors, and to explore the possibility of using biomass as a reburning fuel to reduce NO{sub x}. Some additional CFD simulations were also conducted on CERF combustor to examine the combustion characteristics of pulverized coal in enriched O{sub 2}/CO{sub 2} environments. Most of the CFD models available in the literature treat particles to be point masses with uniform temperature inside the particles. This isothermal condition may not be suitable for larger biomass particles. To this end, a stand alone program was developed from the first principles to account for heat conduction from the surface of the particle to its center. It is envisaged that the recently developed non-isothermal stand alone module will be integrated with the Fluent solver during next fiscal year to accurately predict the carbon burnout from larger biomass particles. Anisotropy in heat transfer in radial and axial will be explored using different conductivities in radial and axial directions. The above models will be validated/tested on various fullscale industrial boilers. The current NO{sub x} modules will be modified to account for local CH, CH{sub 2}, and CH{sub 3} radicals chemistry, currently it is based on global chemistry. It may also be worth exploring the effect of enriched O{sub 2}/CO{sub 2} environment on carbon burnout and NO{sub x} concentration. The research objective of this study is to develop a 3-Dimensional Combustor Model for Biomass Co-firing and reburning applications using the Fluent Computational Fluid Dynamics Code.
TOPICAL REVIEW: Advances and challenges in computational plasma science
NASA Astrophysics Data System (ADS)
Tang, W. M.; Chan, V. S.
2005-02-01
Scientific simulation, which provides a natural bridge between theory and experiment, is an essential tool for understanding complex plasma behaviour. Recent advances in simulations of magnetically confined plasmas are reviewed in this paper, with illustrative examples, chosen from associated research areas such as microturbulence, magnetohydrodynamics and other topics. Progress has been stimulated, in particular, by the exponential growth of computer speed along with significant improvements in computer technology. The advances in both particle and fluid simulations of fine-scale turbulence and large-scale dynamics have produced increasingly good agreement between experimental observations and computational modelling. This was enabled by two key factors: (a) innovative advances in analytic and computational methods for developing reduced descriptions of physics phenomena spanning widely disparate temporal and spatial scales and (b) access to powerful new computational resources. Excellent progress has been made in developing codes for which computer run-time and problem-size scale well with the number of processors on massively parallel processors (MPPs). Examples include the effective usage of the full power of multi-teraflop (multi-trillion floating point computations per second) MPPs to produce three-dimensional, general geometry, nonlinear particle simulations that have accelerated advances in understanding the nature of turbulence self-regulation by zonal flows. These calculations, which typically utilized billions of particles for thousands of time-steps, would not have been possible without access to powerful present generation MPP computers and the associated diagnostic and visualization capabilities. In looking towards the future, the current results from advanced simulations provide great encouragement for being able to include increasingly realistic dynamics to enable deeper physics insights into plasmas in both natural and laboratory environments. This
Physical aspects of computing the flow of a viscous fluid
NASA Technical Reports Server (NTRS)
Mehta, U. B.
1984-01-01
One of the main themes in fluid dynamics at present and in the future is going to be computational fluid dynamics with the primary focus on the determination of drag, flow separation, vortex flows, and unsteady flows. A computation of the flow of a viscous fluid requires an understanding and consideration of the physical aspects of the flow. This is done by identifying the flow regimes and the scales of fluid motion, and the sources of vorticity. Discussions of flow regimes deal with conditions of incompressibility, transitional and turbulent flows, Navier-Stokes and non-Navier-Stokes regimes, shock waves, and strain fields. Discussions of the scales of fluid motion consider transitional and turbulent flows, thin- and slender-shear layers, triple- and four-deck regions, viscous-inviscid interactions, shock waves, strain rates, and temporal scales. In addition, the significance and generation of vorticity are discussed. These physical aspects mainly guide computations of the flow of a viscous fluid.
Cerebrospinal Fluid Flow Studies and Recent Advancements.
Kelly, Erin J; Yamada, Shinya
2016-04-01
This article provides an overview of magnetic resonance imaging (MRI) techniques used to assess cerebrospinal fluid (CSF) movement in the central nervous system (CNS), including Phase-Contrast (PC), Time-Spatial Labeling Inversion Pulse, and simultaneous multi slice echo planar phase contrast imaging. These techniques have been used to assess CSF movement in the CNS under normal and pathophysiological situations. PC can quantitatively measure stroke volume in selected regions, particularly the aqueduct of Sylvius, as synchronized to the heartbeat. The PC is frequently used to investigate those patients with suspected normal pressure hydrocephalus and a Chiari I malformation. Time-Spatial Labeling Inversion Pulse, with high signal-to-noise ratio, captures motion of CSF anywhere in the CNS over a time period of up to 5 seconds. Variations of PC-MRI improved temporal resolution and included contributions from respiration. With non-invasive imaging such as these, more can be understood about CSF dynamics, especially with respect to the relative effects of cardiac and respiratory changes on CSF movement. PMID:27063659
Parallel Domain Decomposition Preconditioning for Computational Fluid Dynamics
NASA Technical Reports Server (NTRS)
Barth, Timothy J.; Chan, Tony F.; Tang, Wei-Pai; Kutler, Paul (Technical Monitor)
1998-01-01
This viewgraph presentation gives an overview of the parallel domain decomposition preconditioning for computational fluid dynamics. Details are given on some difficult fluid flow problems, stabilized spatial discretizations, and Newton's method for solving the discretized flow equations. Schur complement domain decomposition is described through basic formulation, simplifying strategies (including iterative subdomain and Schur complement solves, matrix element dropping, localized Schur complement computation, and supersparse computations), and performance evaluation.
Role of HPC in Advancing Computational Aeroelasticity
NASA Technical Reports Server (NTRS)
Guruswamy, Guru P.
2004-01-01
On behalf of the High Performance Computing and Modernization Program (HPCMP) and NASA Advanced Supercomputing Division (NAS) a study is conducted to assess the role of supercomputers on computational aeroelasticity of aerospace vehicles. The study is mostly based on the responses to a web based questionnaire that was designed to capture the nuances of high performance computational aeroelasticity, particularly on parallel computers. A procedure is presented to assign a fidelity-complexity index to each application. Case studies based on major applications using HPCMP resources are presented.
Development of a computational aero/fluids analysis system
NASA Technical Reports Server (NTRS)
Kelley, P. B.
1987-01-01
The Computational Aero/Fluids Analysis System (AFAS) provides the analytical capability to perform state-of-the-art computational analyses in two difficult fluid dynamics disciplines associated with the Space Shuttle program. This system provides the analysis tools and techniques for rapidly and efficiently accessing, analyzing, and reformulating the large and expanding external aerodynamic data base while also providing tools for complex fluid flow analyses of the SSME engine components. Both of these fluid flow disciplines, external aerodynamics and internal gasdynamics, required this capability to ensure that MSFC can respond in a timely manner as problems are encountered and operational changes are made in the Space Shuttle.
Role of computational fluid dynamics in unsteady aerodynamics for aeroelasticity
NASA Technical Reports Server (NTRS)
Guruswamy, Guru P.; Goorjian, Peter M.
1989-01-01
In the last two decades there have been extensive developments in computational unsteady transonic aerodynamics. Such developments are essential since the transonic regime plays an important role in the design of modern aircraft. Therefore, there has been a large effort to develop computational tools with which to accurately perform flutter analysis at transonic speeds. In the area of Computational Fluid Dynamics (CFD), unsteady transonic aerodynamics are characterized by the feature of modeling the motion of shock waves over aerodynamic bodies, such as wings. This modeling requires the solution of nonlinear partial differential equations. Most advanced codes such as XTRAN3S use the transonic small perturbation equation. Currently, XTRAN3S is being used for generic research in unsteady aerodynamics and aeroelasticity of almost full aircraft configurations. Use of Euler/Navier Stokes equations for simple typical sections has just begun. A brief history of the development of CFD for aeroelastic applications is summarized. The development of unsteady transonic aerodynamics and aeroelasticity are also summarized.
Eleventh Workshop for Computational Fluid Dynamic Applications in Rocket Propulsion
NASA Technical Reports Server (NTRS)
Williams, R. W. (Compiler)
1993-01-01
Conference publication includes 79 abstracts and presentations and 3 invited presentations given at the Eleventh Workshop for Computational Fluid Dynamic Applications in Rocket Propulsion held at George C. Marshall Space Flight Center, April 20-22, 1993. The purpose of the workshop is to discuss experimental and computational fluid dynamic activities in rocket propulsion. The workshop is an open meeting for government, industry, and academia. A broad number of topics are discussed including computational fluid dynamic methodology, liquid and solid rocket propulsion, turbomachinery, combustion, heat transfer, and grid generation.
Computational thermo-fluid analysis of a disk brake
NASA Astrophysics Data System (ADS)
Takizawa, Kenji; Tezduyar, Tayfun E.; Kuraishi, Takashi; Tabata, Shinichiro; Takagi, Hirokazu
2016-06-01
We present computational thermo-fluid analysis of a disk brake, including thermo-fluid analysis of the flow around the brake and heat conduction analysis of the disk. The computational challenges include proper representation of the small-scale thermo-fluid behavior, high-resolution representation of the thermo-fluid boundary layers near the spinning solid surfaces, and bringing the heat transfer coefficient (HTC) calculated in the thermo-fluid analysis of the flow to the heat conduction analysis of the spinning disk. The disk brake model used in the analysis closely represents the actual configuration, and this adds to the computational challenges. The components of the method we have developed for computational analysis of the class of problems with these types of challenges include the Space-Time Variational Multiscale method for coupled incompressible flow and thermal transport, ST Slip Interface method for high-resolution representation of the thermo-fluid boundary layers near spinning solid surfaces, and a set of projection methods for different parts of the disk to bring the HTC calculated in the thermo-fluid analysis. With the HTC coming from the thermo-fluid analysis of the flow around the brake, we do the heat conduction analysis of the disk, from the start of the breaking until the disk spinning stops, demonstrating how the method developed works in computational analysis of this complex and challenging problem.
Advanced Computed-Tomography Inspection System
NASA Technical Reports Server (NTRS)
Harris, Lowell D.; Gupta, Nand K.; Smith, Charles R.; Bernardi, Richard T.; Moore, John F.; Hediger, Lisa
1993-01-01
Advanced Computed Tomography Inspection System (ACTIS) is computed-tomography x-ray apparatus revealing internal structures of objects in wide range of sizes and materials. Three x-ray sources and adjustable scan geometry gives system unprecedented versatility. Gantry contains translation and rotation mechanisms scanning x-ray beam through object inspected. Distance between source and detector towers varied to suit object. System used in such diverse applications as development of new materials, refinement of manufacturing processes, and inspection of components.
Advances and Challenges in Computational Plasma Science
W.M. Tang; V.S. Chan
2005-01-03
Scientific simulation, which provides a natural bridge between theory and experiment, is an essential tool for understanding complex plasma behavior. Recent advances in simulations of magnetically-confined plasmas are reviewed in this paper with illustrative examples chosen from associated research areas such as microturbulence, magnetohydrodynamics, and other topics. Progress has been stimulated in particular by the exponential growth of computer speed along with significant improvements in computer technology.
Trends in computational capabilities for fluid dynamics
NASA Technical Reports Server (NTRS)
Peterson, V. L.
1985-01-01
Milestones in the development of computational aerodynamics are reviewed together with past, present, and future computer performance (speed and memory) trends. Factors influencing computer performance requirements for both steady and unsteady flow simulations are identified. Estimates of computer speed and memory that are required to calculate both inviscid and viscous, steady and unsteady flows about airfoils, wings, and simple wing body configurations are presented and compared to computer performance which is either currently available, or is expected to be available before the end of this decade. Finally, estimates of the amounts of computer time that are required to determine flutter boundaries of airfoils and wings at transonic Mach numbers are presented and discussed.
Trends in computational capabilities for fluid dynamics
NASA Technical Reports Server (NTRS)
Peterson, V. L.
1984-01-01
Milestones in the development of computational aerodynamics are reviewed together with past, present, and future computer performance (speed and memory) trends. Factors influencing computer performance requirements for both steady and unsteady flow simulations are identified. Estimates of computer speed and memory that are required to calculate both inviscid and viscous, steady and unsteady flows about airfoils, wings, and simple wing body configurations are presented and compared to computer performance which is either currently available, or is expected to be available before the end of this decade. Finally, estimates of the amounts of computer time that are required to determine flutter boundaries of airfoils and wings at transonic Mach numbers are presented and discussed.
Computational fluid dynamics modeling for emergency preparedness & response
Lee, R.L.; Albritton, J.R.; Ermak, D.L.; Kim, J.
1995-07-01
Computational fluid dynamics (CFD) has played an increasing role in the improvement of atmospheric dispersion modeling. This is because many dispersion models are now driven by meteorological fields generated from CFD models or, in numerical weather prediction`s terminology, prognostic models. Whereas most dispersion models typically involve one or a few scalar, uncoupled equations, the prognostic equations are a set of highly-coupled, nonlinear equations whose solution requires a significant level of computational power. Until recently, such computer power could be found only in CRAY-class supercomputers. Recent advances in computer hardware and software have enabled modestly-priced, high performance, workstations to exhibit the equivalent computation power of some mainframes. Thus desktop-class machines that were limited to performing dispersion calculations driven by diagnostic wind fields may now be used to calculate complex flows using prognostic CFD models. The Atmospheric Release and Advisory Capability (ARAC) program at Lawrence Livermore National Laboratory (LLNL) has, for the past several years, taken advantage of the improvements in hardware technology to develop a national emergency response capability based on executing diagnostic models on workstations. Diagnostic models that provide wind fields are, in general, simple to implement, robust and require minimal time for execution. Such models have been the cornerstones of the ARAC operational system for the past ten years. Kamada (1992) provides a review of diagnostic models and their applications to dispersion problems. However, because these models typically contain little physics beyond mass-conservation, their performance is extremely sensitive to the quantity and quality of input meteorological data and, in spite of their utility, can be applied with confidence to only modestly complex flows.
