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Sample records for mechanics fluids engineering

  1. Fluid Mechanics

    NASA Astrophysics Data System (ADS)

    Pnueli, David; Gutfinger, Chaim

    1997-01-01

    This text is intended for the study of fluid mechanics at an intermediate level. The presentation starts with basic concepts, in order to form a sound conceptual structure that can support engineering applications and encourage further learning. The presentation is exact, incorporating both the mathematics involved and the physics needed to understand the various phenomena in fluid mechanics. Where a didactical choice must be made between the two, the physics prevails. Throughout the book the authors have tried to reach a balance between exact presentation, intuitive grasp of new ideas, and creative applications of concepts. This approach is reflected in the examples presented in the text and in the exercises given at the end of each chapter. Subjects treated are hydrostatics, viscous flow, similitude and order of magnitude, creeping flow, potential flow, boundary layer flow, turbulent flow, compressible flow, and non-Newtonian flows. This book is ideal for advanced undergraduate students in mechanical, chemical, aerospace, and civil engineering. Solutions manual available.

  2. Fluid Mechanics.

    ERIC Educational Resources Information Center

    Drazin, Philip

    1987-01-01

    Outlines the contents of Volume II of "Principia" by Sir Isaac Newton. Reviews the contributions of subsequent scientists to the physics of fluid dynamics. Discusses the treatment of fluid mechanics in physics curricula. Highlights a few of the problems of modern research in fluid dynamics. Shows that problems still remain. (CW)

  3. Early Work on Fluid Mechanics in The IC Engine

    NASA Astrophysics Data System (ADS)

    Lumley, John L.

    Early work of Ricardo is described, in which squish is used in flat-head engines to generate turbulence levels comparable to those in overhead-valve engines, leading to rapid flame propagation, and suppressing knock. Work by NACA before World War II is described, in which turbulence levels were measured in overhead-valve engines, indicating indirectly that surprisingly high levels were achieved just before ignition, possibly due to a tumble instability. Finally, work of Obukhov of 30 years ago is described, in which instabilities of tumbling flow are investigated in ellipsoids crudely modeling the engine cylinder as the piston rises; this suggests that there is an instability leading to intense small-scale motion just before ignition. Suggestions for further work are given.

  4. Mechanisms of fluid-flow-induced matrix production in bone tissue engineering.

    PubMed

    Morris, H L; Reed, C I; Haycock, J W; Reilly, G C

    2010-12-01

    Matrix production by tissue-engineered bone is enhanced when the growing tissue is subjected to mechanical forces and/or fluid flow in bioreactor culture. Cells deposit collagen and mineral, depending upon the mechanical loading that they receive. However, the molecular mechanisms of flow-induced signal transduction in bone are poorly understood. The hyaluronan (HA) glycocalyx has been proposed as a potential mediator of mechanical forces in bone. Using a parallel-plate flow chamber the effects of removal of HA on flow-induced collagen production and NF-kappaB activation in MLO-A5 osteoid osteocytes were investigated. Short periods of fluid flow significantly increased collagen production and induced translocation of the NF-kappaB subunit p65 to the cell's nuclei in 65 per cent of the cell population. Enzymatic removal of the HA coat and antibody blocking of CD44 (a transmembrane protein that binds to HA) eliminated the fluid-flow-induced increase in collagen production but had no effect on the translocation of p65. HA and CD44 appear to play roles in transducing the flow signals that modulate collagen production over long-term culture but not in the short-term flow-induced activation of NF-kappaB, implying that multiple signalling events are initiated from the commencement of flow. Understanding the mechanotransduction events that enable fluid flow to stimulate bone matrix production will allow the optimization of bioreactor design and flow profiles for bone tissue engineering.

  5. Institute for Mechanical Engineering

    NASA Astrophysics Data System (ADS)

    The Institute of Mechanical Engineering has the objectives of supporting in Canada the following activities: improvement of vehicles, propulsion systems, and transportation-related facilities and services; improvements in the design and operation of maritime engineering works; protection of the environment; enhancement of energy flexibility; advancement of firms engaged in manufacturing and resource extraction; and related programs of other government departments and agencies. In 1990-91 the Institute, which had changed its name that year from the Division of Mechanical Engineering, consolidated its research activities from nine laboratories to six programs. Activities in these six programs are described: Advanced Manufacturing Technology, Coastal Zone Engineering, Cold Regions Engineering, Combustion and Fluids Engineering, Ground Transportation Technology, and Machinery and Engine Technology.

  6. Achievements of engineering students on a fluid mechanics course in relation to the use of illustrative interactive simulations

    NASA Astrophysics Data System (ADS)

    Romero, Carlos; Martínez, Elvira

    2013-07-01

    Among other skills, a capacity for abstraction and good spatial awareness are needed to succeed in physics courses. According to the prevailing low percentages of passed students on these courses, a great proportion of those students are likely to lack these skills. Our working hypothesis is that simulations could help engineering students visualize physical phenomena and thereby gain a better understanding of physical theoretical concepts and achieve higher grades. Two groups of students (n1 = 40 and n2 = 43) took the same fluid mechanics course at an engineering school. Both groups took the same end-of-course examination, but only group 1 was simulation-taught. For that purpose, 15 original simulations were created with GeoGebra software. Simulation-taught students completed a questionnaire on the interest of using simulations to teach fluid mechanics. Simulations designed in this work covered all the concepts taught on the course and overcame criticisms made on previous simulations also created to teach fluid mechanics. At the examination, the average grade and the percentage of passed students were higher in group 1 than in group 2. When surveyed, group 1 students declared that they enjoyed interacting with the simulations and considered them to be a good complement to the theoretical explanations because simulations helped them revise previously explained concepts. Simulations assisted students with difficulties to visualize and understand physical theoretical concepts but still students performed poorly on the examination. Additional strategies need to be adopted in order to help students develop the skills required to succeed in physics courses.

  7. Mechanics of granular-frictional-visco-plastic fluids in civil and mining engineering

    NASA Astrophysics Data System (ADS)

    Alehossein, H.; Qin, Z.

    2013-10-01

    The shear stress generated in mine backfill slurries and fresh concrete contains both velocity gradient dependent and frictional terms, categorised as frictional viscous plastic fluids. This paper discusses application of the developed analytical solution for flow rate as a function of pressure and pressure gradient in discs, pipes and cones for such frictional Bingham-Herschel-Bulkley fluids. This paper discusses application of this continuum fluid model to industrial materials like mine and mineral slurries, backfills and fresh concrete tests.

  8. Enhancing the Connection to Undergraduate Engineering Students: A Hands-On and Team-Based Approach to Fluid Mechanics

    ERIC Educational Resources Information Center

    Wei, Tie; Ford, Julie

    2015-01-01

    This article provides information about the integration of innovative hands-on activities within a sophomore-level Fluid Mechanics course at New Mexico Tech. The course introduces students to the fundamentals of fluid mechanics with emphasis on teaching key equations and methods of analysis for solving real-world problems. Strategies and examples…

  9. Fluid Mechanics: The Pamphlet

    NASA Astrophysics Data System (ADS)

    Variano, Evan

    2012-11-01

    One impediment to student learning in introductory fluid mechanics courses is that the fundamental laws of physics can become lost in the ``noise'' of dozens of semi-empirical equations describing special cases. This can be exacerbated by trends in textbooks and other teaching media. This talk will explore a minimalist approach, whereby the entire content of introductory fluids is distilled to a single 1-page pamphlet, designed to emphasize the governing equations and their near-universal applicability. We are particularly interested in hearing feedback from the audience on ways to further distill the content while keeping it accessible and useful. To further emphasize the difference between the fundamental laws and the many specific cases, we have begun assembling a complementary resource: a field guide to fluid phenomena, which mixes the approach of Van Dyke's book with a standard field guide. This is designed to emphasize that there is a ``zoology'' of fluid phenomena, to which the same small set of fundamental laws has been applied repeatedly. These materials may be useful in helping AP Physics teachers cover fluid mechanics, which is an under-utilized opportunity to introduce young scientists to our field of study.

  10. Relativistic viscoelastic fluid mechanics.

    PubMed

    Fukuma, Masafumi; Sakatani, Yuho

    2011-08-01

    A detailed study is carried out for the relativistic theory of viscoelasticity which was recently constructed on the basis of Onsager's linear nonequilibrium thermodynamics. After rederiving the theory using a local argument with the entropy current, we show that this theory universally reduces to the standard relativistic Navier-Stokes fluid mechanics in the long time limit. Since effects of elasticity are taken into account, the dynamics at short time scales is modified from that given by the Navier-Stokes equations, so that acausal problems intrinsic to relativistic Navier-Stokes fluids are significantly remedied. We in particular show that the wave equations for the propagation of disturbance around a hydrostatic equilibrium in Minkowski space-time become symmetric hyperbolic for some range of parameters, so that the model is free of acausality problems. This observation suggests that the relativistic viscoelastic model with such parameters can be regarded as a causal completion of relativistic Navier-Stokes fluid mechanics. By adjusting parameters to various values, this theory can treat a wide variety of materials including elastic materials, Maxwell materials, Kelvin-Voigt materials, and (a nonlinearly generalized version of) simplified Israel-Stewart fluids, and thus we expect the theory to be the most universal description of single-component relativistic continuum materials. We also show that the presence of strains and the corresponding change in temperature are naturally unified through the Tolman law in a generally covariant description of continuum mechanics.

  11. Lord Kelvin on fluid mechanics

    NASA Astrophysics Data System (ADS)

    Craik, Alex D. D.

    2012-06-01

    William Thomson, Baron Kelvin of Largs, was the best-known British scientist of his day, who made fundamental contributions to many areas of physics and engineering. Though his life and work have been much studied, his contributions to fluid mechanics have received far less attention that those in heat, electricity, magnetism, geophysics, "ether theory" and telegraphy. After a general introduction, Kelvin's writings on fluid mechanics are comprehensively surveyed. These reveal the interplay of his mathematical expertise and physical intuition, his deployment of physical analogies, and the origins of some of his work in later-abandoned speculations. Among lasting contributions are his circulation theorem and minimum energy theorem, the misnamed "Stokes' theorem", a generalization of Green's theorem, the method of stationary phase, and much on vortices, instabilities, tides and water waves.

  12. Fluid mechanics in fluids at rest.

    PubMed

    Brenner, Howard

    2012-07-01

    Using readily available experimental thermophoretic particle-velocity data it is shown, contrary to current teachings, that for the case of compressible flows independent dye- and particle-tracer velocity measurements of the local fluid velocity at a point in a flowing fluid do not generally result in the same fluid velocity measure. Rather, tracer-velocity equality holds only for incompressible flows. For compressible fluids, each type of tracer is shown to monitor a fundamentally different fluid velocity, with (i) a dye (or any other such molecular-tagging scheme) measuring the fluid's mass velocity v appearing in the continuity equation and (ii) a small, physicochemically and thermally inert, macroscopic (i.e., non-Brownian), solid particle measuring the fluid's volume velocity v(v). The term "compressibility" as used here includes not only pressure effects on density, but also temperature effects thereon. (For example, owing to a liquid's generally nonzero isobaric coefficient of thermal expansion, nonisothermal liquid flows are to be regarded as compressible despite the general perception of liquids as being incompressible.) Recognition of the fact that two independent fluid velocities, mass- and volume-based, are formally required to model continuum fluid behavior impacts on the foundations of contemporary (monovelocity) fluid mechanics. Included therein are the Navier-Stokes-Fourier equations, which are now seen to apply only to incompressible fluids (a fact well-known, empirically, to experimental gas kineticists). The findings of a difference in tracer velocities heralds the introduction into fluid mechanics of a general bipartite theory of fluid mechanics, bivelocity hydrodynamics [Brenner, Int. J. Eng. Sci. 54, 67 (2012)], differing from conventional hydrodynamics in situations entailing compressible flows and reducing to conventional hydrodynamics when the flow is incompressible, while being applicable to both liquids and gases.

  13. Fluid mechanics in fluids at rest

    NASA Astrophysics Data System (ADS)

    Brenner, Howard

    2012-07-01

    Using readily available experimental thermophoretic particle-velocity data it is shown, contrary to current teachings, that for the case of compressible flows independent dye- and particle-tracer velocity measurements of the local fluid velocity at a point in a flowing fluid do not generally result in the same fluid velocity measure. Rather, tracer-velocity equality holds only for incompressible flows. For compressible fluids, each type of tracer is shown to monitor a fundamentally different fluid velocity, with (i) a dye (or any other such molecular-tagging scheme) measuring the fluid's mass velocity v appearing in the continuity equation and (ii) a small, physicochemically and thermally inert, macroscopic (i.e., non-Brownian), solid particle measuring the fluid's volume velocity vv. The term “compressibility” as used here includes not only pressure effects on density, but also temperature effects thereon. (For example, owing to a liquid's generally nonzero isobaric coefficient of thermal expansion, nonisothermal liquid flows are to be regarded as compressible despite the general perception of liquids as being incompressible.) Recognition of the fact that two independent fluid velocities, mass- and volume-based, are formally required to model continuum fluid behavior impacts on the foundations of contemporary (monovelocity) fluid mechanics. Included therein are the Navier-Stokes-Fourier equations, which are now seen to apply only to incompressible fluids (a fact well-known, empirically, to experimental gas kineticists). The findings of a difference in tracer velocities heralds the introduction into fluid mechanics of a general bipartite theory of fluid mechanics, bivelocity hydrodynamics [Brenner, Int. J. Eng. Sci.10.1016/j.ijengsci.2012.01.006 54, 67 (2012)], differing from conventional hydrodynamics in situations entailing compressible flows and reducing to conventional hydrodynamics when the flow is incompressible, while being applicable to both liquids and

  14. Start Up Research Effort in Fluid Mechanics. Advanced Methods for Acoustic and Thrust Benefits for Aircraft Engine Nozzle

    NASA Technical Reports Server (NTRS)

    White, Samuel G.; Gilinsky, Mikhail M.

    1997-01-01

    In accordance with the project plan for the report period in the proposal titled above, HU and FML teams investigated two sets of concepts for reduction of noise and improvement in efficiency for jet exhaust nozzles of aircraft engines and screws for mixers, fans, propellers and boats. The main achievements in the report period are: (a) Publication of the paper in the AIAA Journal, which described our concepts and some results. (b) The Award in the Civil Research and Development Foundation (CRDF) competition. This 2 year grant for Hampton University (HU) and Central AeroHydrodynamic Institute (TSAGI, Moscow, Russia) supports the research implementation under the current NASA FAR grant. (c) Selection for funding by NASA HQ review panel of the Partnership Awards Concept Paper. This two year grant also will support our current FAR grant. (d) Publication of a Mobius Strip concept in NASA Technical Briefs, June, 1996, and a great interest of many industrial companies in this invention. Successful experimental results with the Mobius shaped screw for mixers, which save more than 30% of the electric power by comparison with the standard screws. Creation of the scientific-popular video-film which can be used for commercial and educational purposes. (e) Organization work, joint meetings and discussions of the NASA LARC JNL Team and HU professors and administration for the solution of actual problems and effective work of the Fluid Mechanics Laboratory at Hampton University. In this report the main designs are enumerated. It also contains for both concept sets: (1) the statement of the problem for each design, some results, publications, inventions, patents, our vision for continuation of this research, and (2) present and expected problems in the future.

  15. Selected topics of fluid mechanics

    USGS Publications Warehouse

    Kindsvater, Carl E.

    1958-01-01

    The fundamental equations of fluid mechanics are specific expressions of the principles of motion which are ascribed to Isaac Newton. Thus, the equations which form the framework of applied fluid mechanics or hydraulics are, in addition to the equation of continuity, the Newtonian equations of energy and momentum. These basic relationships are also the foundations of river hydraulics. The fundamental equations are developed in this report with sufficient rigor to support critical examinations of their applicability to most problems met by hydraulic engineers of the Water Resources Division of the United States Geological Survey. Physical concepts are emphasized, and mathematical procedures are the simplest consistent with the specific requirements of the derivations. In lieu of numerical examples, analogies, and alternative procedures, this treatment stresses a brief methodical exposition of the essential principles. An important objective of this report is to prepare the user to read the literature of the science. Thus, it begins With a basic vocabulary of technical symbols, terms, and concepts. Throughout, emphasis is placed on the language of modern fluid mechanics as it pertains to hydraulic engineering. The basic differential and integral equations of simple fluid motion are derived, and these equations are, in turn, used to describe the essential characteristics of hydrostatics and piezometry. The one-dimensional equations of continuity and motion are defined and are used to derive the general discharge equation. The flow net is described as a means of demonstrating significant characteristics of two-dimensional irrotational flow patterns. A typical flow net is examined in detail. The influence of fluid viscosity is described as an obstacle to the derivation of general, integral equations of motion. It is observed that the part played by viscosity is one which is usually dependent on experimental evaluation. It follows that the dimensionless ratios known as

  16. 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.

  17. Physics of Mechanical, Gaseous, and Fluid Systems. A Study Guide of the Science and Engineering Technician Curriculum.

    ERIC Educational Resources Information Center

    Dixon, Peggy; And Others

    This study guide is part of a program of studies entitled Science and Engineering Technician (SET) Curriculum. The SET Curriculum integrates elements from the disciplines of chemistry, physics, mathematics, mechanical technology, and electronic technology. The objective of this curriculum development project is to train technicians in the use of…

  18. Respiratory fluid mechanics

    NASA Astrophysics Data System (ADS)

    Grotberg, James B.

    2011-02-01

    This article covers several aspects of respiratory fluid mechanics that have been actively investigated by our group over the years. For the most part, the topics involve two-phase flows in the respiratory system with applications to normal and diseased lungs, as well as therapeutic interventions. Specifically, the topics include liquid plug flow in airways and at airway bifurcations as it relates to surfactant, drug, gene, or stem cell delivery into the lung; liquid plug rupture and its damaging effects on underlying airway epithelial cells as well as a source of crackling sounds in the lung; airway closure from "capillary-elastic instabilities," as well as nonlinear stabilization from oscillatory core flow which we call the "oscillating butter knife;" liquid film, and surfactant dynamics in an oscillating alveolus and the steady streaming, and surfactant spreading on thin viscous films including our discovery of the Grotberg-Borgas-Gaver shock.

  19. Respiratory fluid mechanics

    PubMed Central

    Grotberg, James B.

    2011-01-01

    This article covers several aspects of respiratory fluid mechanics that have been actively investigated by our group over the years. For the most part, the topics involve two-phase flows in the respiratory system with applications to normal and diseased lungs, as well as therapeutic interventions. Specifically, the topics include liquid plug flow in airways and at airway bifurcations as it relates to surfactant, drug, gene, or stem cell delivery into the lung; liquid plug rupture and its damaging effects on underlying airway epithelial cells as well as a source of crackling sounds in the lung; airway closure from “capillary-elastic instabilities,” as well as nonlinear stabilization from oscillatory core flow which we call the “oscillating butter knife;” liquid film, and surfactant dynamics in an oscillating alveolus and the steady streaming, and surfactant spreading on thin viscous films including our discovery of the Grotberg–Borgas–Gaver shock. PMID:21403768

  20. Respiratory fluid mechanics.

    PubMed

    Grotberg, James B

    2011-02-01

    This article covers several aspects of respiratory fluid mechanics that have been actively investigated by our group over the years. For the most part, the topics involve two-phase flows in the respiratory system with applications to normal and diseased lungs, as well as therapeutic interventions. Specifically, the topics include liquid plug flow in airways and at airway bifurcations as it relates to surfactant, drug, gene, or stem cell delivery into the lung; liquid plug rupture and its damaging effects on underlying airway epithelial cells as well as a source of crackling sounds in the lung; airway closure from "capillary-elastic instabilities," as well as nonlinear stabilization from oscillatory core flow which we call the "oscillating butter knife;" liquid film, and surfactant dynamics in an oscillating alveolus and the steady streaming, and surfactant spreading on thin viscous films including our discovery of the Grotberg-Borgas-Gaver shock.

  1. Applied Fluid Mechanics. Lecture Notes.

    ERIC Educational Resources Information Center

    Gregg, Newton D.