Advanced networks and computing in healthcare
Ackerman, Michael
2011-01-01
As computing and network capabilities continue to rise, it becomes increasingly important to understand the varied applications for using them to provide healthcare. The objective of this review is to identify key characteristics and attributes of healthcare applications involving the use of advanced computing and communication technologies, drawing upon 45 research and development projects in telemedicine and other aspects of healthcare funded by the National Library of Medicine over the past 12 years. Only projects publishing in the professional literature were included in the review. Four projects did not publish beyond their final reports. In addition, the authors drew on their first-hand experience as project officers, reviewers and monitors of the work. Major themes in the corpus of work were identified, characterizing key attributes of advanced computing and network applications in healthcare. Advanced computing and network applications are relevant to a range of healthcare settings and specialties, but they are most appropriate for solving a narrower range of problems in each. Healthcare projects undertaken primarily to explore potential have also demonstrated effectiveness and depend on the quality of network service as much as bandwidth. Many applications are enabling, making it possible to provide service or conduct research that previously was not possible or to achieve outcomes in addition to those for which projects were undertaken. Most notable are advances in imaging and visualization, collaboration and sense of presence, and mobility in communication and information-resource use. PMID:21486877
Advanced networks and computing in healthcare.
Ackerman, Michael; Locatis, Craig
2011-01-01
As computing and network capabilities continue to rise, it becomes increasingly important to understand the varied applications for using them to provide healthcare. The objective of this review is to identify key characteristics and attributes of healthcare applications involving the use of advanced computing and communication technologies, drawing upon 45 research and development projects in telemedicine and other aspects of healthcare funded by the National Library of Medicine over the past 12 years. Only projects publishing in the professional literature were included in the review. Four projects did not publish beyond their final reports. In addition, the authors drew on their first-hand experience as project officers, reviewers and monitors of the work. Major themes in the corpus of work were identified, characterizing key attributes of advanced computing and network applications in healthcare. Advanced computing and network applications are relevant to a range of healthcare settings and specialties, but they are most appropriate for solving a narrower range of problems in each. Healthcare projects undertaken primarily to explore potential have also demonstrated effectiveness and depend on the quality of network service as much as bandwidth. Many applications are enabling, making it possible to provide service or conduct research that previously was not possible or to achieve outcomes in addition to those for which projects were undertaken. Most notable are advances in imaging and visualization, collaboration and sense of presence, and mobility in communication and information-resource use. PMID:21486877
Advanced Algebra and Trigonometry: Supplemental Computer Units.
ERIC Educational Resources Information Center
Dotseth, Karen
A set of computer-oriented, supplemental activities is offered which can be used with a course in advanced algebra and trigonometry. The activities involve use of the BASIC programming language; it is assumed that the teacher is familiar with programming in BASIC. Students will learn some BASIC; however, the intent is not to develop proficient…
Computational Biology, Advanced Scientific Computing, and Emerging Computational Architectures
2007-06-27
This CRADA was established at the start of FY02 with $200 K from IBM and matching funds from DOE to support post-doctoral fellows in collaborative research between International Business Machines and Oak Ridge National Laboratory to explore effective use of emerging petascale computational architectures for the solution of computational biology problems. 'No cost' extensions of the CRADA were negotiated with IBM for FY03 and FY04.
Some Aspects of uncertainty in computational fluid dynamics results
NASA Technical Reports Server (NTRS)
Mehta, U. B.
1991-01-01
Uncertainties are inherent in computational fluid dynamics (CFD). These uncertainties need to be systematically addressed and managed. Sources of these uncertainty analysis are discussed. Some recommendations are made for quantification of CFD uncertainties. A practical method of uncertainty analysis is based on sensitivity analysis. When CFD is used to design fluid dynamic systems, sensitivity-uncertainty analysis is essential.
ADDRESSING ENVIRONMENTAL ENGINEERING CHALLENGES WITH COMPUTATIONAL FLUID DYNAMICS
This paper discusses the status and application of Computational Fluid Dynamics )CFD) models to address environmental engineering challenges for more detailed understanding of air pollutant source emissions, atmospheric dispersion and resulting human exposure. CFD simulations ...
Predictive Dynamic Security Assessment through Advanced Computing
Huang, Zhenyu; Diao, Ruisheng; Jin, Shuangshuang; Chen, Yousu
2014-11-30
Abstract— Traditional dynamic security assessment is limited by several factors and thus falls short in providing real-time information to be predictive for power system operation. These factors include the steady-state assumption of current operating points, static transfer limits, and low computational speed. This addresses these factors and frames predictive dynamic security assessment. The primary objective of predictive dynamic security assessment is to enhance the functionality and computational process of dynamic security assessment through the use of high-speed phasor measurements and the application of advanced computing technologies for faster-than-real-time simulation. This paper presents algorithms, computing platforms, and simulation frameworks that constitute the predictive dynamic security assessment capability. Examples of phasor application and fast computation for dynamic security assessment are included to demonstrate the feasibility and speed enhancement for real-time applications.
Deep Eutectic Salt Formulations Suitable as Advanced Heat Transfer Fluids
Raade, Justin; Roark, Thomas; Vaughn, John; Bradshaw, Robert
2013-07-22
Concentrating solar power (CSP) facilities are comprised of many miles of fluid-filled pipes arranged in large grids with reflective mirrors used to capture radiation from the sun. Solar radiation heats the fluid which is used to produce steam necessary to power large electricity generation turbines. Currently, organic, oil-based fluid in the pipes has a maximum temperature threshold of 400 °C, allowing for the production of electricity at approximately 15 cents per kilowatt hour. The DOE hopes to foster the development of an advanced heat transfer fluid that can operate within higher temperature ranges. The new heat transfer fluid, when used with other advanced technologies, could significantly decrease solar electricity cost. Lower costs would make solar thermal electricity competitive with gas and coal and would offer a clean, renewable source of energy. Molten salts exhibit many desirable heat transfer qualities within the range of the project objectives. Halotechnics developed advanced heat transfer fluids (HTFs) for application in solar thermal power generation. This project focused on complex mixtures of inorganic salts that exhibited a high thermal stability, a low melting point, and other favorable characteristics. A high-throughput combinatorial research and development program was conducted in order to achieve the project objective. Over 19,000 candidate formulations were screened. The workflow developed to screen various chemical systems to discover salt formulations led to mixtures suitable for use as HTFs in both parabolic trough and heliostat CSP plants. Furthermore, salt mixtures which will not interfere with fertilizer based nitrates were discovered. In addition for use in CSP, the discovered salt mixtures can be applied to electricity storage, heat treatment of alloys and other industrial processes.
Computational fluid dynamics modeling for emergency preparedness and response
Lee, R.L.; Albritton, J.R.; Ermak, D.L.; Kim, J.
1995-02-01
Computational fluid dynamics (CFD) has (CFD) has played an increasing in the improvement of atmospheric dispersion modeling. This is because many dispersion models are now driven by meteorological fields generated from CFD models or, in numerical weather prediction`s terminology, prognostic models. Whereas most dispersion models typically involve one or a few scalar, uncoupled equations, the prognostic equations are a set of highly-couple equations whose solution requires a significant level of computational power. Recent advances in computer hardware and software have enabled modestly-priced, high performance, workstations to exhibit the equivalent computation power of some mainframes. Thus desktop-class machines that were limited to performing dispersion calculations driven by diagnostic wind fields may now be used to calculate complex flows using prognostic CFD models. The Release and Advisory Capability (ARAC) program at Lawrence Livermore National Laboratory (LLNL) has, for the past several years, taken advantage of the improvements in hardware technology to develop a national emergency response capability based on executing diagnostic models on workstations. Diagnostic models that provide wind fields are, in general, simple to implement, robust and require minimal time for execution. Because these models typically contain little physics beyond mass-conservation, their performance is extremely sensitive to the quantity and quality of input meteorological data and, in spite of their utility, can be applied with confidence to only modestly complex flows. We are now embarking on a development program to incorporate prognostic models to generate, in real-time, the meteorological fields for the dispersion models. In contrast to diagnostic models, prognostic models are physically-based and are capable of incorporating many physical processes to treat highly complex flow scenarios.
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.
Computational fluid dynamics - Current capabilities and directions for the future
NASA Technical Reports Server (NTRS)
Kutler, Paul
1989-01-01
Computational fluid dynamics (CFD) has made great strides in the detailed simulation of complex fluid flows, including some of those not before understood. It is now being routinely applied to some rather complicated problems and starting to affect the design cycle of aerospace flight vehicles and their components. It is being used to complement, and is being complemented by, experimental studies. Several examples are presented in the paper to illustrate the current state of the art. Included is a discussion of the barriers to accomplishing the basic objective of numerical simulation. In addition, the directions for the future in the discipline of computational fluid dynamics are addressed.
NASA Astrophysics Data System (ADS)
Recent advances in experimental and computational fluid mechanics are discussed in a series of review essays. Topics addressed include transitions to complex flow in thermal convection, optimum hypersonic wings and wave riders, relativistic hydrodynamics, and wind-tunnel wall corrections for unsteady flow (steady wall adaptation and CFD techniques). Consideration is given to axisymmetric laminar interacting boundary layers, differential forms and fluid dynamics, breaking water waves, strong temperature gradients in turbulent wakes, and liquid-crystal 'blue' phases.
Advanced tomographic flow diagnostics for opaque multiphase fluids
Torczynski, J.R.; O`Hern, T.J.; Adkins, D.R.; Jackson, N.B.; Shollenberger, K.A.
1997-05-01
This report documents the work performed for the ``Advanced Tomographic Flow Diagnostics for Opaque Multiphase Fluids`` LDRD (Laboratory-Directed Research and Development) project and is presented as the fulfillment of the LDRD reporting requirement. Dispersed multiphase flows, particularly gas-liquid flows, are industrially important to the chemical and applied-energy industries, where bubble-column reactors are employed for chemical synthesis and waste treatment. Due to the large range of length scales (10{sup {minus}6}-10{sup 1}m) inherent in real systems, direct numerical simulation is not possible at present, so computational simulations are forced to use models of subgrid-scale processes, the accuracy of which strongly impacts simulation fidelity. The development and validation of such subgrid-scale models requires data sets at representative conditions. The ideal measurement techniques would provide spatially and temporally resolved full-field measurements of the distributions of all phases, their velocity fields, and additional associated quantities such as pressure and temperature. No technique or set of techniques is known that satisfies this requirement. In this study, efforts are focused on characterizing the spatial distribution of the phases in two-phase gas-liquid flow and in three-phase gas-liquid-solid flow. Due to its industrial importance, the bubble-column geometry is selected for diagnostics development and assessment. Two bubble-column testbeds are utilized: one at laboratory scale and one close to industrial scale. Several techniques for measuring the phase distributions at conditions of industrial interest are examined: level-rise measurements, differential-pressure measurements, bulk electrical impedance measurements, electrical bubble probes, x-ray tomography, gamma-densitometry tomography, and electrical impedance tomography.
Fluid Mechanics, Drag Reduction and Advanced Configuration Aeronautics
NASA Technical Reports Server (NTRS)
Bushnell, Dennis M.
2000-01-01
This paper discusses Advanced Aircraft configurational approaches across the speed range, which are either enabled, or greatly enhanced, by clever Flow Control. Configurations considered include Channel Wings with circulation control for VTOL (but non-hovering) operation with high cruise speed, strut-braced CTOL transports with wingtip engines and extensive ('natural') laminar flow control, a midwing double fuselage CTOL approach utilizing several synergistic methods for drag-due-to-lift reduction, a supersonic strut-braced configuration with order of twice the L/D of current approaches and a very advanced, highly engine flow-path-integrated hypersonic cruise machine. This paper indicates both the promise of synergistic flow control approaches as enablers for 'Revolutions' in aircraft performance and fluid mechanic 'areas of ignorance' which impede their realization and provide 'target-rich' opportunities for Fluids Research.
Advances in Computational Capabilities for Hypersonic Flows
NASA Technical Reports Server (NTRS)
Kumar, Ajay; Gnoffo, Peter A.; Moss, James N.; Drummond, J. Philip
1997-01-01
The paper reviews the growth and advances in computational capabilities for hypersonic applications over the period from the mid-1980's to the present day. The current status of the code development issues such as surface and field grid generation, algorithms, physical and chemical modeling, and validation is provided. A brief description of some of the major codes being used at NASA Langley Research Center for hypersonic continuum and rarefied flows is provided, along with their capabilities and deficiencies. A number of application examples are presented, and future areas of research to enhance accuracy, reliability, efficiency, and robustness of computational codes are discussed.