    This set of lecture notes is used as a supplemental text for the teaching of fluid dynamics, as one component of a thermodynamics course for engineering technologists. The major text for the course covered basic fluids concepts such as pressure, mass flow, and specific weight. The objective of this document was to present additional fluids…

  2. Designing and Creating a Set of New Lab Experiments for a Traditional Fluid Mechanics Course in Civil Engineering

    NASA Astrophysics Data System (ADS)

    Budny, Dan

    2013-11-01

    Many fluids lab facilities and their associated student experiences were built back in the 1960-1970 time frames. They typically consisted of large facilities that included wind tunnels, flumes, wet wells, pump stations, etc. Today these labs are physically and pedagogically out dated and the need for lab space is forcing the closing of large scale labs. This is the same basic problem within the Swanson School of Engineering at the University of Pittsburgh. Thus we have replaced all the old equipment and lab experiences with small bench top experiments with a focus on applying the large body of knowledge associate with better student learning experiences. This paper will describe the concepts behind the design of the new experiments and the learning improvements discovered as a result of moving from a few large experiments to a larger number of smaller scale experiments.

  3. The Mechanism of Fluid Resistance

    NASA Technical Reports Server (NTRS)

    Vonkarman, T.; Rubach, H.

    1979-01-01

    The mechanism of fluid resistance within the limit of the square law is presented. It was concluded that the investigations should be extended and completed in two directions, namely: by an investigation of stable vortex configurations in space, and by considering the perfect fluid as the limiting case of a viscous fluid and then limiting the law of vortex of formation with the condition that only those fluid particles which were in contact with the surface of the body can receive rotation.

  4. Indicators of Student Engagement in Fluid Mechanics

    NASA Astrophysics Data System (ADS)

    Hertzberg, Jean; Goodman, Katherine

    2015-11-01

    Many engineering programs require a fluids course. Standards such as ABET ensure that it is technically accurate. To keep students engaged, however, we need to ask: does this course present our discipline in its most salient and meaningful form? As part of an ongoing investigation of a technical elective called Flow Visualization, we compare student surveys from both Flow Vis and a required Fluid Mechanics course. Surveys going back to 2008-2012 found that Fluid Mechanics students in Mechanical Engineering at the University of Colorado Boulder tended to have a negative shift in affect. That is, they were less likely to believe studying fluids was important to them as engineers and to society in general by the end of the course. More recent surveys find that this has become neutral among our students: from the beginning to the end of the course, they do not report any change in the importance of fluids. The recent survey also reveals that they are now noticing fluids in everyday life significantly more often. This expanded perception is a hallmark of the Deweyan transformative experience, a framework to evaluate the motivational and affective aspects of a course. Suggestions of why these changes have taken place are drawn from open-response survey items and student interviews. This material is based upon work supported by the National Science Foundation under Grant No. EC-1240294.

  5. Numerical Study of Granular Scaffold Efficiency to Convert Fluid Flow into Mechanical Stimulation in Bone Tissue Engineering.

    PubMed

    Cruel, Magali; Bensidhoum, Morad; Nouguier-Lehon, Cécile; Dessombz, Olivier; Becquart, Pierre; Petite, Hervé; Hoc, Thierry

    2015-09-01

    Controlling the mechanical environment in bioreactors represents a key element in the reactors' optimization. Positive effects of fluid flow in three-dimensional bioreactors have been observed, but local stresses at cell scale remain unknown. These effects led to the development of numerical tools to assess the micromechanical environment of cells in bioreactors. Recently, new possible scaffold geometry has emerged: granular packings. In the present study, the primary goal was to compare the efficiency of such a scaffold to the other ones from literature in terms of wall shear stress levels and distributions. To that aim, three different types of granular packings were generated through discrete element method, and computational fluid dynamics was used to simulate the flow within these packings. Shear stress levels and distributions were determined. A linear relationship between shear stress and inlet velocity was observed, and its slope was similar to published data. The distributions of normalized stress were independent of the inlet velocity and were highly comparable to those of widely used porous scaffolds. Granular packings present similar features to more classical porous scaffolds and have the advantage of being easy to manipulate and seed. The methods of this work are generalizable to the study of other granular packing configurations.

  6. On the fluid mechanics of fires

    SciTech Connect

    TIESZEN,SHELDON R.

    2000-02-29

    Fluid mechanics research related to fire is reviewed with focus on canonical flows, multiphysics coupling aspects, experimental and numerical techniques. Fire is a low-speed, chemically-reacting, flow in which buoyancy plans an important role. Fire research has focused on two canonical flows, the reacting boundary-layer and the reacting free plume. There is rich, multi-lateral, bi-directional, coupling among fluid mechanics and scalar transport, combustion, and radiation. There is only a limited experimental fluid-mechanics database for fire due to measurement difficulties in the harsh environment, and the focus within the fire community on thermal/chemical consequences. Increasingly, computational fluid dynamics techniques are being used to provide engineering guidance on thermal/chemical consequences and to study fire phenomenology.

  7. Wentworth Institute Mechanical Engineering Laboratory Manual.

    ERIC Educational Resources Information Center

    Avakian, Harry; And Others

    This publication is a Mechanical Engineering Laboratory Manual designed to be used by technical institute students in Mechanical Engineering Technology Programs. The experiments are introductory in nature and embrace the fields of applied thermodynamics, fluid mechanics, refrigeration, heat transfer and basic instrumentation. There are 20…

  8. 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.

  9. Nanoscale Fluid Mechanics and Energy Conversion

    SciTech Connect

    Chen, X; Xu, BX; Liu, L

    2014-05-29

    Under nanoconfinement, fluid molecules and ions exhibit radically different configurations, properties, and energetics from those of their bulk counterparts. These unique characteristics of nanoconfined fluids, along with the unconventional interactions with solids at the nanoscale, have provided many opportunities for engineering innovation. With properly designed nanoconfinement, several nanofluidic systems have been devised in our group in the past several years to achieve energy conversion functions with high efficiencies. This review is dedicated to elucidating the unique characteristics of nanofluidics, introducing several novel nanofluidic systems combining nanoporous materials with functional fluids, and to unveiling their working mechanisms. In all these systems, the ultra-large surface area available in nanoporous materials provides an ideal platform for seamlessly interfacing with nanoconfined fluids, and efficiently converting energy between the mechanical, thermal, and electrical forms. These systems have been demonstrated to have great potentials for applications including energy dissipation/absorption, energy trapping, actuation, and energy harvesting. Their efficiencies can be further enhanced by designing efforts based upon improved understanding of nanofluidics, which represents an important addition to classical fluid mechanics. Through the few systems exemplified in this review, the emerging research field of nanoscale fluid mechanics may promote more exciting nanofluidic phenomena and mechanisms, with increasing applications by encompassing aspects of mechanics, materials, physics, chemistry, biology, etc.

  10. Galilean relativistic fluid mechanics

    NASA Astrophysics Data System (ADS)

    Ván, P.

    2017-01-01

    Single-component nonrelativistic dissipative fluids are treated independently of reference frames and flow-frames. First the basic fields and their balances are derived, then the related thermodynamic relations and the entropy production are calculated and the linear constitutive relations are given. The usual basic fields of mass, momentum, energy and their current densities, the heat flux, pressure tensor and diffusion flux are the time- and spacelike components of the third-order mass-momentum-energy density-flux four-tensor. The corresponding Galilean transformation rules of the physical quantities are derived. It is proved that the non-equilibrium thermodynamic frame theory, including the thermostatic Gibbs relation and extensivity condition and also the entropy production, is independent of the reference frame and also the flow-frame of the fluid. The continuity-Fourier-Navier-Stokes equations are obtained almost in the traditional form if the flow of the fluid is fixed to the temperature. This choice of the flow-frame is the thermo-flow. A simple consequence of the theory is that the relation between the total, kinetic and internal energies is a Galilean transformation rule.

  11. Galilean relativistic fluid mechanics

    NASA Astrophysics Data System (ADS)

    Ván, P.

    2017-03-01

    Single-component nonrelativistic dissipative fluids are treated independently of reference frames and flow-frames. First the basic fields and their balances are derived, then the related thermodynamic relations and the entropy production are calculated and the linear constitutive relations are given. The usual basic fields of mass, momentum, energy and their current densities, the heat flux, pressure tensor and diffusion flux are the time- and spacelike components of the third-order mass-momentum-energy density-flux four-tensor. The corresponding Galilean transformation rules of the physical quantities are derived. It is proved that the non-equilibrium thermodynamic frame theory, including the thermostatic Gibbs relation and extensivity condition and also the entropy production, is independent of the reference frame and also the flow-frame of the fluid. The continuity-Fourier-Navier-Stokes equations are obtained almost in the traditional form if the flow of the fluid is fixed to the temperature. This choice of the flow-frame is the thermo-flow. A simple consequence of the theory is that the relation between the total, kinetic and internal energies is a Galilean transformation rule.

  12. Fluid Mechanics Can Be Fun.

    ERIC Educational Resources Information Center

    Blanks, Robert F.

    1979-01-01

    A humanistic approach to teaching fluid mechanics is described which minimizes lecturing, increases professor-student interaction, uses group and individual problem solving sessions, and allows for student response. (BB)

  13. Ann Wagner, Mechanical Engineer.

    ERIC Educational Resources Information Center

    Bennett, Betsy K.