Fluid/Structure Interaction Studies of Aircraft Using High Fidelity Equations on Parallel Computers
NASA Technical Reports Server (NTRS)
Guruswamy, Guru; VanDalsem, William (Technical Monitor)
1994-01-01
Abstract Aeroelasticity which involves strong coupling of fluids, structures and controls is an important element in designing an aircraft. Computational aeroelasticity using low fidelity methods such as the linear aerodynamic flow equations coupled with the modal structural equations are well advanced. Though these low fidelity approaches are computationally less intensive, they are not adequate for the analysis of modern aircraft such as High Speed Civil Transport (HSCT) and Advanced Subsonic Transport (AST) which can experience complex flow/structure interactions. HSCT can experience vortex induced aeroelastic oscillations whereas AST can experience transonic buffet associated structural oscillations. Both aircraft may experience a dip in the flutter speed at the transonic regime. For accurate aeroelastic computations at these complex fluid/structure interaction situations, high fidelity equations such as the Navier-Stokes for fluids and the finite-elements for structures are needed. Computations using these high fidelity equations require large computational resources both in memory and speed. Current conventional super computers have reached their limitations both in memory and speed. As a result, parallel computers have evolved to overcome the limitations of conventional computers. This paper will address the transition that is taking place in computational aeroelasticity from conventional computers to parallel computers. The paper will address special techniques needed to take advantage of the architecture of new parallel computers. Results will be illustrated from computations made on iPSC/860 and IBM SP2 computer by using ENSAERO code that directly couples the Euler/Navier-Stokes flow equations with high resolution finite-element structural equations.
Advanced computational techniques for hypersonic propulsion
NASA Technical Reports Server (NTRS)
Povinelli, Louis A.
1989-01-01
Computational Fluid Dynamics (CFD) has played a major role in the resurgence of hypersonic flight, on the premise that numerical methods will allow performance of simulations at conditions for which no ground test capability exists. Validation of CFD methods is being established using the experimental data base available, which is below Mach 8. It is important, however, to realize the limitations involved in the extrapolation process as well as the deficiencies that exist in numerical methods at the present time. Current features of CFD codes are examined for application to propulsion system components. The shortcomings in simulation and modeling are identified and discussed.
Research Institute for Advanced Computer Science
NASA Technical Reports Server (NTRS)
Gross, Anthony R. (Technical Monitor); Leiner, Barry M.
2000-01-01
The Research Institute for Advanced Computer Science (RIACS) carries out basic research and technology development in computer science, in support of the National Aeronautics and Space Administration's missions. RIACS is located at the NASA Ames Research Center. It currently operates under a multiple year grant/cooperative agreement that began on October 1, 1997 and is up for renewal in the year 2002. Ames has been designated NASA's Center of Excellence in Information Technology. In this capacity, Ames is charged with the responsibility to build an Information Technology Research Program that is preeminent within NASA. RIACS serves as a bridge between NASA Ames and the academic community, and RIACS scientists and visitors work in close collaboration with NASA scientists. RIACS has the additional goal of broadening the base of researchers in these areas of importance to the nation's space and aeronautics enterprises. RIACS research focuses on the three cornerstones of information technology research necessary to meet the future challenges of NASA missions: (1) Automated Reasoning for Autonomous Systems. Techniques are being developed enabling spacecraft that will be self-guiding and self-correcting to the extent that they will require little or no human intervention. Such craft will be equipped to independently solve problems as they arise, and fulfill their missions with minimum direction from Earth; (2) Human-Centered Computing. Many NASA missions require synergy between humans and computers, with sophisticated computational aids amplifying human cognitive and perceptual abilities; (3) High Performance Computing and Networking. Advances in the performance of computing and networking continue to have major impact on a variety of NASA endeavors, ranging from modeling and simulation to data analysis of large datasets to collaborative engineering, planning and execution. In addition, RIACS collaborates with NASA scientists to apply information technology research to a
NASA Technical Reports Server (NTRS)
Byun, Chansup; Guruswamy, Guru P.; Kutler, Paul (Technical Monitor)
1994-01-01
In recent years significant advances have been made for parallel computers in both hardware and software. Now parallel computers have become viable tools in computational mechanics. Many application codes developed on conventional computers have been modified to benefit from parallel computers. Significant speedups in some areas have been achieved by parallel computations. For single-discipline use of both fluid dynamics and structural dynamics, computations have been made on wing-body configurations using parallel computers. However, only a limited amount of work has been completed in combining these two disciplines for multidisciplinary applications. The prime reason is the increased level of complication associated with a multidisciplinary approach. In this work, procedures to compute aeroelasticity on parallel computers using direct coupling of fluid and structural equations will be investigated for wing-body configurations. The parallel computer selected for computations is an Intel iPSC/860 computer which is a distributed-memory, multiple-instruction, multiple data (MIMD) computer with 128 processors. In this study, the computational efficiency issues of parallel integration of both fluid and structural equations will be investigated in detail. The fluid and structural domains will be modeled using finite-difference and finite-element approaches, respectively. Results from the parallel computer will be compared with those from the conventional computers using a single processor. This study will provide an efficient computational tool for the aeroelastic analysis of wing-body structures on MIMD type parallel computers.
AIR INGRESS ANALYSIS: PART 2 – COMPUTATIONAL FLUID DYNAMIC MODELS
Chang H. Oh; Eung S. Kim; Richard Schultz; Hans Gougar; David Petti; Hyung S. Kang
2011-01-01
The Idaho National Laboratory (INL), under the auspices of the U.S. Department of Energy, is performing research and development that focuses on key phenomena important during potential scenarios that may occur in very high temperature reactors (VHTRs). Phenomena Identification and Ranking Studies to date have ranked an air ingress event, following on the heels of a VHTR depressurization, as important with regard to core safety. Consequently, the development of advanced air ingress-related models and verification and validation data are a very high priority. Following a loss of coolant and system depressurization incident, air will enter the core of the High Temperature Gas Cooled Reactor through the break, possibly causing oxidation of the in-the core and reflector graphite structure. Simple core and plant models indicate that, under certain circumstances, the oxidation may proceed at an elevated rate with additional heat generated from the oxidation reaction itself. Under postulated conditions of fluid flow and temperature, excessive degradation of the lower plenum graphite can lead to a loss of structural support. Excessive oxidation of core graphite can also lead to the release of fission products into the confinement, which could be detrimental to a reactor safety. Computational fluid dynamic model developed in this study will improve our understanding of this phenomenon. This paper presents two-dimensional and three-dimensional CFD results for the quantitative assessment of the air ingress phenomena. A portion of results of the density-driven stratified flow in the inlet pipe will be compared with results of the experimental results.
The Role of Computer Assisted Fluid Balance in Critical Care
Ciccolella, Sergio A.; Halloran, Mark J.; Brimm, John E.; O'Hara, Michael R.
1978-01-01
Computational, reporting, and data base management needs along with growth in sophistication have propelled the application of computers in medicine. These elements are satisfying specific clinical needs in the fluid balance program design that was undertaken. Significant potential exists for extending the computer's intervention by using available transducing techniques to obtain information that is currently manually derived. Thus, the design currently satisfies the goal of maximizing information while minimizing labor intensive overhead and will continue to evolve in that direction.
Airborne Advanced Reconfigurable Computer System (ARCS)
NASA Technical Reports Server (NTRS)
Bjurman, B. E.; Jenkins, G. M.; Masreliez, C. J.; Mcclellan, K. L.; Templeman, J. E.
1976-01-01
A digital computer subsystem fault-tolerant concept was defined, and the potential benefits and costs of such a subsystem were assessed when used as the central element of a new transport's flight control system. The derived advanced reconfigurable computer system (ARCS) is a triple-redundant computer subsystem that automatically reconfigures, under multiple fault conditions, from triplex to duplex to simplex operation, with redundancy recovery if the fault condition is transient. The study included criteria development covering factors at the aircraft's operation level that would influence the design of a fault-tolerant system for commercial airline use. A new reliability analysis tool was developed for evaluating redundant, fault-tolerant system availability and survivability; and a stringent digital system software design methodology was used to achieve design/implementation visibility.
Application of computational fluid dynamics methods to improve thermal hydraulic code analysis
NASA Astrophysics Data System (ADS)
Sentell, Dennis Shannon, Jr.
A computational fluid dynamics code is used to model the primary natural circulation loop of a proposed small modular reactor for comparison to experimental data and best-estimate thermal-hydraulic code results. Recent advances in computational fluid dynamics code modeling capabilities make them attractive alternatives to the current conservative approach of coupled best-estimate thermal hydraulic codes and uncertainty evaluations. The results from a computational fluid dynamics analysis are benchmarked against the experimental test results of a 1:3 length, 1:254 volume, full pressure and full temperature scale small modular reactor during steady-state power operations and during a depressurization transient. A comparative evaluation of the experimental data, the thermal hydraulic code results and the computational fluid dynamics code results provides an opportunity to validate the best-estimate thermal hydraulic code's treatment of a natural circulation loop and provide insights into expanded use of the computational fluid dynamics code in future designs and operations. Additionally, a sensitivity analysis is conducted to determine those physical phenomena most impactful on operations of the proposed reactor's natural circulation loop. The combination of the comparative evaluation and sensitivity analysis provides the resources for increased confidence in model developments for natural circulation loops and provides for reliability improvements of the thermal hydraulic code.
Recent advances in computational actinoid chemistry.
Wang, Dongqi; van Gunsteren, Wilfred F; Chai, Zhifang
2012-09-01
We briefly review advances in computational actinoid (An) chemistry during the past ten years in regard to two issues: the geometrical and electronic structures, and reactions. The former addresses the An-O, An-C, and M-An (M is a metal atom including An) bonds in the actinoid molecular systems, including actinoid oxo and oxide species, actinoid-carbenoid, dinuclear and diatomic systems, and the latter the hydration and ligand exchange, the disproportionation, the oxidation, the reduction of uranyl, hydroamination, and the photolysis of uranium azide. Concerning their relevance to the electronic structures and reactions of actinoids and their importance in the development of an advanced nuclear fuel cycle, we also mentioned the work on actinoid carbides and nitrides, which have been proposed to be candidates of the next generation of nuclear fuel, and the oxidation of PuO(x), which is important to understand the speciation of actinoids in the environment, followed by a brief discussion on the urgent need for a heavier involvement of computational actinoid chemistry in developing advanced reprocessing protocols of spent nuclear fuel. The paper is concluded with an outlook. PMID:22777520
Computational fluid dynamics combustion analysis evaluation
NASA Technical Reports Server (NTRS)
Kim, Y. M.; Shang, H. M.; Chen, C. P.; Ziebarth, J. P.
1992-01-01
This study involves the development of numerical modelling in spray combustion. These modelling efforts are mainly motivated to improve the computational efficiency in the stochastic particle tracking method as well as to incorporate the physical submodels of turbulence, combustion, vaporization, and dense spray effects. The present mathematical formulation and numerical methodologies can be casted in any time-marching pressure correction methodologies (PCM) such as FDNS code and MAST code. A sequence of validation cases involving steady burning sprays and transient evaporating sprays will be included.
Computational fluid dynamics on a massively parallel computer
NASA Technical Reports Server (NTRS)
Jespersen, Dennis C.; Levit, Creon
1989-01-01
A finite difference code was implemented for the compressible Navier-Stokes equations on the Connection Machine, a massively parallel computer. The code is based on the ARC2D/ARC3D program and uses the implicit factored algorithm of Beam and Warming. The codes uses odd-even elimination to solve linear systems. Timings and computation rates are given for the code, and a comparison is made with a Cray XMP.
75 FR 43518 - Advanced Scientific Computing Advisory Committee; Meeting
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Computational Design of Advanced Nuclear Fuels
Savrasov, Sergey; Kotliar, Gabriel; Haule, Kristjan
2014-06-03
The objective of the project was to develop a method for theoretical understanding of nuclear fuel materials whose physical and thermophysical properties can be predicted from first principles using a novel dynamical mean field method for electronic structure calculations. We concentrated our study on uranium, plutonium, their oxides, nitrides, carbides, as well as some rare earth materials whose 4f eletrons provide a simplified framework for understanding complex behavior of the f electrons. We addressed the issues connected to the electronic structure, lattice instabilities, phonon and magnon dynamics as well as thermal conductivity. This allowed us to evaluate characteristics of advanced nuclear fuel systems using computer based simulations and avoid costly experiments.
ATCA for Machines-- Advanced Telecommunications Computing Architecture
Larsen, R.S.; /SLAC
2008-04-22
The Advanced Telecommunications Computing Architecture is a new industry open standard for electronics instrument modules and shelves being evaluated for the International Linear Collider (ILC). It is the first industrial standard designed for High Availability (HA). ILC availability simulations have shown clearly that the capabilities of ATCA are needed in order to achieve acceptable integrated luminosity. The ATCA architecture looks attractive for beam instruments and detector applications as well. This paper provides an overview of ongoing R&D including application of HA principles to power electronics systems.
A Textbook for a First Course in Computational Fluid Dynamics
NASA Technical Reports Server (NTRS)
Zingg, D. W.; Pulliam, T. H.; Nixon, David (Technical Monitor)
1999-01-01
This paper describes and discusses the textbook, Fundamentals of Computational Fluid Dynamics by Lomax, Pulliam, and Zingg, which is intended for a graduate level first course in computational fluid dynamics. This textbook emphasizes fundamental concepts in developing, analyzing, and understanding numerical methods for the partial differential equations governing the physics of fluid flow. Its underlying philosophy is that the theory of linear algebra and the attendant eigenanalysis of linear systems provides a mathematical framework to describe and unify most numerical methods in common use in the field of fluid dynamics. Two linear model equations, the linear convection and diffusion equations, are used to illustrate concepts throughout. Emphasis is on the semi-discrete approach, in which the governing partial differential equations (PDE's) are reduced to systems of ordinary differential equations (ODE's) through a discretization of the spatial derivatives. The ordinary differential equations are then reduced to ordinary difference equations (O(Delta)E's) using a time-marching method. This methodology, using the progression from PDE through ODE's to O(Delta)E's, together with the use of the eigensystems of tridiagonal matrices and the theory of O(Delta)E's, gives the book its distinctiveness and provides a sound basis for a deep understanding of fundamental concepts in computational fluid dynamics.
Computational Fluid Dynamics. [numerical methods and algorithm development
NASA Technical Reports Server (NTRS)
1992-01-01
This collection of papers was presented at the Computational Fluid Dynamics (CFD) Conference held at Ames Research Center in California on March 12 through 14, 1991. It is an overview of CFD activities at NASA Lewis Research Center. The main thrust of computational work at Lewis is aimed at propulsion systems. Specific issues related to propulsion CFD and associated modeling will also be presented. Examples of results obtained with the most recent algorithm development will also be presented.
Use of computational fluid dynamics in respiratory medicine.
Fernández Tena, Ana; Casan Clarà, Pere
2015-06-01
Computational Fluid Dynamics (CFD) is a computer-based tool for simulating fluid movement. The main advantages of CFD over other fluid mechanics studies include: substantial savings in time and cost, the analysis of systems or conditions that are very difficult to simulate experimentally (as is the case of the airways), and a practically unlimited level of detail. We used the Ansys-Fluent CFD program to develop a conducting airway model to simulate different inspiratory flow rates and the deposition of inhaled particles of varying diameters, obtaining results consistent with those reported in the literature using other procedures. We hope this approach will enable clinicians to further individualize the treatment of different respiratory diseases. PMID:25618456
Current capabilities and future directions in computational fluid dynamics
NASA Technical Reports Server (NTRS)
1986-01-01
A summary of significant findings is given, followed by specific recommendations for future directions of emphasis for computational fluid dynamics development. The discussion is organized into three application areas: external aerodynamics, hypersonics, and propulsion - and followed by a turbulence modeling synopsis.
Computational fluid dynamics development and validation at Bell Helicopter
NASA Astrophysics Data System (ADS)
Narramore, J. C.
1995-08-01
An overview of the development of the Computational Fluid Dynamics (CFD) methodology at Bell Helicopter Textron is given. As new technologies have been developed their functionality has been assessed by their ability to reproduce wind tunnel measurements in a timely manner. Examples of some of these correlation study results are provided.
Computer program for calculating thermodynamic and transport properties of fluids
NASA Technical Reports Server (NTRS)
Hendricks, R. C.; Braon, A. K.; Peller, I. C.
1975-01-01
Computer code has been developed to provide thermodynamic and transport properties of liquid argon, carbon dioxide, carbon monoxide, fluorine, helium, methane, neon, nitrogen, oxygen, and parahydrogen. Equation of state and transport coefficients are updated and other fluids added as new material becomes available.
DEVELOPMENT OF COMPUTER PROGRAM FOR FIRE SUPPRESSANT FLUID FLOW.
The objective of the project is to develop a computer code capable of predicting single and two phase hydrodynamic behavior of fire suppressant fluids during transport through piping systems. This new code will be able to predict pressure losses and flow rates for a wide variety ...
On the Use of Computers for Teaching Fluid Mechanics
NASA Technical Reports Server (NTRS)
Benson, Thomas J.
1994-01-01
Several approaches for improving the teaching of basic fluid mechanics using computers are presented. There are two objectives to these approaches: to increase the involvement of the student in the learning process and to present information to the student in a variety of forms. Items discussed include: the preparation of educational videos using the results of computational fluid dynamics (CFD) calculations, the analysis of CFD flow solutions using workstation based post-processing graphics packages, and the development of workstation or personal computer based simulators which behave like desk top wind tunnels. Examples of these approaches are presented along with observations from working with undergraduate co-ops. Possible problems in the implementation of these approaches as well as solutions to these problems are also discussed.
Advanced Scientific Computing Research Network Requirements
Bacon, Charles; Bell, Greg; Canon, Shane; Dart, Eli; Dattoria, Vince; Goodwin, Dave; Lee, Jason; Hicks, Susan; Holohan, Ed; Klasky, Scott; Lauzon, Carolyn; Rogers, Jim; Shipman, Galen; Skinner, David; Tierney, Brian
2013-03-08
The Energy Sciences Network (ESnet) is the primary provider of network connectivity for the U.S. Department of Energy (DOE) Office of Science (SC), the single largest supporter of basic research in the physical sciences in the United States. In support of SC programs, ESnet regularly updates and refreshes its understanding of the networking requirements of the instruments, facilities, scientists, and science programs that it serves. This focus has helped ESnet to be a highly successful enabler of scientific discovery for over 25 years. In October 2012, ESnet and the Office of Advanced Scientific Computing Research (ASCR) of the DOE SC organized a review to characterize the networking requirements of the programs funded by the ASCR program office. The requirements identified at the review are summarized in the Findings section, and are described in more detail in the body of the report.
Application of computational fluid mechanics to atmospheric pollution problems
NASA Technical Reports Server (NTRS)
Hung, R. J.; Liaw, G. S.; Smith, R. E.
1986-01-01
One of the most noticeable effects of air pollution on the properties of the atmosphere is the reduction in visibility. This paper reports the results of investigations of the fluid dynamical and microphysical processes involved in the formation of advection fog on aerosols from combustion-related pollutants, as condensation nuclei. The effects of a polydisperse aerosol distribution, on the condensation/nucleation processes which cause the reduction in visibility are studied. This study demonstrates how computational fluid mechanics and heat transfer modeling can be applied to simulate the life cycle of the atmosphereic pollution problems.
Computer program for computing the properties of seventeen fluids. [cryogenic liquids
NASA Technical Reports Server (NTRS)
Brennan, J. A.; Friend, D. G.; Arp, V. D.; Mccarty, R. D.
1992-01-01
The present study describes modifications and additions to the MIPROPS computer program for calculating the thermophysical properties of 17 fluids. These changes include adding new fluids, new properties, and a new interface to the program. The new program allows the user to select the input and output parameters and the units to be displayed for each parameter. Fluids added to the MIPROPS program are carbon dioxide, carbon monoxide, deuterium, helium, normal hydrogen, and xenon. The most recent modifications to the MIPROPS program are the addition of viscosity and thermal conductivity correlations for parahydrogen and the addition of the fluids normal hydrogen and xenon. The recently added interface considerably increases the program's utility.
76 FR 45786 - Advanced Scientific Computing Advisory Committee; Meeting
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Computational Fluid Dynamics Simulation of Dual Bell Nozzle Film Cooling
NASA Technical Reports Server (NTRS)
Braman, Kalen; Garcia, Christian; Ruf, Joseph; Bui, Trong
2015-01-01
Marshall Space Flight Center (MSFC) and Armstrong Flight Research Center (AFRC) are working together to advance the technology readiness level (TRL) of the dual bell nozzle concept. Dual bell nozzles are a form of altitude compensating nozzle that consists of two connecting bell contours. At low altitude the nozzle flows fully in the first, relatively lower area ratio, nozzle. The nozzle flow separates from the wall at the inflection point which joins the two bell contours. This relatively low expansion results in higher nozzle efficiency during the low altitude portion of the launch. As ambient pressure decreases with increasing altitude, the nozzle flow will expand to fill the relatively large area ratio second nozzle. The larger area ratio of the second bell enables higher Isp during the high altitude and vacuum portions of the launch. Despite a long history of theoretical consideration and promise towards improving rocket performance, dual bell nozzles have yet to be developed for practical use and have seen only limited testing. One barrier to use of dual bell nozzles is the lack of control over the nozzle flow transition from the first bell to the second bell during operation. A method that this team is pursuing to enhance the controllability of the nozzle flow transition is manipulation of the film coolant that is injected near the inflection between the two bell contours. Computational fluid dynamics (CFD) analysis is being run to assess the degree of control over nozzle flow transition generated via manipulation of the film injection. A cold flow dual bell nozzle, without film coolant, was tested over a range of simulated altitudes in 2004 in MSFC's nozzle test facility. Both NASA centers have performed a series of simulations of that dual bell to validate their computational models. Those CFD results are compared to the experimental results within this paper. MSFC then proceeded to add film injection to the CFD grid of the dual bell nozzle. A series of
TerraFERMA: Harnessing Advanced Computational Libraries in Earth Science
NASA Astrophysics Data System (ADS)
Wilson, C. R.; Spiegelman, M.; van Keken, P.
2012-12-01
Many important problems in Earth sciences can be described by non-linear coupled systems of partial differential equations. These "multi-physics" problems include thermo-chemical convection in Earth and planetary interiors, interactions of fluids and magmas with the Earth's mantle and crust and coupled flow of water and ice. These problems are of interest to a large community of researchers but are complicated to model and understand. Much of this complexity stems from the nature of multi-physics where small changes in the coupling between variables or constitutive relations can lead to radical changes in behavior, which in turn affect critical computational choices such as discretizations, solvers and preconditioners. To make progress in understanding such coupled systems requires a computational framework where multi-physics problems can be described at a high-level while maintaining the flexibility to easily modify the solution algorithm. Fortunately, recent advances in computational science provide a basis for implementing such a framework. Here we present the Transparent Finite Element Rapid Model Assembler (TerraFERMA), which leverages several advanced open-source libraries for core functionality. FEniCS (fenicsproject.org) provides a high level language for describing the weak forms of coupled systems of equations, and an automatic code generator that produces finite element assembly code. PETSc (www.mcs.anl.gov/petsc) provides a wide range of scalable linear and non-linear solvers that can be composed into effective multi-physics preconditioners. SPuD (amcg.ese.ic.ac.uk/Spud) is an application neutral options system that provides both human and machine-readable interfaces based on a single xml schema. Our software integrates these libraries and provides the user with a framework for exploring multi-physics problems. A single options file fully describes the problem, including all equations, coefficients and solver options. Custom compiled applications are
OPENING REMARKS: Scientific Discovery through Advanced Computing
NASA Astrophysics Data System (ADS)
Strayer, Michael
2006-01-01
Good morning. Welcome to SciDAC 2006 and Denver. I share greetings from the new Undersecretary for Energy, Ray Orbach. Five years ago SciDAC was launched as an experiment in computational science. The goal was to form partnerships among science applications, computer scientists, and applied mathematicians to take advantage of the potential of emerging terascale computers. This experiment has been a resounding success. SciDAC has emerged as a powerful concept for addressing some of the biggest challenges facing our world. As significant as these successes were, I believe there is also significance in the teams that achieved them. In addition to their scientific aims these teams have advanced the overall field of computational science and set the stage for even larger accomplishments as we look ahead to SciDAC-2. I am sure that many of you are expecting to hear about the results of our current solicitation for SciDAC-2. I’m afraid we are not quite ready to make that announcement. Decisions are still being made and we will announce the results later this summer. Nearly 250 unique proposals were received and evaluated, involving literally thousands of researchers, postdocs, and students. These collectively requested more than five times our expected budget. This response is a testament to the success of SciDAC in the community. In SciDAC-2 our budget has been increased to about 70 million for FY 2007 and our partnerships have expanded to include the Environment and National Security missions of the Department. The National Science Foundation has also joined as a partner. These new partnerships are expected to expand the application space of SciDAC, and broaden the impact and visibility of the program. We have, with our recent solicitation, expanded to turbulence, computational biology, and groundwater reactive modeling and simulation. We are currently talking with the Department’s applied energy programs about risk assessment, optimization of complex systems - such
A computational model for doctoring fluid films in gravure printing
NASA Astrophysics Data System (ADS)
Hariprasad, Daniel S.; Grau, Gerd; Schunk, P. Randall; Tjiptowidjojo, Kristianto
2016-04-01
The wiping, or doctoring, process in gravure printing presents a fundamental barrier to resolving the micron-sized features desired in printed electronics applications. This barrier starts with the residual fluid film left behind after wiping, and its importance grows as feature sizes are reduced, especially as the feature size approaches the thickness of the residual fluid film. In this work, various mechanical complexities are considered in a computational model developed to predict the residual fluid film thickness. Lubrication models alone are inadequate, and deformation of the doctor blade body together with elastohydrodynamic lubrication must be considered to make the model predictive of experimental trends. Moreover, model results demonstrate that the particular form of the wetted region of the blade has a significant impact on the model's ability to reproduce experimental measurements.
Numerical computational of fluid flow through a detached retina
NASA Astrophysics Data System (ADS)
Jiann, Lim Yeou; Ismail, Zuhaila; Shafie, Sharidan; Fitt, Alistair
2015-02-01
In this paper, a phenomenon of fluid flow through a detached retina is studied. Rhegmatogeneous retinal detachment happens when vitreous humour flow through a detached retina. The exact mechanism of Rhegmatogeneous retinal detachment is complex and remains incomplete. To understand the fluid flow, a paradigm mathematical model is developed and is approximated by the lubrication theory. The numerical results of the velocity profile and pressure distribution are computed by using Finite Element Method. The effects of fluid mechanical on the retinal detachment is discussed and analyzed. Based on the analysis, it is found that the retinal detachment deformation affects the pressure distribution. It is important to comprehend the development of the retinal detachment so that a new treatment method can be developed.
Computational fluid dynamics at NASA Ames Research Center
NASA Technical Reports Server (NTRS)
Kutler, Paul
1989-01-01
Computational fluid dynamics (CFD) has made great strides in the detailed simulation of complex fluid flows, including the fluid physics of flows heretofore not understood. It is now being routinely applied to some rather complicated problems, and starting to impact the design cycle of aerospace flight vehicles and their components. In addition, it is being used to complement, and is being complemented by, experimental studies. In the present paper, some major elements of contemporary CFD research, such as code validation, turbulence physics, and hypersonic flows are discussed, along with a review of the principal pacing items that currently govern CFD. Several examples of pioneering CFD research are presented to illustrate the current state of the art. Finally, prospects for the future development and application of CFD are suggested.