    1996-01-01

    Presents a profile of Ann Wagner, a mechanical engineer at the Goddard Space Flight Center in Maryland, and her job responsibilities there. Also includes a brief history of mechanical engineering as well as a sample graph and data activity sheet with answers. (AIM)

  14. PREFACE: XXI Fluid Mechanics Conference

    NASA Astrophysics Data System (ADS)

    Szmyd, Janusz S.; Fornalik-Wajs, Elzbieta; Jaszczur, Marek

    2014-08-01

    This Conference Volume contains the papers presented at the 21st Fluid Mechanics Conference (XXI FMC) held at AGH - University of Science and Technology in Krakow, Poland, 15-18 June 2014, and accepted for Proceedings published in the Journal of Physics: Conference Series. The Fluid Mechanics Conferences have been taking place every two years since 1974, a total of forty years. The 21st Fluid Mechanics Conference (XXI FMC) is being organized under the auspices of the Polish Academy of Sciences, Committee of Mechanics. The goal of this conference is to provide a forum for the exposure and exchange of ideas, methods and results in fluid mechanics. Conference topics include, but are not limited to Aerodynamics, Atmospheric Science, Bio-Fluids, Combustion and Reacting Flows, Computational Fluid Dynamics, Experimental Fluid Mechanics, Flow Machinery, General Fluid Dynamics, Hydromechanics, Heat and Fluid Flow, Measurement Techniques, Micro- and Nano- Flow, Multi-Phase Flow, Non-Newtonian Fluids, Rotating and Stratified Flows, Turbulence. Within the general subjects of this conference, the Professor Janusz W. Elsner Competition for the best fluid mechanics paper presented during the Conference is organized. Authors holding a M.Sc. or a Ph.D. degree and who are not older than 35 years of age may enter the Competition. Authors with a Ph.D. degree must present individual papers; authors with a M.Sc. degree may present papers with their supervisor as coauthor, including original results of experimental, numerical or analytic research. Six state-of-the-art keynote papers were delivered by world leading experts. All contributed papers were peer reviewed. Recommendations were received from the International Scientific Committee, reviewers and the advisory board. Accordingly, of the 163 eligible extended abstracts submitted, after a review process by the International Scientific Committee, 137 papers were selected for presentation at the 21st Fluid Mechanics Conference, 68

  15. Fluid Mechanics of Taste

    NASA Astrophysics Data System (ADS)

    Noel, Alexis; Bhatia, Nitesh; Carter, Taren; Hu, David

    2015-11-01

    Saliva plays a key role in digestion, speech and tactile sensation. Lack of saliva, also known as dry mouth syndrome, increases risk of tooth decay and alters sense of taste; nearly 10% of the general population suffer from this syndrome. In this experimental study, we investigate the spreading of water drops on wet and dry tongues of pigs and cows. We find that drops spread faster on a wet tongue than a dry tongue. We rationalize the spreading rate by consideration of the tongue microstructure, such as as papillae, in promoting wicking. By investigating how tongue microstructure affects spreading of fluids, we may begin to how understand taste receptors are activated by eating and drinking.

  16. Attracting Students to Fluid Mechanics with Coffee

    NASA Astrophysics Data System (ADS)

    Ristenpart, William

    2016-11-01

    We describe a new class developed at U.C. Davis titled "The Design of Coffee," which serves as a nonmathematical introduction to chemical engineering as illustrated by the process of roasting and brewing coffee. Hands-on coffee experiments demonstrate key engineering principles, including material balances, chemical kinetics, mass transfer, conservation of energy, and fluid mechanics. The experiments lead to an engineering design competition where students strive to make the best tasting coffee using the least amount of energy - a classic engineering optimization problem, but one that is both fun and tasty. "The Design of Coffee" started as a freshmen seminar in 2013, and it has exploded in popularity: it now serves 1,533 students per year, and is the largest and most popular elective course at U.C. Davis. In this talk we focus on the class pedagogy as applied to fluid mechanics, with an emphasis on how coffee serves as an engaging and exciting topic for teaching students about fluid mechanics in an approachable, hands-on manner.

  17. Basic Engineer Equipment Mechanic.

    ERIC Educational Resources Information Center

    Marine Corps Inst., Washington, DC.

    This student guide, one of a series of correspondence training courses designed to improve the job performance of members of the Marine Corps, deals with the skills needed by basic engineer equipment mechanics. Addressed in the four individual units of the course are the following topics: mechanics and their tools (mechanics, hand tools, and power…

  18. Fluid mechanics of heart valves.

    PubMed

    Yoganathan, Ajit P; He, Zhaoming; Casey Jones, S

    2004-01-01

    Valvular heart disease is a life-threatening disease that afflicts millions of people worldwide and leads to approximately 250,000 valve repairs and/or replacements each year. Malfunction of a native valve impairs its efficient fluid mechanic/hemodynamic performance. Artificial heart valves have been used since 1960 to replace diseased native valves and have saved millions of lives. Unfortunately, despite four decades of use, these devices are less than ideal and lead to many complications. Many of these complications/problems are directly related to the fluid mechanics associated with the various mechanical and bioprosthetic valve designs. This review focuses on the state-of-the-art experimental and computational fluid mechanics of native and prosthetic heart valves in current clinical use. The fluid dynamic performance characteristics of caged-ball, tilting-disc, bileaflet mechanical valves and porcine and pericardial stented and nonstented bioprostheic valves are reviewed. Other issues related to heart valve performance, such as biomaterials, solid mechanics, tissue mechanics, and durability, are not addressed in this review.

  19. Respiratory Fluid Mechanics

    NASA Astrophysics Data System (ADS)

    Grotberg, James

    2005-11-01

    This brief overview of our groups activities includes liquid plug propagation in single and bifurcating tubes, a subject which pertains to surfactant delivery, liquid ventilation, pulmonary edema, and drowning. As the plug propagates, a variety of flow patterns may emerge depending on the parameters. It splits unevenly at airway bifurcations and can rupture, which reopens the airway to gas flow. Both propagation and rupture may damage the underlying airway wall cells. Another topic is surfactant dynamics and flow in a model of an oscillating alveolus. The analysis shows a nontrivial cycle-averaged surfactant concentration gradient along the interface that generates steady streaming. The steady streaming patterns particularly depend on the ratio of inspiration to expiration time periods and the sorption parameter. Vortices, single and multiple, may be achieved, as well as a saddle point configuration. Potential applications are pulmonary drug administration, cell-cell signaling pathways, and gene therapy. Finally, capillary instabilities which cause airway closure, and strategies for stabilization, will be presented. This involves the core-annular flow of a liquid-lined tube, where the core (air) is forced to oscillate axially. The stabilization mechanism is similar to that of a reversing butter knife, where the core shear wipes the growing liquid bulge, from the Rayleigh instability, back on to the tube wall during the main tidal volume stroke, but allows it to grow back as the stroke and shear turn around.

  20. Stirling engine with air working fluid

    DOEpatents

    Corey, John A.

    1985-01-01

    A Stirling engine capable of utilizing air as a working fluid which includes a compact heat exchange module which includes heating tube units, regenerator and cooler positioned about the combustion chamber. This arrangement has the purpose and effect of allowing the construction of an efficient, high-speed, high power-density engine without the use of difficult to seal light gases as working fluids.

  1. Fluid Mechanics in Sommerfeld's School

    NASA Astrophysics Data System (ADS)

    Eckert, Michael

    2015-01-01

    Sommerfeld's affiliation with fluid mechanics started when he began his career as an assistant of the mathematician Felix Klein at Göttingen. He always regarded fluid mechanics as a particular challenge. In 1904, he published a theory of hydrodynamic lubrication. Four years later, he conceived an approach for the analysis of flow instability (the Orr-Sommerfeld approach) as an attempt to account for the transition from laminar to turbulent flow. The onset of turbulence also became a major challenge for some of his pupils, in particular Ludwig Hopf and Fritz Noether. Both contributed considerably to elaborate the Orr-Sommerfeld theory. Heisenberg's doctoral work was another attempt in this quest. When Sommerfeld published his lectures on theoretical physics during World War II, he dedicated one of the six volumes to the mechanics of continuous media. With chapters on boundary layer theory and turbulence, it exceeded the scope of contemporary theoretical physics—revealing Sommerfeld's persistent appreciation of fluid mechanics. He resorted to Prandtl's Göttingen school of fluid mechanics in order to stay abreast of the rapid development of these specialties.

  2. Engineer Equipment Mechanic.

    ERIC Educational Resources Information Center

    Marine Corps Inst., Washington, DC.

    Developed as part of the Marine Corps Institute (MCI) correspondence training program, this course on engineer equipment mechanics is designed to advance the professional competence of privates through sergeants as equipment mechanics, Military Occupation Specialty 1341, and is adaptable for nonmilitary instruction. Introductory materials include…

  3. Engineering fluid flow using sequenced microstructures

    NASA Astrophysics Data System (ADS)

    Amini, Hamed; Sollier, Elodie; Masaeli, Mahdokht; Xie, Yu; Ganapathysubramanian, Baskar; Stone, Howard A.; di Carlo, Dino

    2013-05-01

    Controlling the shape of fluid streams is important across scales: from industrial processing to control of biomolecular interactions. Previous approaches to control fluid streams have focused mainly on creating chaotic flows to enhance mixing. Here we develop an approach to apply order using sequences of fluid transformations rather than enhancing chaos. We investigate the inertial flow deformations around a library of single cylindrical pillars within a microfluidic channel and assemble these net fluid transformations to engineer fluid streams. As these transformations provide a deterministic mapping of fluid elements from upstream to downstream of a pillar, we can sequentially arrange pillars to apply the associated nested maps and, therefore, create complex fluid structures without additional numerical simulation. To show the range of capabilities, we present sequences that sculpt the cross-sectional shape of a stream into complex geometries, move and split a fluid stream, perform solution exchange and achieve particle separation. A general strategy to engineer fluid streams into a broad class of defined configurations in which the complexity of the nonlinear equations of fluid motion are abstracted from the user is a first step to programming streams of any desired shape, which would be useful for biological, chemical and materials automation.

  4. [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.

  5. 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.

  6. Engine & Vehicle Mechanics Curriculum.

    ERIC Educational Resources Information Center

    Alaska State Dept. of Education, Juneau. Div. of Adult and Vocational Education.

    This competency-based curriculum includes all competencies a student will acquire in an engine and vehicle mechanics educational program. It follows guidelines established for automobile technician training programs leading toward certification and addresses requirements of the National Institute for Automotive Service Excellence (ASE). The…

  7. Turbomachinery Fluid Mechanics and Control

    DTIC Science & Technology

    2010-01-01

    side, thereby limiting the achievable flow. Further numerical studies were completed to improve the flow field performance in the internal passages...Shear Layers”, Journal of Fluid Mechanics , 1996, 308: 63-96 7. M. R. Van der Veer and P. J. Strykowski, “Counterflow Thrust Vector Control of...particularly for highly loaded blade rows, can be very complex and requires systematic study . In the work described here, experimental

  8. 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.

  9. Selection of software for mechanical engineering undergraduates

    NASA Astrophysics Data System (ADS)

    Cheah, C. T.; Yin, C. S.; Halim, T.; Naser, J.; Blicblau, A. S.