Progress and future directions in computational fluid dynamics
NASA Technical Reports Server (NTRS)
Kutler, Paul; Gross, Anthony R.
1988-01-01
Computational fluid dynamics (CFD) has made great strides in the detailed simulation of complex fluid flows, including the fluid physics of flows heretofore not understood. It is now being routinely applied to some rather complicated problems, and starting to impact the design cycle of aerospace vehicles and their components. In addition, it is being used to complement and is being complemented by experimental studies. In this paper some major elements of contemporary CFD research, such as code validation, turbulence physics, and hypersonic flows are discussed, along with a review of the principal pacing items that currently govern CFD. Several examples are presented to illustrate the current state of the art. Finally, prospects for the future of the development and application of CFD are suggested.
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).
75 FR 57742 - Advanced Scientific Computing Advisory Committee
Federal Register 2010, 2011, 2012, 2013, 2014
2010-09-22
... Advanced Scientific Computing Advisory Committee AGENCY: Department of Energy, Office of Science. ACTION... Scientific Computing Advisory Committee (ASCAC). Federal Advisory Committee Act (Pub. L. 92-463, 86 Stat. 770...: Melea Baker, Office of Advanced Scientific Computing Research; SC-21/Germantown Building;...
Making Advanced Computer Science Topics More Accessible through Interactive Technologies
ERIC Educational Resources Information Center
Shao, Kun; Maher, Peter
2012-01-01
Purpose: Teaching advanced technical concepts in a computer science program to students of different technical backgrounds presents many challenges. The purpose of this paper is to present a detailed experimental pedagogy in teaching advanced computer science topics, such as computer networking, telecommunications and data structures using…
77 FR 12823 - Advanced Scientific Computing Advisory Committee
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2012-03-02
... final report, Advanced Networking update Status from Computer Science COV Early Career technical talks Summary of Applied Math and Computer Science Workshops ASCR's new SBIR awards Data-intensive Science... Advanced Scientific Computing Advisory Committee AGENCY: Department of Energy, Office of Science....
Microgravity fluid management requirements of advanced solar dynamic power systems
NASA Technical Reports Server (NTRS)
Migra, Robert P.
1987-01-01
The advanced solar dynamic system (ASDS) program is aimed at developing the technology for highly efficient, lightweight space power systems. The approach is to evaluate Stirling, Brayton and liquid metal Rankine power conversion systems (PCS) over the temperature range of 1025 to 1400K, identify the critical technologies and develop these technologies. Microgravity fluid management technology is required in several areas of this program, namely, thermal energy storage (TES), heat pipe applications and liquid metal, two phase flow Rankine systems. Utilization of the heat of fusion of phase change materials offers potential for smaller, lighter TES systems. The candidate TES materials exhibit large volume change with the phase change. The heat pipe is an energy dense heat transfer device. A high temperature application may transfer heat from the solar receiver to the PCS working fluid and/or TES. A low temperature application may transfer waste heat from the PCS to the radiator. The liquid metal Rankine PCS requires management of the boiling/condensing process typical of two phase flow systems.
Computational Fluid Dynamics at NASA Ames Research Center
NASA Technical Reports Server (NTRS)
Kutler, Paul
1994-01-01
Computational fluid dynamics (CFD) is beginning to play a major role in the aircraft industry of the United States because of the realization that CFD can be a new and effective design tool and thus could provide a company with a competitive advantage. It is also playing a significant role in research institutions, both governmental and academic, as a tool for researching new fluid physics, as well as supplementing and complementing experimental testing. In this presentation, some of the progress made to date in CFD at NASA Ames will be reviewed. The presentation addresses the status of CFD in terms of methods, examples of CFD solutions, and computer technology. In addition, the role CFD will play in supporting the revolutionary goals set forth by the Aeronautical Policy Review Committee established by the Office of Science and Technology Policy is noted. The need for validated CFD tools is also briefly discussed.
Data Point Averaging for Computational Fluid Dynamics Data
NASA Technical Reports Server (NTRS)
Norman, Jr., David (Inventor)
2016-01-01
A system and method for generating fluid flow parameter data for use in aerodynamic heating analysis. Computational fluid dynamics data is generated for a number of points in an area on a surface to be analyzed. Sub-areas corresponding to areas of the surface for which an aerodynamic heating analysis is to be performed are identified. A computer system automatically determines a sub-set of the number of points corresponding to each of the number of sub-areas and determines a value for each of the number of sub-areas using the data for the sub-set of points corresponding to each of the number of sub-areas. The value is determined as an average of the data for the sub-set of points corresponding to each of the number of sub-areas. The resulting parameter values then may be used to perform an aerodynamic heating analysis.
Data Point Averaging for Computational Fluid Dynamics Data
NASA Technical Reports Server (NTRS)
Norman, David, Jr. (Inventor)
2014-01-01
A system and method for generating fluid flow parameter data for use in aerodynamic heating analysis. Computational fluid dynamics data is generated for a number of points in an area on a surface to be analyzed. Sub-areas corresponding to areas of the surface for which an aerodynamic heating analysis is to be performed are identified. A computer system automatically determines a sub-set of the number of points corresponding to each of the number of sub-areas and determines a value for each of the number of sub-areas using the data for the sub-set of points corresponding to each of the number of sub-areas. The value is determined as an average of the data for the sub-set of points corresponding to each of the number of sub-areas. The resulting parameter values then may be used to perform an aerodynamic heating analysis.
NASA Trapezoidal Wing Computations Including Transition and Advanced Turbulence Modeling
NASA Technical Reports Server (NTRS)
Rumsey, C. L.; Lee-Rausch, E. M.
2012-01-01
Flow about the NASA Trapezoidal Wing is computed with several turbulence models by using grids from the first High Lift Prediction Workshop in an effort to advance understanding of computational fluid dynamics modeling for this type of flowfield. Transition is accounted for in many of the computations. In particular, a recently-developed 4-equation transition model is utilized and works well overall. Accounting for transition tends to increase lift and decrease moment, which improves the agreement with experiment. Upper surface flap separation is reduced, and agreement with experimental surface pressures and velocity profiles is improved. The predicted shape of wakes from upstream elements is strongly influenced by grid resolution in regions above the main and flap elements. Turbulence model enhancements to account for rotation and curvature have the general effect of increasing lift and improving the resolution of the wing tip vortex as it convects downstream. However, none of the models improve the prediction of surface pressures near the wing tip, where more grid resolution is needed.
Computational Fluid Dynamics Analysis of Thoracic Aortic Dissection
NASA Astrophysics Data System (ADS)
Tang, Yik; Fan, Yi; Cheng, Stephen; Chow, Kwok
2011-11-01
Thoracic Aortic Dissection (TAD) is a cardiovascular disease with high mortality. An aortic dissection is formed when blood infiltrates the layers of the vascular wall, and a new artificial channel, the false lumen, is created. The expansion of the blood vessel due to the weakened wall enhances the risk of rupture. Computational fluid dynamics analysis is performed to study the hemodynamics of this pathological condition. Both idealized geometry and realistic patient configurations from computed tomography (CT) images are investigated. Physiological boundary conditions from in vivo measurements are employed. Flow configuration and biomechanical forces are studied. Quantitative analysis allows clinicians to assess the risk of rupture in making decision regarding surgical intervention.
Computational fluid dynamic analysis of hybrid rocket combustor flowfields
NASA Technical Reports Server (NTRS)
Venkateswaran, S.; Merkle, C. L.
1995-01-01
Computational fluid dynamic analyses of the Navier-Stokes equations coupled with solid-phase pyrolysis, gas-phase combustion, turbulence and radiation are performed to study hybrid rocket combustor flowfields. The computational study is closely co-ordinated with a companion experimental program using a planar slab burner configuration with HTPB as fuel and gaseous oxygen. Computational predictions agree reasonably well with measurement data of fuel regression rates and surface temperatures. Additionally, most of the parametric trends predicted by the model are in general agreement with experimental trends. The computational model is applied to extend the results from the lab-scale to a full-scale axisymmetric configuration. The numerical predictions indicate that the full-scale configuration burns at a slower rate than the lab-scale combustor under identical specific flow rate conditions. The results demonstrate that detailed CFD analyses can play a useful role in the design of hybrid combustors.
Parallel Computational Fluid Dynamics: Current Status and Future Requirements
NASA Technical Reports Server (NTRS)
Simon, Horst D.; VanDalsem, William R.; Dagum, Leonardo; Kutler, Paul (Technical Monitor)
1994-01-01
One or the key objectives of the Applied Research Branch in the Numerical Aerodynamic Simulation (NAS) Systems Division at NASA Allies Research Center is the accelerated introduction of highly parallel machines into a full operational environment. In this report we discuss the performance results obtained from the implementation of some computational fluid dynamics (CFD) applications on the Connection Machine CM-2 and the Intel iPSC/860. We summarize some of the experiences made so far with the parallel testbed machines at the NAS Applied Research Branch. Then we discuss the long term computational requirements for accomplishing some of the grand challenge problems in computational aerosciences. We argue that only massively parallel machines will be able to meet these grand challenge requirements, and we outline the computer science and algorithm research challenges ahead.
Application of advanced electronics to a future spacecraft computer design
NASA Technical Reports Server (NTRS)
Carney, P. C.
1980-01-01
Advancements in hardware and software technology are summarized with specific emphasis on spacecraft computer capabilities. Available state of the art technology is reviewed and candidate architectures are defined.
Recent Advances in Computational Mechanics of the Human Knee Joint
Kazemi, M.; Dabiri, Y.; Li, L. P.
2013-01-01
Computational mechanics has been advanced in every area of orthopedic biomechanics. The objective of this paper is to provide a general review of the computational models used in the analysis of the mechanical function of the knee joint in different loading and pathological conditions. Major review articles published in related areas are summarized first. The constitutive models for soft tissues of the knee are briefly discussed to facilitate understanding the joint modeling. A detailed review of the tibiofemoral joint models is presented thereafter. The geometry reconstruction procedures as well as some critical issues in finite element modeling are also discussed. Computational modeling can be a reliable and effective method for the study of mechanical behavior of the knee joint, if the model is constructed correctly. Single-phase material models have been used to predict the instantaneous load response for the healthy knees and repaired joints, such as total and partial meniscectomies, ACL and PCL reconstructions, and joint replacements. Recently, poromechanical models accounting for fluid pressurization in soft tissues have been proposed to study the viscoelastic response of the healthy and impaired knee joints. While the constitutive modeling has been considerably advanced at the tissue level, many challenges still exist in applying a good material model to three-dimensional joint simulations. A complete model validation at the joint level seems impossible presently, because only simple data can be obtained experimentally. Therefore, model validation may be concentrated on the constitutive laws using multiple mechanical tests of the tissues. Extensive model verifications at the joint level are still crucial for the accuracy of the modeling. PMID:23509602
Advanced ERS design using computer simulation
Melhem, G.A.
1995-12-31
There are two schools of thought regarding pressure relief design, shortcut/simplified methods and detailed methods. The shortcut/simplified methods are mostly applicable to non-reactive systems. These methods use direct scale-up techniques to obtain a vent size. Little useful information can be obtained for reaction data such as onset temperatures, activation energy, decompositon stoichiometry, etc. In addition, this approach does not readily provide the ability to perform what-if and sensitivity analysis or data that can be used for post-release mitigation design. The detailed approach advocates a more fundamental approach to pressure relief design, especially for reactive systems. First, the reaction chemistry is qualified using small scale experiments and then this data is coupled with fluid dynamics to design the emergency relief system. In addition to vent sizing information, this approach provides insights into process modification and refinement as well as the establishment of a safe operating envelope. This approach provides necessary flow data for vent containment design (if required), structural support, etc. This approach also allows the direct evaluation of design sensitivity to variables such as temperature, pressure, composition, fill level, etc. on vent sizing while the shortcut approach requires an additional experiment per what-if scenario. This approach meets DIERS technology requirements for two-phase flow and vapor/liquid disengagement and exceeds it in many key areas for reacting systems such as stoichiometry estimation for decomposition reactions, non-ideal solutions effects, continuing reactions in piping and vent containment systems, etc. This paper provides an overview of our proposed equation of state based modeling approach and its computer code implementation. Numerous examples and model validations are also described. 42 refs., 23 figs., 9 tabs.
77 FR 45345 - DOE/Advanced Scientific Computing Advisory Committee
Federal Register 2010, 2011, 2012, 2013, 2014
2012-07-31
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Developing an Advanced Environment for Collaborative Computing
NASA Technical Reports Server (NTRS)
Becerra-Fernandez, Irma; Stewart, Helen; DelAlto, Martha; DelAlto, Martha; Knight, Chris
1999-01-01
Knowledge management in general tries to organize and make available important know-how, whenever and where ever is needed. Today, organizations rely on decision-makers to produce "mission critical" decisions that am based on inputs from multiple domains. The ideal decision-maker has a profound understanding of specific domains that influence the decision-making process coupled with the experience that allows them to act quickly and decisively on the information. In addition, learning companies benefit by not repeating costly mistakes, and by reducing time-to-market in Research & Development projects. Group-decision making tools can help companies make better decisions by capturing the knowledge from groups of experts. Furthermore, companies that capture their customers preferences can improve their customer service, which translates to larger profits. Therefore collaborative computing provides a common communication space, improves sharing of knowledge, provides a mechanism for real-time feedback on the tasks being performed, helps to optimize processes, and results in a centralized knowledge warehouse. This paper presents the research directions. of a project which seeks to augment an advanced collaborative web-based environment called Postdoc, with workflow capabilities. Postdoc is a "government-off-the-shelf" document management software developed at NASA-Ames Research Center (ARC).
Computational Fluid Dynamic simulations of pipe elbow flow.
Homicz, Gregory Francis
2004-08-01
One problem facing today's nuclear power industry is flow-accelerated corrosion and erosion in pipe elbows. The Korean Atomic Energy Research Institute (KAERI) is performing experiments in their Flow-Accelerated Corrosion (FAC) test loop to better characterize these phenomena, and develop advanced sensor technologies for the condition monitoring of critical elbows on a continuous basis. In parallel with these experiments, Sandia National Laboratories is performing Computational Fluid Dynamic (CFD) simulations of the flow in one elbow of the FAC test loop. The simulations are being performed using the FLUENT commercial software developed and marketed by Fluent, Inc. The model geometry and mesh were created using the GAMBIT software, also from Fluent, Inc. This report documents the results of the simulations that have been made to date; baseline results employing the RNG k-e turbulence model are presented. The predicted value for the diametrical pressure coefficient is in reasonably good agreement with published correlations. Plots of the velocities, pressure field, wall shear stress, and turbulent kinetic energy adjacent to the wall are shown within the elbow section. Somewhat to our surprise, these indicate that the maximum values of both wall shear stress and turbulent kinetic energy occur near the elbow entrance, on the inner radius of the bend. Additional simulations were performed for the same conditions, but with the RNG k-e model replaced by either the standard k-{var_epsilon}, or the realizable k-{var_epsilon} turbulence model. The predictions using the standard k-{var_epsilon} model are quite similar to those obtained in the baseline simulation. However, with the realizable k-{var_epsilon} model, more significant differences are evident. The maximums in both wall shear stress and turbulent kinetic energy now appear on the outer radius, near the elbow exit, and are {approx}11% and 14% greater, respectively, than those predicted in the baseline calculation
State-of-the-art review of computational fluid dynamics modeling for fluid-solids systems
NASA Astrophysics Data System (ADS)
Lyczkowski, R. W.; Bouillard, J. X.; Ding, J.; Chang, S. L.; Burge, S. W.
1994-05-01
As the result of 15 years of research (50 staff years of effort) Argonne National Laboratory (ANL), through its involvement in fluidized-bed combustion, magnetohydrodynamics, and a variety of environmental programs, has produced extensive computational fluid dynamics (CFD) software and models to predict the multiphase hydrodynamic and reactive behavior of fluid-solids motions and interactions in complex fluidized-bed reactors (FBR's) and slurry systems. This has resulted in the FLUFIX, IRF, and SLUFIX computer programs. These programs are based on fluid-solids hydrodynamic models and can predict information important to the designer of atmospheric or pressurized bubbling and circulating FBR, fluid catalytic cracking (FCC) and slurry units to guarantee optimum efficiency with minimum release of pollutants into the environment. This latter issue will become of paramount importance with the enactment of the Clean Air Act Amendment (CAAA) of 1995. Solids motion is also the key to understanding erosion processes. Erosion rates in FBR's and pneumatic and slurry components are computed by ANL's EROSION code to predict the potential metal wastage of FBR walls, intervals, feed distributors, and cyclones. Only the FLUFIX and IRF codes will be reviewed in the paper together with highlights of the validations because of length limitations. It is envisioned that one day, these codes with user-friendly pre- and post-processor software and tailored for massively parallel multiprocessor shared memory computational platforms will be used by industry and researchers to assist in reducing and/or eliminating the environmental and economic barriers which limit full consideration of coal, shale, and biomass as energy sources; to retain energy security; and to remediate waste and ecological problems.
Applying uncertainty quantification to multiphase flow computational fluid dynamics
Gel, A; Garg, R; Tong, C; Shahnam, M; Guenther, C
2013-07-01
Multiphase computational fluid dynamics plays a major role in design and optimization of fossil fuel based reactors. There is a growing interest in accounting for the influence of uncertainties associated with physical systems to increase the reliability of computational simulation based engineering analysis. The U.S. Department of Energy's National Energy Technology Laboratory (NETL) has recently undertaken an initiative to characterize uncertainties associated with computer simulation of reacting multiphase flows encountered in energy producing systems such as a coal gasifier. The current work presents the preliminary results in applying non-intrusive parametric uncertainty quantification and propagation techniques with NETL's open-source multiphase computational fluid dynamics software MFIX. For this purpose an open-source uncertainty quantification toolkit, PSUADE developed at the Lawrence Livermore National Laboratory (LLNL) has been interfaced with MFIX software. In this study, the sources of uncertainty associated with numerical approximation and model form have been neglected, and only the model input parametric uncertainty with forward propagation has been investigated by constructing a surrogate model based on data-fitted response surface for a multiphase flow demonstration problem. Monte Carlo simulation was employed for forward propagation of the aleatory type input uncertainties. Several insights gained based on the outcome of these simulations are presented such as how inadequate characterization of uncertainties can affect the reliability of the prediction results. Also a global sensitivity study using Sobol' indices was performed to better understand the contribution of input parameters to the variability observed in response variable.
Alternative algorithms for computational fluid dynamics. Final report
Ladd, A.J.C.
1995-03-03
Fluid flow is conventionally modeled by finite difference or finite element approximations to the Navier-Stokes equations. The key problem in such calculations is devising an efficient computational mesh on which to solve the equations; if the geometry is complex, extensive human intervention is usually necessary. Thus these methods are unsuitable for problems such as the motion of solid particulates in suspension, where there may be many thousands of objects whose positions are constantly varying over the course of the simulation. Over the past few years I have developed an alternative strategy for modeling solid-fluid flows, based on a discrete Boltzmann model, in which the particle velocities are sampled from a small well-chosen set, commensurate with the underlying spatial lattice. This leads to a simple and fast numerical algorithm which can solve fluid flow problems with high accuracy on relatively crude spatial meshes. Thus it has been possible to track the motion of around 1000 hydrodynamically interacting particles on a desktop workstation. A preliminary account of some of this work was published in Physical Review Letters; a complete account of the method is given in two papers published by the Journal of Fluid Mechanics.
Computational fluid dynamics: A two-edged sword
Baker, A.J.; Kelso, R.M.; Gordon, E.B.; Roy, S.; Schaub, E.G.
1997-08-01
This article examines computational fluid dynamics (CFD) limitations as a design tool. Two decades have passed since the first paper was published in the ASHRAE Transactions suggesting the use of CFD for quantitative prediction of room air motion. CFD is an emerging methodology, with roots in the defense/aerospace industry, wherein a mathematical model of fluid flow is converted into a digital computational procedure, yielding numbers that approximate the solution of this modeled system, hence the genuine flow state. CFD methodology has indeed brought bright glimmers of an ability to establish firm quantitative data regarding how room air moves. In fact, CFD can predict fluid levels and pressure differences to very low levels, that are essentially impossible to experimentally measure. However, a CFD model constitutes the culmination of a large number of assumptions and approximations, such that the answers produced are essentially never correct. Further, it is the very approximation process in CFD theory that leads to intrinsic error mechanisms that can range from benign to pathological. The ASHRAE professional who seeks to use CFD to assist in system design needs to be fully aware of these two edges of the CFD sword.
Issues in computational fluid dynamics code verification and validation
Oberkampf, W.L.; Blottner, F.G.
1997-09-01
A broad range of mathematical modeling errors of fluid flow physics and numerical approximation errors are addressed in computational fluid dynamics (CFD). It is strongly believed that if CFD is to have a major impact on the design of engineering hardware and flight systems, the level of confidence in complex simulations must substantially improve. To better understand the present limitations of CFD simulations, a wide variety of physical modeling, discretization, and solution errors are identified and discussed. Here, discretization and solution errors refer to all errors caused by conversion of the original partial differential, or integral, conservation equations representing the physical process, to algebraic equations and their solution on a computer. The impact of boundary conditions on the solution of the partial differential equations and their discrete representation will also be discussed. Throughout the article, clear distinctions are made between the analytical mathematical models of fluid dynamics and the numerical models. Lax`s Equivalence Theorem and its frailties in practical CFD solutions are pointed out. Distinctions are also made between the existence and uniqueness of solutions to the partial differential equations as opposed to the discrete equations. Two techniques are briefly discussed for the detection and quantification of certain types of discretization and grid resolution errors.
Advanced computational research in materials processing for design and manufacturing
Zacharia, T.
1995-04-01
Advanced mathematical techniques and computer simulation play a major role in providing enhanced understanding of conventional and advanced materials processing operations. Development and application of mathematical models and computer simulation techniques can provide a quantitative understanding of materials processes and will minimize the need for expensive and time consuming trial- and error-based product development. As computer simulations and materials databases grow in complexity, high performance computing and simulation are expected to play a key role in supporting the improvements required in advanced material syntheses and processing by lessening the dependence on expensive prototyping and re-tooling. Many of these numerical models are highly compute-intensive. It is not unusual for an analysis to require several hours of computational time on current supercomputers despite the simplicity of the models being studied. For example, to accurately simulate the heat transfer in a 1-m{sup 3} block using a simple computational method requires 10`2 arithmetic operations per second of simulated time. For a computer to do the simulation in real time would require a sustained computation rate 1000 times faster than that achievable by current supercomputers. Massively parallel computer systems, which combine several thousand processors able to operate concurrently on a problem are expected to provide orders of magnitude increase in performance. This paper briefly describes advanced computational research in materials processing at ORNL. Continued development of computational techniques and algorithms utilizing the massively parallel computers will allow the simulation of conventional and advanced materials processes in sufficient generality.
Advanced flight computers for planetary exploration
NASA Astrophysics Data System (ADS)
Stephenson, R. Rhoads
Research concerning flight computers for use on interplanetary probes is reviewed. The history of these computers from the Viking mission to the present is outlined. The differences between ground commercial computers and computers for planetary exploration are listed. The development of a computer for the Mariner Mark II comet rendezvous asteroid flyby mission is described. Various aspects of recently developed computer systems are examined, including the Max real time, embedded computer, a hypercube distributed supercomputer, a SAR data processor, a processor for the High Resolution IR Imaging Spectrometer, and a robotic vision multiresolution pyramid machine for processsing images obtained by a Mars Rover.
Advanced flight computers for planetary exploration
NASA Technical Reports Server (NTRS)
Stephenson, R. Rhoads
1988-01-01
Research concerning flight computers for use on interplanetary probes is reviewed. The history of these computers from the Viking mission to the present is outlined. The differences between ground commercial computers and computers for planetary exploration are listed. The development of a computer for the Mariner Mark II comet rendezvous asteroid flyby mission is described. Various aspects of recently developed computer systems are examined, including the Max real time, embedded computer, a hypercube distributed supercomputer, a SAR data processor, a processor for the High Resolution IR Imaging Spectrometer, and a robotic vision multiresolution pyramid machine for processsing images obtained by a Mars Rover.
Computational Fluid Dynamics of Whole-Body Aircraft
NASA Astrophysics Data System (ADS)
Agarwal, Ramesh
1999-01-01
The current state of the art in computational aerodynamics for whole-body aircraft flowfield simulations is described. Recent advances in geometry modeling, surface and volume grid generation, and flow simulation algorithms have led to accurate flowfield predictions for increasingly complex and realistic configurations. As a result, computational aerodynamics has emerged as a crucial enabling technology for the design and development of flight vehicles. Examples illustrating the current capability for the prediction of transport and fighter aircraft flowfields are presented. Unfortunately, accurate modeling of turbulence remains a major difficulty in the analysis of viscosity-dominated flows. In the future, inverse design methods, multidisciplinary design optimization methods, artificial intelligence technology, and massively parallel computer technology will be incorporated into computational aerodynamics, opening up greater opportunities for improved product design at substantially reduced costs.
FAST - A multiprocessed environment for visualization of computational fluid dynamics
NASA Technical Reports Server (NTRS)
Bancroft, Gordon V.; Merritt, Fergus J.; Plessel, Todd C.; Kelaita, Paul G.; Mccabe, R. Kevin
1991-01-01
The paper presents the Flow Analysis Software Toolset (FAST) to be used for fluid-mechanics analysis. The design criteria for FAST including the minimization of the data path in the computational fluid-dynamics (CFD) process, consistent user interface, extensible software architecture, modularization, and the isolation of three-dimensional tasks from the application programmer are outlined. Each separate process communicates through the FAST Hub, while other modules such as FAST Central, NAS file input, CFD calculator, surface extractor and renderer, titler, tracer, and isolev might work together to generate the scene. An interprocess communication package making it possible for FAST to operate as a modular environment where resources could be shared among different machines as well as a single host is discussed.
76 FR 64330 - Advanced Scientific Computing Advisory Committee
Federal Register 2010, 2011, 2012, 2013, 2014
2011-10-18
... Workshop on Mathematics for the Analysis, Simulation, and Optimization of Complex Systems Report from ASCR..., Office of Advanced Scientific Computing Research; SC-21/Germantown Building; U. S. Department of Energy... Department of Energy on scientific priorities within the field of advanced scientific computing...
NASA Astrophysics Data System (ADS)
Korobenko, Artem
During the last several decades engineers and scientists put significant effort into developing reliable and efficient wind turbines. As a wind power production demands grow, the wind energy research and development need to be enhanced with high-precision methods and tools. These include time-dependent, full-scale, complex-geometry advanced computational simulations at large-scale. Those, computational analysis of wind turbines, including fluid-structure interaction simulations (FSI) at full scale is important for accurate and reliable modeling, as well as blade failure prediction and design optimization. In current dissertation the FSI framework is applied to most challenging class of problems, such as large scale horizontal axis wind turbines and vertical axis wind turbines. The governing equations for aerodynamics and structural mechanics together with coupled formulation are explained in details. The simulations are performed for different wind turbine designs, operational conditions and validated against field-test and wind tunnel experimental data.