    2016-07-01

    A major problem with the undergraduate mechanical course is the limited exposure of students to software packages coupled with the long learning curve on the existing software packages. This work proposes the use of appropriate software packages for the entire mechanical engineering curriculum to ensure students get sufficient exposure real life design problems. A variety of software packages are highlighted as being suitable for undergraduate work in mechanical engineering, e.g. simultaneous non-linear equations; uncertainty analysis; 3-D modeling software with the FEA; analysis tools for the solution of problems in thermodynamics, fluid mechanics, mechanical system design, and solid mechanics.

  10. History of the Fluids Engineering Division

    DOE PAGES

    Cooper, Paul; Martin, C. Samuel; O'Hern, Timothy J.

    2016-08-03

    The 90th Anniversary of the Fluids Engineering Division (FED) of ASME will be celebrated on July 10–14, 2016 in Washington, DC. The venue is ASME's Summer Heat Transfer Conference (SHTC), Fluids Engineering Division Summer Meeting (FEDSM), and International Conference on Nanochannels and Microchannels (ICNMM). The occasion is an opportune time to celebrate and reflect on the origin of FED and its predecessor—the Hydraulic Division (HYD), which existed from 1926–1963. Furthermore, the FED Executive Committee decided that it would be appropriate to publish concurrently a history of the HYD/FED.

  11. Mechanical engineering in hospitals.

    PubMed

    Wallington, J W

    1980-10-01

    The design of a modern hospital owes more to engineering than the layman may realize. In this context, many engineers are in the position of laymen, being unfamiliar with the multitude of services that lies behind the impressive facade of a modern hospital. In recent years medicine and surgery themselves have taken on many of the characteristics of a technology. This has required a matching development of the services both mechanical and electrical that are required in modern health care buildings. In medical terms, if the architectural features provide the 'skin' of the hospital, the mechanical and electrical engineering services provide the nerves and sinews. If we take as an example the recently completed Freeman Hospital, Newcastle upon Tyne, (Fig. 1), which cost 10 million pounds at current cost, the service network was responsible for about half the total cost. About 400 miles (643 km) of electrical wiring and more than 40 mile (64.5 km) of copper and steel piping were used to service 3000 separate rooms. This compares with percentages of between 18 and 25 per cent for other large buildings such as office blocks, hotels and sports complexes.

  12. Tracing Injection Fluids in Engineered Geothermal Systems

    NASA Astrophysics Data System (ADS)

    Rose, P. E.; Leecaster, K.; Mella, M.; Ayling, B.; Bartl, M. H.

    2011-12-01

    The reinjection of produced fluids is crucial to the effective management of geothermal reservoirs, since it provides a mechanism for maintaining reservoir pressures while allowing for the disposal of a toxic byproduct. Tracers are essential to the proper location of injection wells since they are the only known tool for reliably characterizing the flow patterns of recirculated fluids. If injection wells are placed too close to production wells, then reinjected fluids do not have sufficient residence time to extract heat from the reservoir and premature thermal breakthrough results. If injection wells are placed too far away, then the reservoir risks unacceptable pressure loss. Several thermally stable compounds from a family of very detectable fluorescent organic compounds (the naphthalene sulfonates) were characterized and found to be effective for use as geothermal tracers. Through batch-autoclave reactions, their Arrhenius pseudo-first-order decay-rate constants were determined. An analytical method was developed that allows for the laboratory determination of concentrations in the low parts-per-trillion range. Field experiments in numerous geothermal reservoirs throughout the world have confirmed the laboratory findings. Whereas conservative tracers such as the naphthalene sulfonates are effective tools for indicating interwell flow patterns and for measuring reservoir pore volumes, 'reactive' tracers can be used to constrain fracture surface area, which is the effective area for heat extraction. This is especially important for engineered geothermal system (EGS) wells, since reactive tracers can be used to measure fracture surface area immediately after drilling and while the well stimulation equipment is still on site. The reactive properties of these tracers that can be exploited to constrain fracture surface area are reversible sorption, contrasting diffusivity, and thermal decay. Laboratory batch- and flow-reactor experiments in combination with numerical

  13. Fluid Mechanics of Urban Environments

    NASA Astrophysics Data System (ADS)

    Fernando, Harindra J.

    2008-11-01

    The rapid urbanization of the Earth has led to highly populated cities that act as concentrated centers of anthropogenic stressors on the natural environment. The degradation of environmental quality due to such stressors, in turn, greatly impacts human behavior. Anthropogenic stressors largely originate as a result of coupling between man-made urban elements (i.e., networks of engineering and socio-economic infrastructures) and the environment, for which surrounding fluid motions play a key role. In recent years, research efforts have been directed at the understanding and modeling of fluid motions in urban areas, infrastructure dynamics and interactions thereof, with the hope of identifying environmental impacts of urbanization and complex outcomes (or ``emergent properties'') of nominally simple interactions between infrastructures and environment. Such consequences play an important role in determining the ``resilience'' of cities under anthropogenic stressors, defined as maintaining the structure and essential functions of an urbanity without regime shifts. Holistic integrated models that meld the dynamics of infrastructures and environment as well as ``quality of life'' attributes are becoming powerful decision-making tools with regard to sustainability of urban areas (continuance or even enhancement of socio-economic activities in harmony with the environment). The rudimentary forms of integrated models are beginning to take shape, augmented by comprehensive field studies and advanced measurement platforms to validate them. This presentation deals with the challenges of modeling urban atmosphere, subject to anthropogenic forcing. An important emergent property, the Urban Heat Island, and its role in determining resilience and sustainability of cities will be discussed based on the prediction of a coupled model.

  14. Activities of the Institute for Mechanical Engineering

    NASA Astrophysics Data System (ADS)

    The Institute of Mechanical Engineering (IME) is part of Canada's National Research Council. Its mission is to undertake, support, promote, and disseminate research and development in the mechanical engineering aspects of three vital sectors of the Canadian economy: transportation, resource industries, and manufacturing. The IME achieves its mission by performing research and development in its own facilities; by developing, providing, and transferring expertise and knowledge; by making its research facilities available to collaborators and clients; and by participating in international liaison and collaborative research activities. Six research programs are conducted in the IME: Advanced Manufacturing Technology; Coastal Zone Engineering; Cold Regions Engineering; Combustion and Fluids Engineering; Ground Transportation Technology; and Machinery and Engine Technology. The rationale and major research thrusts of each program are described, and specific achievements in 1991-92 are reviewed. Lists of technical reports and papers presented by IME personnel are also included.

  15. Fluid Mechanics Optimising Organic Synthesis

    NASA Astrophysics Data System (ADS)

    Leivadarou, Evgenia; Dalziel, Stuart

    2015-11-01

    The Vortex Fluidic Device (VFD) is a new ``green'' approach in the synthesis of organic chemicals with many industrial applications in biodiesel generation, cosmetics, protein folding and pharmaceutical production. The VFD is a rapidly rotating tube that can operate with a jet feeding drops of liquid reactants to the base of the tube. The aim of this project is to explain the fluid mechanics of the VFD that influence the rate of reactions. The reaction rate is intimately related to the intense shearing that promotes collision between reactant molecules. In the VFD, the highest shears are found at the bottom of the tube in the Rayleigh and the Ekman layer and at the walls in the Stewardson layers. As a step towards optimising the performance of the VFD we present experiments conducted in order to establish the minimum drop volume and maximum rotation rate for maximum axisymmetric spreading without fingering instability. PhD candidate, Department of Applied Mathematics and Theoretical Physics.

  16. Supercritical fluid mixing in Diesel Engine Applications

    NASA Astrophysics Data System (ADS)

    Bravo, Luis; Ma, Peter; Kurman, Matthew; Tess, Michael; Ihme, Matthias; Kweon, Chol-Bum

    2014-11-01

    A numerical framework for simulating supercritical fluids mixing with large density ratios is presented in the context of diesel sprays. Accurate modeling of real fluid effects on the fuel air mixture formation process is critical in characterizing engine combustion. Recent work (Dahms, 2013) has suggested that liquid fuel enters the chamber in a transcritical state and rapidly evolves to supercritical regime where the interface transitions from a distinct liquid/gas interface into a continuous turbulent mixing layer. In this work, the Peng Robinson EoS is invoked as the real fluid model due to an acceptable compromise between accuracy and computational tractability. Measurements at supercritical conditions are reported from the Constant Pressure Flow (CPF) chamber facility at the Army Research Laboratory. Mie and Schlieren optical spray diagnostics are utilized to provide time resolved liquid and vapor penetration length measurement. The quantitative comparison presented is discussed. Oak Ridge Associated Universities (ORAU).

  17. The Fluid Mechanics of Fires

    NASA Astrophysics Data System (ADS)

    Baum, Howard

    2005-11-01

    The transport of heat and mass by fire induced flows is discussed with emphasis on the role of fire plumes. The fire plume provides the positive feedback mechanisms that determine the fire strength. It also acts as the pump which mixes the fuel and oxidizer distributes the combustion products in space and time. A brief description of some of the observed properties of isolated fire plumes in the laboratory is followed by a ``kinematic'' representation of plume fluid dynamics. In this model, entrainment is related to the vorticity and heat distributions generated by the fire. The utility of this approach is illustrated by appeal both to experiments on individual laboratory plumes and simulations of mass fires. The interaction of fire plumes with atmospheric winds is illustrated by a smoke dispersion model that couples a simplified description of the stratified atmosphere with a CFD based simulation of the large scale fire induced motions. Fire whirls are a rare but potentially catastrophic phenomenon controlled by the interaction of buoyancy with imposed angular momentum. An ``exact'' solution of the low Mach number combustion equations illustrates the changes induced by rotation. Finally, the simulation fire dynamics in enclosures is illustrated with results from the NIST investigation of the collapse of the World Trade Center towers.

  18. Fluid mechanics of microscale flight

    NASA Astrophysics Data System (ADS)

    Hennighausen, Konstantinos

    2001-12-01

    Recent advancements in nanotechnology, materials, manufacturing, and electronic sensors have raised interest in building increasingly small micro air vehicles (MAVs). These aircraft are presently built and flown with wingspans on the order of ten centimeters. Future MAVs, with wingspans below one centimeter, have wide ranging applications in remote sensing. The aerodynamics of present and future MAVs cannot be analysed using the classical techniques developed for conventional aircraft. Their flight, like that of insects, involves strong viscous and unsteady effects. Computational fluid dynamics (CFD) has become an integral tool in the design of modern aircraft. In this dissertation, CFD tools are created to facilitate the analysis and design of MAVs. After examining the relevant physics and mechanism of microscale flight, a palette of tools is developed. First, two approaches to generating grids around a moving, deforming body are explored. These techniques, utilizing three dimensional Bézier hyperpatches and non-uniform rational B-splines, are applied to prototype MAV shapes. A numerical method is developed to integrate the compressible Navier-Stokes equations on a deforming grid, utilizing upwinded differences and a finite volume approach. These tools are then utilized to design and simulate the flow about a prototype MAV. The resulting flow patterns are examined, and suggest that these tools are appropriate means by which to study microscale flight.