Computational fluid dynamics studies of nuclear rocket performance
NASA Technical Reports Server (NTRS)
Stubbs, Robert M.; Kim, Suk C.; Benson, Thomas J.
1994-01-01
A CFD analysis of a low pressure nuclear rocket concept is presented with the use of an advanced chemical kinetics, Navier-Stokes code. The computations describe the flow field in detail, including gas dynamic, thermodynamic and chemical properties, as well as global performance quantities such as specific impulse. Computational studies of several rocket nozzle shapes are conducted in an attempt to maximize hydrogen recombination. These Navier-Stokes calculations, which include real gas and viscous effects, predict lower performance values than have been reported heretofore.
Computational fluid dynamics studies of nuclear rocket performance
NASA Technical Reports Server (NTRS)
Stubbs, Robert M.; Benson, Thomas J.; Kim, Suk C.
1991-01-01
A CFD analysis of a low pressure nuclear rocket concept is presented with the use of an advanced chemical kinetics, Navier-Stokes code. The computations describe the flow field in detail,including gas dynamic, thermodynamic and chemical properties, as well as global performance quantities such as specific impulse. Computational studies of several rocket nozzle shapes are conducted in an attempt to maximize hydrogen recombination. These Navier-Stokes calculations, which include real gas and viscous effects, predict lower performance values than have been reported heretofore.
High-Performance Java Codes for Computational Fluid Dynamics
NASA Technical Reports Server (NTRS)
Riley, Christopher; Chatterjee, Siddhartha; Biswas, Rupak; Biegel, Bryan (Technical Monitor)
2001-01-01
The computational science community is reluctant to write large-scale computationally -intensive applications in Java due to concerns over Java's poor performance, despite the claimed software engineering advantages of its object-oriented features. Naive Java implementations of numerical algorithms can perform poorly compared to corresponding Fortran or C implementations. To achieve high performance, Java applications must be designed with good performance as a primary goal. This paper presents the object-oriented design and implementation of two real-world applications from the field of Computational Fluid Dynamics (CFD): a finite-volume fluid flow solver (LAURA, from NASA Langley Research Center), and an unstructured mesh adaptation algorithm (2D_TAG, from NASA Ames Research Center). This work builds on our previous experience with the design of high-performance numerical libraries in Java. We examine the performance of the applications using the currently available Java infrastructure and show that the Java version of the flow solver LAURA performs almost within a factor of 2 of the original procedural version. Our Java version of the mesh adaptation algorithm 2D_TAG performs within a factor of 1.5 of its original procedural version on certain platforms. Our results demonstrate that object-oriented software design principles are not necessarily inimical to high performance.
Aircraft T-tail flutter predictions using computational fluid dynamics
NASA Astrophysics Data System (ADS)
Attorni, A.; Cavagna, L.; Quaranta, G.
2011-02-01
The paper presents the application of computational aeroelasticity (CA) methods to the analysis of a T-tail stability in transonic regime. For this flow condition unsteady aerodynamics show a significant dependency from the aircraft equilibrium flight configuration, which rules both the position of shock waves in the flow field and the load distribution on the horizontal tail plane. Both these elements have an influence on the aerodynamic forces, and so on the aeroelastic stability of the system. The numerical procedure proposed allows to investigate flutter stability for a free-flying aircraft, iterating until convergence the following sequence of sub-problems: search for the trimmed condition for the deformable aircraft; linearize the system about the stated equilibrium point; predict the aeroelastic stability boundaries using the inferred linear model. An innovative approach based on sliding meshes allows to represent the changes of the computational fluid domain due to the motion of control surfaces used to trim the aircraft. To highlight the importance of keeping the linear model always aligned to the trim condition, and at the same time the capabilities of the computational fluid dynamics approach, the method is applied to a real aircraft with a T-tail configuration: the P180.
Executive Summary: Special Section on Credible Computational Fluid Dynamics Simulations
NASA Technical Reports Server (NTRS)
Mehta, Unmeel B.
1998-01-01
This summary presents the motivation for the Special Section on the credibility of computational fluid dynamics (CFD) simulations, its objective, its background and context, its content, and its major conclusions. Verification and validation (V&V) are the processes for establishing the credibility of CFD simulations. Validation assesses whether correct things are performed and verification assesses whether they are performed correctly. Various aspects of V&V are discussed. Progress is made in verification of simulation models. Considerable effort is still needed for developing a systematic validation method that can assess the credibility of simulated reality.
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.
New Challenges in Visualization of Computational Fluid Dynamics
NASA Technical Reports Server (NTRS)
Gerald-Yamasaki, Michael; Chancellor, Marisa K. (Technical Monitor)
1997-01-01
The development of visualization systems for analyzing computational fluid dynamics data has been driven by increasing size and complexity of the data. New extensions to the system domain into analysis of data from multiple sources, parameter space studies, and multidisciplinary studies in support of integrated aeronautical design systems provide new g challenges for the visualization system developer. Recent work at NASA Ames Research Center in visualization systems, automatic flow feature detection, unsteady flow visualization techniques, and a new area, data exploitation, will be discussed in the context of NASA information technology initiatives.
NASA Technical Reports Server (NTRS)
Thorp, Scott A.
1992-01-01
This presentation will discuss the development of a NASA Geometry Exchange Specification for transferring aerodynamic surface geometry between LeRC systems and grid generation software used for computational fluid dynamics research. The proposed specification is based on a subset of the Initial Graphics Exchange Specification (IGES). The presentation will include discussion of how the NASA-IGES standard will accommodate improved computer aided design inspection methods and reverse engineering techniques currently being developed. The presentation is in viewgraph format.
Some Recent Advances in Computer Graphics.
ERIC Educational Resources Information Center
Whitted, Turner
1982-01-01
General principles of computer graphics are reviewed, including discussions of display hardware, geometric modeling, algorithms, and applications in science, computer-aided design, flight training, communications, business, art, and entertainment. (JN)
Computational Fluid Dynamics Demonstration of Rigid Bodies in Motion
NASA Technical Reports Server (NTRS)
Camarena, Ernesto; Vu, Bruce T.
2011-01-01
The Design Analysis Branch (NE-Ml) at the Kennedy Space Center has not had the ability to accurately couple Rigid Body Dynamics (RBD) and Computational Fluid Dynamics (CFD). OVERFLOW-D is a flow solver that has been developed by NASA to have the capability to analyze and simulate dynamic motions with up to six Degrees of Freedom (6-DOF). Two simulations were prepared over the course of the internship to demonstrate 6DOF motion of rigid bodies under aerodynamic loading. The geometries in the simulations were based on a conceptual Space Launch System (SLS). The first simulation that was prepared and computed was the motion of a Solid Rocket Booster (SRB) as it separates from its core stage. To reduce computational time during the development of the simulation, only half of the physical domain with respect to the symmetry plane was simulated. Then a full solution was prepared and computed. The second simulation was a model of the SLS as it departs from a launch pad under a 20 knot crosswind. This simulation was reduced to Two Dimensions (2D) to reduce both preparation and computation time. By allowing 2-DOF for translations and 1-DOF for rotation, the simulation predicted unrealistic rotation. The simulation was then constrained to only allow translations.
Computing Advances in the Teaching of Chemistry.
ERIC Educational Resources Information Center
Baskett, W. P.; Matthews, G. P.
1984-01-01
Discusses three trends in computer-oriented chemistry instruction: (1) availability of interfaces to integrate computers with experiments; (2) impact of the development of higher resolution graphics and greater memory capacity; and (3) role of videodisc technology on computer assisted instruction. Includes program listings for auto-titration and…
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.
Computational toxicology (CompTox) leverages the significant gains in computing power and computational techniques (e.g., numerical approaches, structure-activity relationships, bioinformatics) realized over the last few years, thereby reducing costs and increasing efficiency i...
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.
Immersive visualization for enhanced computational fluid dynamics analysis.
Quam, David J; Gundert, Timothy J; Ellwein, Laura; Larkee, Christopher E; Hayden, Paul; Migrino, Raymond Q; Otake, Hiromasa; LaDisa, John F
2015-03-01
Modern biomedical computer simulations produce spatiotemporal results that are often viewed at a single point in time on standard 2D displays. An immersive visualization environment (IVE) with 3D stereoscopic capability can mitigate some shortcomings of 2D displays via improved depth cues and active movement to further appreciate the spatial localization of imaging data with temporal computational fluid dynamics (CFD) results. We present a semi-automatic workflow for the import, processing, rendering, and stereoscopic visualization of high resolution, patient-specific imaging data, and CFD results in an IVE. Versatility of the workflow is highlighted with current clinical sequelae known to be influenced by adverse hemodynamics to illustrate potential clinical utility. PMID:25378201
Parallelization of implicit finite difference schemes in computational fluid dynamics
NASA Technical Reports Server (NTRS)
Decker, Naomi H.; Naik, Vijay K.; Nicoules, Michel
1990-01-01
Implicit finite difference schemes are often the preferred numerical schemes in computational fluid dynamics, requiring less stringent stability bounds than the explicit schemes. Each iteration in an implicit scheme involves global data dependencies in the form of second and higher order recurrences. Efficient parallel implementations of such iterative methods are considerably more difficult and non-intuitive. The parallelization of the implicit schemes that are used for solving the Euler and the thin layer Navier-Stokes equations and that require inversions of large linear systems in the form of block tri-diagonal and/or block penta-diagonal matrices is discussed. Three-dimensional cases are emphasized and schemes that minimize the total execution time are presented. Partitioning and scheduling schemes for alleviating the effects of the global data dependencies are described. An analysis of the communication and the computation aspects of these methods is presented. The effect of the boundary conditions on the parallel schemes is also discussed.
Computational Fluid Dynamics Analysis of Canadian Supercritical Water Reactor (SCWR)
NASA Astrophysics Data System (ADS)
Movassat, Mohammad; Bailey, Joanne; Yetisir, Metin
2015-11-01
A Computational Fluid Dynamics (CFD) simulation was performed on the proposed design for the Canadian SuperCritical Water Reactor (SCWR). The proposed Canadian SCWR is a 1200 MW(e) supercritical light-water cooled nuclear reactor with pressurized fuel channels. The reactor concept uses an inlet plenum that all fuel channels are attached to and an outlet header nested inside the inlet plenum. The coolant enters the inlet plenum at 350 C and exits the outlet header at 625 C. The operating pressure is approximately 26 MPa. The high pressure and high temperature outlet conditions result in a higher electric conversion efficiency as compared to existing light water reactors. In this work, CFD simulations were performed to model fluid flow and heat transfer in the inlet plenum, outlet header, and various parts of the fuel assembly. The ANSYS Fluent solver was used for simulations. Results showed that mass flow rate distribution in fuel channels varies radially and the inner channels achieve higher outlet temperatures. At the outlet header, zones with rotational flow were formed as the fluid from 336 fuel channels merged. Results also suggested that insulation of the outlet header should be considered to reduce the thermal stresses caused by the large temperature gradients.
Adaptive kinetic-fluid solvers for heterogeneous computing architectures
NASA Astrophysics Data System (ADS)
Zabelok, Sergey; Arslanbekov, Robert; Kolobov, Vladimir
2015-12-01
We show feasibility and benefits of porting an adaptive multi-scale kinetic-fluid code to CPU-GPU systems. Challenges are due to the irregular data access for adaptive Cartesian mesh, vast difference of computational cost between kinetic and fluid cells, and desire to evenly load all CPUs and GPUs during grid adaptation and algorithm refinement. Our Unified Flow Solver (UFS) combines Adaptive Mesh Refinement (AMR) with automatic cell-by-cell selection of kinetic or fluid solvers based on continuum breakdown criteria. Using GPUs enables hybrid simulations of mixed rarefied-continuum flows with a million of Boltzmann cells each having a 24 × 24 × 24 velocity mesh. We describe the implementation of CUDA kernels for three modules in UFS: the direct Boltzmann solver using the discrete velocity method (DVM), the Direct Simulation Monte Carlo (DSMC) solver, and a mesoscopic solver based on the Lattice Boltzmann Method (LBM), all using adaptive Cartesian mesh. Double digit speedups on single GPU and good scaling for multi-GPUs have been demonstrated.
Computational thermal, chemical, fluid, and solid mechanics for geosystems management.
Davison, Scott; Alger, Nicholas; Turner, Daniel Zack; Subia, Samuel Ramirez; Carnes, Brian; Martinez, Mario J.; Notz, Patrick K.; Klise, Katherine A.; Stone, Charles Michael; Field, Richard V., Jr.; Newell, Pania; Jove-Colon, Carlos F.; Red-Horse, John Robert; Bishop, Joseph E.; Dewers, Thomas A.; Hopkins, Polly L.; Mesh, Mikhail; Bean, James E.; Moffat, Harry K.; Yoon, Hongkyu
2011-09-01
This document summarizes research performed under the SNL LDRD entitled - Computational Mechanics for Geosystems Management to Support the Energy and Natural Resources Mission. The main accomplishment was development of a foundational SNL capability for computational thermal, chemical, fluid, and solid mechanics analysis of geosystems. The code was developed within the SNL Sierra software system. This report summarizes the capabilities of the simulation code and the supporting research and development conducted under this LDRD. The main goal of this project was the development of a foundational capability for coupled thermal, hydrological, mechanical, chemical (THMC) simulation of heterogeneous geosystems utilizing massively parallel processing. To solve these complex issues, this project integrated research in numerical mathematics and algorithms for chemically reactive multiphase systems with computer science research in adaptive coupled solution control and framework architecture. This report summarizes and demonstrates the capabilities that were developed together with the supporting research underlying the models. Key accomplishments are: (1) General capability for modeling nonisothermal, multiphase, multicomponent flow in heterogeneous porous geologic materials; (2) General capability to model multiphase reactive transport of species in heterogeneous porous media; (3) Constitutive models for describing real, general geomaterials under multiphase conditions utilizing laboratory data; (4) General capability to couple nonisothermal reactive flow with geomechanics (THMC); (5) Phase behavior thermodynamics for the CO2-H2O-NaCl system. General implementation enables modeling of other fluid mixtures. Adaptive look-up tables enable thermodynamic capability to other simulators; (6) Capability for statistical modeling of heterogeneity in geologic materials; and (7) Simulator utilizes unstructured grids on parallel processing computers.