  19. NASA Ames Fluid Mechanics Laboratory research briefs

    NASA Technical Reports Server (NTRS)

    Davis, Sanford (Editor)

    1994-01-01

    The Ames Fluid Mechanics Laboratory research program is presented in a series of research briefs. Nineteen projects covering aeronautical fluid mechanics and related areas are discussed and augmented with the publication and presentation output of the Branch for the period 1990-1993.

  20. Trigger mechanism for engines

    SciTech Connect

    Clark, L.R.

    1989-02-28

    A trigger mechanism is described for a blower-vacuum apparatus having a trigger mounted within a handle and a small engine comprising: a throttle; a ''L'' shaped lever having first and second legs mounted for rotation about an intermediate pivot within the handle when the trigger is depressed, interconnecting the trigger and the throttle, the second leg having first teeth defined therein, the lever further having idle, full throttle and stop positions; a normally raised latch means adapted to be rotated and axially depressed, the latch means having second teeth situated on a cam to engage the first teeth for holding the lever in an intermediate position between the idle and full throttle positions when the latch means is rotated. The latch means further are cam teeth into potential engagement with the lever teeth when the trigger is depressed, lever is biased to the stop position; and idle adjusting means means for intercepting the second leg for preventing the second leg from reaching the stop position when the latch means is raised.

  1. FLUID MECHANICS OF ARTIFICIAL HEART VALVES

    PubMed Central

    Dasi, Lakshmi P; Simon, Helene A; Sucosky, Philippe; Yoganathan, Ajit P

    2009-01-01

    SUMMARY 1. Artificial heart valves have been in use for over five decades to replace diseased heart valves. Since the first heart valve replacement performed with a caged-ball valve, more than 50 valve designs have been developed, differing principally in valve geometry, number of leaflets and material. To date, all artificial heart valves are plagued with complications associated with haemolysis, coagulation for mechanical heart valves and leaflet tearing for tissue-based valve prosthesis. For mechanical heart valves, these complications are believed to be associated with non-physiological blood flow patterns. 2. In the present review, we provide a bird’s-eye view of fluid mechanics for the major artificial heart valve types and highlight how the engineering approach has shaped this rapidly diversifying area of research. 3. Mechanical heart valve designs have evolved significantly, with the most recent designs providing relatively superior haemodynamics with very low aerodynamic resistance. However, high shearing of blood cells and platelets still pose significant design challenges and patients must undergo life-long anticoagulation therapy. Bioprosthetic or tissue valves do not require anticoagulants due to their distinct similarity to the native valve geometry and haemodynamics, but many of these valves fail structurally within the first 10–15 years of implantation. 4. These shortcomings have directed present and future research in three main directions in attempts to design superior artificial valves: (i) engineering living tissue heart valves; (ii) development of advanced computational tools; and (iii) blood experiments to establish the link between flow and blood damage. PMID:19220329

  2. Fluid mechanics in the perivascular space.

    PubMed

    Wang, Peng; Olbricht, William L

    2011-04-07

    Perivascular space (PVS) within the brain is an important pathway for interstitial fluid (ISF) and solute transport. Fluid flowing in the PVS can affect these transport processes and has significant impacts on physiology. In this paper, we carry out a theoretical analysis to investigate the fluid mechanics in the PVS. With certain assumptions and approximations, we are able to find an analytical solution to the problem. We discuss the physical meanings of the solution and particularly examine the consequences of the induced fluid flow in the context of convection-enhanced delivery (CED). We conclude that peristaltic motions of the blood vessel walls can facilitate fluid and solute transport in the PVS.

  3. Instructor's Guide for Fluid Mechanics: A Modular Approach.

    ERIC Educational Resources Information Center

    Cox, John S.

    This guide is designed to assist engineering teachers in developing an understanding of fluid mechanics in their students. The course is designed around a set of nine self-paced learning modules, each of which contains a discussion of the subject matter; incremental objectives; problem index, set and answers; resource materials; and a quiz with…

  4. Diesel Engine Mechanics.

    ERIC Educational Resources Information Center

    Foutes, William A.

    Written in student performance terms, this curriculum guide on diesel engine repair is divided into the following eight sections: an orientation to the occupational field and instructional program; instruction in operating principles; instruction in engine components; instruction in auxiliary systems; instruction in fuel systems; instruction in…

  5. Analysis of Skylab fluid mechanics science demonstrations

    NASA Technical Reports Server (NTRS)

    Tegart, J. R.; Butz, J. R.

    1975-01-01

    The results of the data reduction and analysis of the Skylab fluid mechanics demonstrations are presented. All the fluid mechanics data available from the Skylab missions were identified and surveyed. The significant fluid mechanics phenomena were identified and reduced to measurable quantities wherever possible. Data correlations were performed using existing theories. Among the phenomena analyzed were: static low-g interface shapes, oscillation frequency and damping of a liquid drop, coalescence, rotating drop, liquid films and low-g ice melting. A survey of the possible applications of the results was made and future experiments are recommended.

  6. Statistical mechanics of associating fluids

    NASA Astrophysics Data System (ADS)

    Touba, Hassan

    Two approaches have been considered in the study of thermodynamics of associating fluids. The first approach is related to submitting equations of state based on analytic chain association theory (ACAT). An associating fluid has been assumed to be a mixture of monomer, dimer, trimer, etc., and the composition distribution of the associating species has been obtained. The second view is to develop analytical expressions for the radial distribution functions (RDF). Initially, the molecular structure of simpler fluids is taken into account and an expression for the first shell of the RDF of such fluids is proposed. This expression satisfies all the limiting cases of the hard-sphere RDF at high temperatures, the ideal gas RDF at zero density, and the dilute-gas RDF at low densities. The only requirement is the introduction of a potential function into the model. This theory has been applied to the Lennard-Jones, Kihara and square-well pair intermolecular potential energy functions, and is also tested versus the experimental results for the argon RDF. Good agreement was obtained in most of the cases studied over a broad range of density and temperature. The expression for RDF is then incorporated with an effective Kihara pair potential for water which is a good example of an associating fluid. In this model, the ACAT is applied to the parameters of the potential function. These parameters are obtained in such a way that the experimental first shell RDF data of water can be reproduced at various temperatures. Comparisons of the predicted results for water at sub- and super-critical conditions with the simulation and diffraction data show an overall good agreement. One of the distinct properties of fluids is the molar refraction. It is shown here that the use of molar refraction as a measure of asymmetry of various compounds is inherently simple and yields more precise results than other available methods. The application of molar refraction is discussed for predicting

  7. Importance of mechanical testing of hydraulic fluids

    SciTech Connect

    Reichel, J.

    1997-12-31

    Anti-wear properties of hydraulic fluids are important because hydraulic pump and motor wear is costly. Hydraulic fluid performance specifications represent minimum requirements. International hydraulic fluid performance standards are being developed by ISO/TC28/SC4 committee as draft (ISO DIS 11158 ``Specifications for Mineral Oil Hydraulic Fluids``). Performance specifications for non-mineral oil hydraulic fluids are also being developed. Typically, both the user and fluid manufacturer have insufficient information relating to the anti-wear properties of a new fluid to be used in hydraulic equipment, such as axial piston pumps, vane pumps or radial piston motors. Therefore, pump lubrication and operation requirements, preferably pre-existing in pump manufacturer`s specifications, must be determined. The required fluid lubrication properties may be determined by either laboratory pump tests or by a field trial, often at the expense of the customer. More preferably, the lubrication properties of the hydraulic fluid should be determined under mechanical conditions equivalent to field practice. In this paper, the use of both the vane pump test and the FZG Gear Test to predetermine the recommended hydraulic fluid lubrication performance will be discussed. In this way, fluid performance may be determined at significantly lower cost than more expensive large scale hydraulic pump and motor tests which are slower and more energy consuming.

  8. Fluid Mechanics of Spinning Rockets.

    DTIC Science & Technology

    1987-01-01

    internal energy dissipation is present. A classic case was the instability exhibited by the first American earth satellite, the Explorer I, which...measure the pressure fluctuations. Water was used as the working fluid. This is acceptable in these simulations, since compressibility is not a...nozzle are responsible for the the apparition of the instability late in the motor bum. In conclusion, it has been shown that an unsteady internal gas

  9. The effect of ascorbic acid and fluid flow stimulation on the mechanical properties of a tissue engineered pelvic floor repair material.

    PubMed

    Osman, Nadir I; Roman, Sabiniano; Bullock, Anthony J; Chapple, Christopher R; MacNeil, Sheila

    2014-09-01

    Synthetic non-degradable meshes used in pelvic floor surgery can cause serious complications such as tissue erosion. A repair material composed of an autologous oral fibroblast seeded degradable polylactic acid scaffold may be a viable alternative. The aims of this study were to investigate the effects of media supplementation with additives (ascorbic acid-2-phosphate, glycolic acid and 17-β-oestradiol) on the mechanical properties of these scaffolds. Oral fibroblasts were isolated from buccal mucosa. The effects of the three additives were initially compared in two-dimensional culture to select the most promising collagen stimulating additive. Sterile electrospun scaffolds were seeded with 500,000 oral fibroblasts and fixed in 6-well plates and subjected to ascorbic acid-2-phosphate (the best performing additive) and/or mechanical stimulation. Mechanical stimulation by fluid shear stress was induced by rocking scaffolds on a platform shaker for 1 h/day for 10 of 14 days of culture. In two-dimensional culture, ascorbic acid-2-phosphate (concentrations from 0.02 mM to 0.04 M) and glycolic acid (10 µM) led to significantly greater total collagen production, but ascorbic acid-2-phosphate at 0.03 mM produced the greatest stimulation (of the order of >100%). In three-dimensional culture, mechanical stimulation alone gave non-significant increases in stiffness and strength. Ascorbic acid-2-phosphate (0.03 mM) significantly increased collagen production in the order 280% in both static and mechanically stimulated scaffolds (p < 0.0001). There was no additional effect of mechanical stimulation. Dense collagen I fibres were observed with ascorbic acid-2-phosphate supplementation. Uniaxial tensiometry showed that strength (p < 0.01) and stiffness (p <0.05) both improved significantly. A combination of ascorbic acid-2-phosphate and mechanical stimulation led to further non-signficant increases in strength and stiffness. In conclusion, a pelvic floor

  10. Mechanical Engineering Department Technical Review

    SciTech Connect

    Carr, R.B.; Denney, R.M.

    1981-07-01

    The Mechanical Engineering Department Technical Review is published to inform readers of various technical activities within the Department, promote exchange of ideas, and give credit to personnel who are achieving the results. The report is presented in two parts: technical achievements and publication abstracts. The first is divided into seven sections, each of which reports on an engineering division and its specific activities related to nuclear tests, nuclear explosives, weapons, energy systems, engineering sciences, magnetic fusion, and materials fabrication.

  11. Mechanical Engineering Department technical abstracts

    SciTech Connect

    Not Available

    1984-07-01

    The Mechanical Engineering Department publishes abstracts twice a year to inform readers of the broad range of technical activities in the Department, and to promote an exchange of ideas. Details of the work covered by an abstract may be obtained by contacting the author(s). General information about the current role and activities of each of the Department's seven divisions precedes the technical abstracts. Further information about a division's work may be obtained from the division leader, whose name is given at the end of each divisional summary. The Department's seven divisions are as follows: Nuclear Test Engineering Division, Nuclear Explosives Engineering Division, Weapons Engineering Division, Energy Systems Engineering Division, Engineering Sciences Division, Magnetic Fusion Engineering Division and Materials Fabrication Division.

  12. Some connections between fluid mechanics and the solving of industrial and environmental fluid-flow problems

    NASA Astrophysics Data System (ADS)

    Hunt, J. C. R.

    1981-05-01

    The ways in which advances in fluid mechanics have led to improvements in engineering design are discussed, with attention to the stimulation of fluid mechanics research by industrial and environmental problems. The development of many practical uses of fluid flow without the benefit of scientific study is also emphasized. Among the topics discussed are vortices and coherent structures in turbulent flows, lubrication, jet and multiphase flows, the control and exploitation of waves, the effect of unsteady forces on structures, and dispersion phenomena. Among the practical achievements covered are the use of bluff shields to control separated flow over truck bodies and reduce aerodynamic drag, ink-jet printing, hovercraft stability, fluidized-bed combustion, the fluid/solid instabilities caused by air flow around a computer memory floppy disc, and various wind turbines.

  13. Mechanics of couple-stress fluid coatings

    NASA Technical Reports Server (NTRS)

    Waxman, A. M.

    1982-01-01

    The formal development of a theory of viscoelastic surface fluids with bending resistance - their kinematics, dynamics, and rheology are discussed. It is relevant to the mechanics of fluid drops and jets coated by a thin layer of immiscible fluid with rather general rheology. This approach unifies the hydrodynamics of two-dimensional fluids with the mechanics of an elastic shell in the spirit of a Cosserat continuum. There are three distinct facets to the formulation of surface continuum mechanics. Outlined are the important ideas and results associated with each: the kinematics of evolving surface geometries, the conservation laws governing the mechanics of surface continua, and the rheological equations of state governing the surface stress and moment tensors.

  14. A Course in Fluid Mechanics of Suspensions.

    ERIC Educational Resources Information Center

    Davis, Robert H.

    1989-01-01

    Discusses a course focusing on fluid mechanics and physical chemistry of suspensions. Describes the main themes of the lectures and includes a list of course outlines. Possible textbooks and many journal articles are listed. (YP)

  15. Multimedia Fluid Mechanics - Multilingual Version CD-ROM

    NASA Astrophysics Data System (ADS)

    Homsy, G. M.; Aref, H.; Breuer, K. S.; Hochgreb, S.; Koseff, J. R.; Munson, B. R.; Powell, K. G.; Robertson, C. R.; Thoroddsen, S. T.

    2004-07-01

    This CD-ROM offers an interactive tool for teaching undergraduate fluid mechanics. It features experiments that demonstrate fluid mechanical phenomena, animations of important principles and concepts, virtual laboratories in which students acquire data from the images, interactive computational exercises in which parameters can be varied, and other descriptive and illuminating material on applications. The material may be accessed randomly through a hyperlinked text, a search engine, a video library, and a glossary of terms. The new edition has been thoroughly updated and includes versions in English, Spanish and French.

  16. Fluid control mechanisms in weightlessness

    NASA Technical Reports Server (NTRS)

    Leach, Carolyn S.

    1987-01-01

    Experiments performed on Space Shuttle flights have emphasized study of the earliest effects of the cephalad fluid shift resulting from microgravity. Analysis of one subject's urine collected during flight showed that a sharp increase in antidiuretic hormone occurred within 2 h of launch, followed by an increase in cortisol excretion. Although this subject had symptoms of the space adaptation syndrome (SAS), inflight data from Spacelab missions suggested that these transient changes were not caused by SAS. Unpaired t-tests and Mann-Whitney tests showed that before and after flight, plasma thyroxine and urine osmolality were significantly higher in Shuttle crewmembers who exhibited more severe symptoms of SAS than in asymptomatic crewmembers.

  17. The fluid mechanics of frost heave

    NASA Astrophysics Data System (ADS)

    Rempel, Alan; Wettlaufer, John; Worster, Grae

    2002-11-01

    Frost heave is a process during which the freezing of a water-saturated soil gives rise to the deformation and upward thrust of the ground surface. The phenomenon plays a central role in sculpting the landscape in regions subject to prolonged freezing and it is responsible for damage to engineered structures. Contrary to popular belief, this behavior is completely unrelated to the density difference between ice and water, but instead is driven by intermolecular forces between ice and soil grains. The rate of heave is controlled by the flow of unfrozen water towards solidification fronts, which take the form of lenses that are parallel to isotherms. As such, the phenomenon of frost heave is common to the thermodynamic phase and fluid mechanical behavior of most materials near their freezing temperatures. The process requires that the interface between the lens material (ice), and the porous material in which it sits, is wet by the liquid phase at temperatures below its bulk melting temperature. This behavior is called ``premelting''. We demonstrate the essence of frost heave by examining the conservation conditions over the surface of an ice lens and show how the net effect of the intermolecular forces that promote lens formation and growth can be calculated explicitly. The rate of heave is determined by the water supply through premelted liquid that separates the ice and mineral surfaces --- both as a result of these same intermolecular interactions, and due to the more passive role played by the surface energy of curved interfaces in determining the geometry of the fluid pathways. By examining the physical interactions that take place on these microscopic length-scales we are able to construct predictive models for the initiation and growth of macroscopic ice lenses in consolidated porous media.

  18. Analogy between fluid cavitation and fracture mechanics

    NASA Technical Reports Server (NTRS)

    Hendricks, R. C.; Mullen, R. L.; Braun, M. J.

    1983-01-01

    When the stresses imposed on a fluid are sufficiently large, rupture or cavitation can occur. Such conditions can exist in many two-phase flow applications, such as the choked flows, which can occur in seals and bearings. Nonspherical bubbles with large aspect ratios have been observed in fluids under rapid acceleration and high shear fields. These bubbles are geometrically similar to fracture surface patterns (Griffith crack model) existing in solids. Analogies between crack growth in solid and fluid cavitation are proposed and supported by analysis and observation (photographs). Healing phenomena (void condensation), well accepted in fluid mechanics, have been observed in some polymers and hypothesized in solid mechanics. By drawing on the strengths of the theories of solid mechanics and cavitation, a more complete unified theory can be developed.

  19. Composite mechanics for engine structures

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.

    1989-01-01

    Recent research activities and accomplishments at Lewis Research Center on composite mechanics for engine structures are summarized. The activities focused mainly on developing procedures for the computational simulation of composite intrinsic and structural behavior. The computational simulation encompasses all aspects of composite mechanics, advanced three-dimensional finite-element methods, damage tolerance, composite structural and dynamic response, and structural tailoring and optimization.

  20. Composite mechanics for engine structures

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.

    1987-01-01

    Recent research activities and accomplishments at Lewis Research Center on composite mechanics for engine structures are summarized. The activities focused mainly on developing procedures for the computational simulation of composite intrinsic and structural behavior. The computational simulation encompasses all aspects of composite mechanics, advanced three-dimensional finite-element methods, damage tolerance, composite structural and dynamic response, and structural tailoring and optimization.

  1. Fluid Mechanics of Blood Clot Formation

    NASA Astrophysics Data System (ADS)

    Fogelson, Aaron L.; Neeves, Keith B.

    2015-01-01

    Intravascular blood clots form in an environment in which hydrodynamic forces dominate and in which fluid-mediated transport is the primary means of moving material. The clotting system has evolved to exploit fluid dynamic mechanisms and to overcome fluid dynamic challenges to ensure that clots that preserve vascular integrity can form over the wide range of flow conditions found in the circulation. Fluid-mediated interactions between the many large deformable red blood cells and the few small rigid platelets lead to high platelet concentrations near vessel walls where platelets contribute to clotting. Receptor-ligand pairs with diverse kinetic and mechanical characteristics work synergistically to arrest rapidly flowing cells on an injured vessel. Variations in hydrodynamic stresses switch on and off the function of key clotting polymers. Protein transport to, from, and within a developing clot determines whether and how fast it grows. We review ongoing experimental and modeling research to understand these and related phenomena.

  2. Fluid Mechanics of Blood Clot Formation.

    PubMed

    Fogelson, Aaron L; Neeves, Keith B

    2015-01-01

    Intravascular blood clots form in an environment in which hydrodynamic forces dominate and in which fluid-mediated transport is the primary means of moving material. The clotting system has evolved to exploit fluid dynamic mechanisms and to overcome fluid dynamic challenges to ensure that clots that preserve vascular integrity can form over the wide range of flow conditions found in the circulation. Fluid-mediated interactions between the many large deformable red blood cells and the few small rigid platelets lead to high platelet concentrations near vessel walls where platelets contribute to clotting. Receptor-ligand pairs with diverse kinetic and mechanical characteristics work synergistically to arrest rapidly flowing cells on an injured vessel. Variations in hydrodynamic stresses switch on and off the function of key clotting polymers. Protein transport to, from, and within a developing clot determines whether and how fast it grows. We review ongoing experimental and modeling research to understand these and related phenomena.