Improvement in computational fluid dynamics through boundary verification and preconditioning
NASA Astrophysics Data System (ADS)
Folkner, David E.
This thesis provides improvements to computational fluid dynamics accuracy and efficiency through two main methods: a new boundary condition verification procedure and preconditioning techniques. First, a new verification approach that addresses boundary conditions was developed. In order to apply the verification approach to a large range of arbitrary boundary conditions, it was necessary to develop unifying mathematical formulation. A framework was developed that allows for the application of Dirichlet, Neumann, and extrapolation boundary condition, or in some cases the equations of motion directly. Verification of boundary condition techniques was performed using exact solutions from canonical fluid dynamic test cases. Second, to reduce computation time and improve accuracy, preconditioning algorithms were applied via artificial dissipation schemes. A new convective upwind and split pressure (CUSP) scheme was devised and was shown to be more effective than traditional preconditioning schemes in certain scenarios. The new scheme was compared with traditional schemes for unsteady flows for which both convective and acoustic effects dominated. Both boundary conditions and preconditioning algorithms were implemented in the context of a "strand grid" solver. While not the focus of this thesis, strand grids provide automatic viscous quality meshing and are suitable for moving mesh overset problems.
PArallel Reacting Multiphase FLOw Computational Fluid Dynamic Analysis
Energy Science and Technology Software Center (ESTSC)
2002-06-01
PARMFLO is a parallel multiphase reacting flow computational fluid dynamics (CFD) code. It can perform steady or unsteady simulations in three space dimensions. It is intended for use in engineering CFD analysis of industrial flow system components. Its parallel processing capabilities allow it to be applied to problems that use at least an order of magnitude more computational cells than the number that can be used on a typical single processor workstation (about 106 cellsmore » in parallel processing mode versus about io cells in serial processing mode). Alternately, by spreading the work of a CFD problem that could be run on a single workstation over a group of computers on a network, it can bring the runtime down by an order of magnitude or more (typically from many days to less than one day). The software was implemented using the industry standard Message-Passing Interface (MPI) and domain decomposition in one spatial direction. The phases of a flow problem may include an ideal gas mixture with an arbitrary number of chemical species, and dispersed droplet and particle phases. Regions of porous media may also be included within the domain. The porous media may be packed beds, foams, or monolith catalyst supports. With these features, the code is especially suited to analysis of mixing of reactants in the inlet chamber of catalytic reactors coupled to computation of product yields that result from the flow of the mixture through the catalyst coaled support structure.« less
PArallel Reacting Multiphase FLOw Computational Fluid Dynamic Analysis
Lottes, Steven A.
2002-06-01
PARMFLO is a parallel multiphase reacting flow computational fluid dynamics (CFD) code. It can perform steady or unsteady simulations in three space dimensions. It is intended for use in engineering CFD analysis of industrial flow system components. Its parallel processing capabilities allow it to be applied to problems that use at least an order of magnitude more computational cells than the number that can be used on a typical single processor workstation (about 106 cells in parallel processing mode versus about io cells in serial processing mode). Alternately, by spreading the work of a CFD problem that could be run on a single workstation over a group of computers on a network, it can bring the runtime down by an order of magnitude or more (typically from many days to less than one day). The software was implemented using the industry standard Message-Passing Interface (MPI) and domain decomposition in one spatial direction. The phases of a flow problem may include an ideal gas mixture with an arbitrary number of chemical species, and dispersed droplet and particle phases. Regions of porous media may also be included within the domain. The porous media may be packed beds, foams, or monolith catalyst supports. With these features, the code is especially suited to analysis of mixing of reactants in the inlet chamber of catalytic reactors coupled to computation of product yields that result from the flow of the mixture through the catalyst coaled support structure.
Advancing crime scene computer forensics techniques
NASA Astrophysics Data System (ADS)
Hosmer, Chet; Feldman, John; Giordano, Joe
1999-02-01
Computers and network technology have become inexpensive and powerful tools that can be applied to a wide range of criminal activity. Computers have changed the world's view of evidence because computers are used more and more as tools in committing `traditional crimes' such as embezzlements, thefts, extortion and murder. This paper will focus on reviewing the current state-of-the-art of the data recovery and evidence construction tools used in both the field and laboratory for prosection purposes.
ADVANCED COMPUTATIONAL METHODS IN DOSE MODELING
The overall goal of the EPA-ORD NERL research program on Computational Toxicology (CompTox) is to provide the Agency with the tools of modern chemistry, biology, and computing to improve quantitative risk assessments and reduce uncertainties in the source-to-adverse outcome conti...
Transonic wing analysis using advanced computational methods
NASA Technical Reports Server (NTRS)
Henne, P. A.; Hicks, R. M.
1978-01-01
This paper discusses the application of three-dimensional computational transonic flow methods to several different types of transport wing designs. The purpose of these applications is to evaluate the basic accuracy and limitations associated with such numerical methods. The use of such computational methods for practical engineering problems can only be justified after favorable evaluations are completed. The paper summarizes a study of both the small-disturbance and the full potential technique for computing three-dimensional transonic flows. Computed three-dimensional results are compared to both experimental measurements and theoretical results. Comparisons are made not only of pressure distributions but also of lift and drag forces. Transonic drag rise characteristics are compared. Three-dimensional pressure distributions and aerodynamic forces, computed from the full potential solution, compare reasonably well with experimental results for a wide range of configurations and flow conditions.
Wu, Binxin
2010-12-01
In this paper, 12 turbulence models for single-phase non-newtonian fluid flow in a pipe are evaluated by comparing the frictional pressure drops obtained from computational fluid dynamics (CFD) with those from three friction factor correlations. The turbulence models studied are (1) three high-Reynolds-number k-ε models, (2) six low-Reynolds-number k-ε models, (3) two k-ω models, and (4) the Reynolds stress model. The simulation results indicate that the Chang-Hsieh-Chen version of the low-Reynolds-number k-ε model performs better than the other models in predicting the frictional pressure drops while the standard k-ω model has an acceptable accuracy and a low computing cost. In the model applications, CFD simulation of mixing in a full-scale anaerobic digester with pumped circulation is performed to propose an improvement in the effective mixing standards recommended by the U.S. EPA based on the effect of rheology on the flow fields. Characterization of the velocity gradient is conducted to quantify the growth or breakage of an assumed floc size. Placement of two discharge nozzles in the digester is analyzed to show that spacing two nozzles 180° apart with each one discharging at an angle of 45° off the wall is the most efficient. Moreover, the similarity rules of geometry and mixing energy are checked for scaling up the digester. PMID:21047058
Efficient Parallel Kernel Solvers for Computational Fluid Dynamics Applications
NASA Technical Reports Server (NTRS)
Sun, Xian-He
1997-01-01
Distributed-memory parallel computers dominate today's parallel computing arena. These machines, such as Intel Paragon, IBM SP2, and Cray Origin2OO, have successfully delivered high performance computing power for solving some of the so-called "grand-challenge" problems. Despite initial success, parallel machines have not been widely accepted in production engineering environments due to the complexity of parallel programming. On a parallel computing system, a task has to be partitioned and distributed appropriately among processors to reduce communication cost and to attain load balance. More importantly, even with careful partitioning and mapping, the performance of an algorithm may still be unsatisfactory, since conventional sequential algorithms may be serial in nature and may not be implemented efficiently on parallel machines. In many cases, new algorithms have to be introduced to increase parallel performance. In order to achieve optimal performance, in addition to partitioning and mapping, a careful performance study should be conducted for a given application to find a good algorithm-machine combination. This process, however, is usually painful and elusive. The goal of this project is to design and develop efficient parallel algorithms for highly accurate Computational Fluid Dynamics (CFD) simulations and other engineering applications. The work plan is 1) developing highly accurate parallel numerical algorithms, 2) conduct preliminary testing to verify the effectiveness and potential of these algorithms, 3) incorporate newly developed algorithms into actual simulation packages. The work plan has well achieved. Two highly accurate, efficient Poisson solvers have been developed and tested based on two different approaches: (1) Adopting a mathematical geometry which has a better capacity to describe the fluid, (2) Using compact scheme to gain high order accuracy in numerical discretization. The previously developed Parallel Diagonal Dominant (PDD) algorithm
Computing Algorithms for Nuffield Advanced Physics.
ERIC Educational Resources Information Center
Summers, M. K.
1978-01-01
Defines all recurrence relations used in the Nuffield course, to solve first- and second-order differential equations, and describes a typical algorithm for computer generation of solutions. (Author/GA)
Aerodynamic optimization studies on advanced architecture computers
NASA Technical Reports Server (NTRS)
Chawla, Kalpana
1995-01-01
The approach to carrying out multi-discipline aerospace design studies in the future, especially in massively parallel computing environments, comprises of choosing (1) suitable solvers to compute solutions to equations characterizing a discipline, and (2) efficient optimization methods. In addition, for aerodynamic optimization problems, (3) smart methodologies must be selected to modify the surface shape. In this research effort, a 'direct' optimization method is implemented on the Cray C-90 to improve aerodynamic design. It is coupled with an existing implicit Navier-Stokes solver, OVERFLOW, to compute flow solutions. The optimization method is chosen such that it can accomodate multi-discipline optimization in future computations. In the work , however, only single discipline aerodynamic optimization will be included.
Computational Fluid Dynamics Framework for Turbine Biological Performance Assessment
Richmond, Marshall C.; Serkowski, John A.; Carlson, Thomas J.; Ebner, Laurie L.; Sick, Mirjam; Cada, G. F.
2011-05-04
In this paper, a method for turbine biological performance assessment is introduced to bridge the gap between field and laboratory studies on fish injury and turbine design. Using this method, a suite of biological performance indicators is computed based on simulated data from a computational fluid dynamics (CFD) model of a proposed turbine design. Each performance indicator is a measure of the probability of exposure to a certain dose of an injury mechanism. If the relationship between the dose of an injury mechanism and frequency of injury (dose-response) is known from laboratory or field studies, the likelihood of fish injury for a turbine design can be computed from the performance indicator. By comparing the values of the indicators from various turbine designs, the engineer can identify the more-promising designs. Discussion here is focused on Kaplan-type turbines, although the method could be extended to other designs. Following the description of the general methodology, we will present sample risk assessment calculations based on CFD data from a model of the John Day Dam on the Columbia River in the USA.
Fluid Dynamics of Competitive Swimming: A Computational Study
NASA Astrophysics Data System (ADS)
Mittal, Rajat; Loebbeck, Alfred; Singh, Hersh; Mark, Russell; Wei, Timothy
2004-11-01
The dolphin kick is an important component in competitive swimming and is used extensively by swimmers immediately following the starting dive as well as after turns. In this stroke, the swimmer swims about three feet under the water surface and the stroke is executed by performing an undulating wave-like motion of the body that is quite similar to the anguilliform propulsion mode in fish. Despite the relatively simple kinematics of this stoke, considerable variability in style and performance is observed even among Olympic level swimmers. Motivated by this, a joint experimental-numerical study has been initiated to examine the fluid-dynamics of this stroke. The current presentation will describe the computational portion of this study. The computations employ a sharp interface immersed boundary method (IBM) which allows us to simulate flows with complex moving boudnaries on stationary Cartesian grids. 3D body scans of male and female Olympic swimmers have been obtained and these are used in conjuction with high speed videos to recreate a realistic dolphin kick for the IBM solver. Preliminary results from these computations will be presented.
Advanced Crew Personal Support Computer (CPSC) task
NASA Technical Reports Server (NTRS)
Muratore, Debra
1991-01-01
The topics are presented in view graph form and include: background; objectives of task; benefits to the Space Station Freedom (SSF) Program; technical approach; baseline integration; and growth and evolution options. The objective is to: (1) introduce new computer technology into the SSF Program; (2) augment core computer capabilities to meet additional mission requirements; (3) minimize risk in upgrading technology; and (4) provide a low cost way to enhance crew and ground operations support.
Frontiers of research in advanced computations
1996-07-01
The principal mission of the Institute for Scientific Computing Research is to foster interactions among LLNL researchers, universities, and industry on selected topics in scientific computing. In the area of computational physics, the Institute has developed a new algorithm, GaPH, to help scientists understand the chemistry of turbulent and driven plasmas or gases at far less cost than other methods. New low-frequency electromagnetic models better describe the plasma etching and deposition characteristics of a computer chip in the making. A new method for modeling realistic curved boundaries within an orthogonal mesh is resulting in a better understanding of the physics associated with such boundaries and much quicker solutions. All these capabilities are being developed for massively parallel implementation, which is an ongoing focus of Institute researchers. Other groups within the Institute are developing novel computational methods to address a range of other problems. Examples include feature detection and motion recognition by computer, improved monitoring of blood oxygen levels, and entirely new models of human joint mechanics and prosthetic devices.