  3. Engineering Graphene Mechanical Systems

    DTIC Science & Technology

    2012-07-05

    Mohiuddin, T. M. G.; Morozov, S. V.; Blake, P.; Halsall, M. P.; Ferrari , A. C.; Boukhvalov, D. W.; Katsnelson, M. I.; Geim, A. K.; Novoselov, K. S. Science...22) Bower, A. F. Linear Elastic Material Behavior. In Applied Mechanics of Solids; CRC Press: Boca Raton, FL, 2010; pp 83−86. (23) Gomez -Navarro, C...Phys. Rev. Lett. 2011, 106, 105505. (26) Ferrari , A. C.; Meyer, J. C.; Scardaci, V.; Casiraghi, C.; Lazzeri, M.; Mauri, F.; Piscanec, S.; Jiang, D

  4. Slip mechanisms in complex fluid flows.

    PubMed

    Hatzikiriakos, Savvas G

    2015-10-28

    The classical no-slip boundary condition of fluid mechanics is not always a valid assumption for the flow of several classes of complex fluids including polymer melts, their blends, polymer solutions, microgels, glasses, suspensions and pastes. In fact, it appears that slip effect in these systems is the rule and not the exemption. The occurrence of slip complicates the analysis of rheological data, although it provides new opportunities to understand their behavior in restricted environments delineating additional molecular mechanisms i.e. entropic restrictions due to limitations in the number of molecular conformations. This article discusses these complexities and provides future research opportunities.

  5. Mechanics of coupled granular/fluid flows

    NASA Astrophysics Data System (ADS)

    Vinningland, J.; Toussaint, R.; Johnsen, O.; Flekkoy, E. G.; Maloy, K. J.

    2006-12-01

    We introduce a hybrid numerical model for coupled flow of solid grains and intersticial fluid, which renders for complex hydrodynamic interactions between mobile grains. This model treats the solid phase as discrete particles, interacting mechanically with the other particles and with the intersticial flowing fluid. The fluid is described by continuum equations rendering for its advection by the local grains, superposed to a pressure diffusion ruled by a Darcy flow with a permeability depending on the local solid fraction. This model is aimed at describing accurately such coupled flow. This model is tested for two model situations, where it is compared to experimental results: 1/ Injection of a localized overpressure in a grain/fluid filled cell lying horizontally, where gravity is unimportant. 2/ Sedimentation of heavy grains falling into an initially grain-free fluid region. The development of pattern-forming instabilities is obtained in these two situations, corresponding to granular/fluid equivalents of the two-fluids Saffman-Taylor and Rayleigh-Taylor instabilities. Numerical and experimental results are shown to be consistent with each other.

  6. Bellcrank mechanisms for Stirling engines

    SciTech Connect

    Senft, J.R.; Senft, V.J.

    1996-12-31

    This paper describes a family of linkage drive systems for Stirling engines containing several new members. These mechanisms are adaptable to all three configurations of Stirling engine, impose minimal side loads on pistons and displacer rods, and include compact forms suitable for pressurized high performance engines. This group of drive systems is generated by a simple common scheme. Near sinusoidal motion is taken from a crankshaft carrying a single crankpin by two connecting rods each driving a bellcrank. The stationary pivots of the bellcranks are located so that their oscillatory motion has the phase angle separation required between the piston and displacer. The bellcranks are further configured to bring the third pin motion to a location suitable for coupling with the piston or displacer of the engine in a way which minimizes side loading. The paper presents a number of new linkage drives from the dual bellcrank family and indicates how they are embodied in beta and alpha type Stirling engines. The paper includes a design for a small multipurpose engine incorporating one of the subject mechanisms.

  7. Links between microscopic and macroscopic fluid mechanics

    NASA Astrophysics Data System (ADS)

    Hoover, Wm. G.; Hoover, C. G.

    2003-01-01

    The microscopic and macroscopic versions of fluid mechanics differ qualitatively. Microscopic particles obey time-reversible ordinary differential equations. The resulting particle trajectories {q(t)} may be time-averaged or ensemble-averaged so as to generate field quantities corresponding to macroscopic variables. On the other hand, the macroscopic continuum fields described by fluid mechanics follow irreversible partial differential equations. Smooth particle methods bridge the gap separating these two views of fluids by solving the macroscopic field equations with particle dynamics that resemble molecular dynamics. Recently, nonlinear dynamics have provided some useful tools for understanding the relationship between the microscopic and macroscopic points of view. Chaos and fractals play key roles in this new understanding. Non-equilibrium phase-space averages look very different from their equilibrium counterparts. Away from equilibrium the smooth phase-space distributions are replaced by fractional-dimensional singular distributions that exhibit time irreversibility.

  8. Current research activities: Applied and numerical mathematics, fluid mechanics, experiments in transition and turbulence and aerodynamics, and computer science

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Research conducted at the Institute for Computer Applications in Science and Engineering in applied mathematics, numerical analysis, fluid mechanics including fluid dynamics, acoustics, and combustion, aerodynamics, and computer science during the period 1 Apr. 1992 - 30 Sep. 1992 is summarized.

  9. Thirteenth symposium on energy engineering sciences: Proceedings. Fluid/thermal processes, systems analysis and control

    SciTech Connect

    1995-11-01

    The DOE Office of Basic Energy Sciences, of which Engineering Research is a component program, is responsible for the long-term mission-oriented research in the Department. Consistent with the DOE/BES mission, the Engineering Research Program is charged with the identification, initiation, and management of fundamental research on broad, generic topics addressing energy-related engineering problems. Its stated goals are: (1) to improve and extend the body of knowledge underlying current engineering practice so as to create new options for enhancing energy savings and production, for prolonging useful life of energy-related structures and equipment, and for developing advanced manufacturing technologies and materials processing with emphasis on reducing costs with improved industrial production and performance quality; and (2) to expand the store of fundamental concepts for solving anticipated and unforeseen engineering problems in the energy technologies. The meeting covered the following areas: (1) fluid mechanics 1--fundamental properties; (2) fluid mechanics 2--two phase flow; (3) thermal processes; (4) fluid mechanics 3; (5) process analysis and control; (6) fluid mechanics 4--turbulence; (7) fluid mechanics 5--chaos; (8) materials issues; and (9) plasma processes. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database.

  10. Neural Control Mechanisms and Body Fluid Homeostasis

    NASA Technical Reports Server (NTRS)

    Johnson, Alan Kim

    1998-01-01

    The goal of the proposed research was to study the nature of afferent signals to the brain that reflect the status of body fluid balance and to investigate the central neural mechanisms that process this information for the activation of response systems which restore body fluid homeostasis. That is, in the face of loss of fluids from intracellular or extracellular fluid compartments, animals seek and ingest water and ionic solutions (particularly Na(+) solutions) to restore the intracellular and extracellular spaces. Over recent years, our laboratory has generated a substantial body of information indicating that: (1) a fall in systemic arterial pressure facilitates the ingestion of rehydrating solutions and (2) that the actions of brain amine systems (e.g., norepinephrine; serotonin) are critical for precise correction of fluid losses. Because both acute and chronic dehydration are associated with physiological stresses, such as exercise and sustained exposure to microgravity, the present research will aid in achieving a better understanding of how vital information is handled by the nervous system for maintenance of the body's fluid matrix which is critical for health and well-being.

  11. ADDRESSING ENVIRONMENTAL ENGINEERING CHALLENGES WITH COMPUTATIONAL FLUID DYNAMICS

    EPA Science Inventory

    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 ...

  12. Computational fluid mechanics utilizing the variational principle of modeling damping seals

    NASA Technical Reports Server (NTRS)

    Abernathy, J. M.; Farmer, R.

    1985-01-01

    An analysis for modeling damping seals for use in Space Shuttle main engine turbomachinery is being produced. Development of a computational fluid mechanics code for turbulent, incompressible flow is required.

  13. Computational fluid mechanics utilizing the variational principle of modeling damping seals

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The pressure solution for incompressible flow was investigated in support of a computational fluid mechanics model which simulates the damping seals considered for use in the space shuttle main engine turbomachinery. Future work directions are discussed briefly.

  14. Mechanical design problems associated with turbopump fluid film bearings

    NASA Technical Reports Server (NTRS)

    Evces, Charles R.

    1990-01-01

    Most high speed cryogenic turbopumps for liquid propulsion rocket engines currently use ball or roller contact bearings for rotor support. The operating speeds, loads, clearances, and environments of these pumps combine to make bearing wear a limiting factor on turbopump life. An example is the high pressure oxygen turbopump (HPOTP) used in the Space Shuttle Main Engine (SSME). Although the HPOTP design life is 27,000 seconds at 30,000 rpms, or approximately 50 missions, bearings must currently be replaced after 2 missions. One solution to the bearing wear problem in the HPOTP, as well as in future turbopump designs, is the utilization of fluid film bearings in lieu of continuous contact bearings. Hydrostatic, hydrodynamic, and damping seal bearings are all replacement candidates for contact bearings in rocket engine high speed turbomachinery. These three types of fluid film bearings have different operating characteristics, but they share a common set of mechanical design opportunities and difficulties. Results of research to define some of the mechanical design issues are given. Problems considered include transient strat/stop rub, non-operational rotor support, bearing wear inspection and measurement, and bearing fluid supply route. Emphasis is given to the HPOTP preburner pump (PBP) bearing, but the results are pertinent to high-speed cryogenic turbomachinery in general.

  15. 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.

  16. On Liouville's theorem in fluid mechanics

    NASA Astrophysics Data System (ADS)

    Morrison, P. J.; Bouchet, F.; Thalabard, S.; Zaboronski, O. V.

    2011-11-01

    Since the early work of Burgers it has been known that discretizations of fluid models possess a version of Liouville's theorem on conservation of phase space volume. In fact, spectral representations of two-dimensional turbulence are known to have a detailed version of this theorem. The existence of such Liouville theorems led many (e.g. Burgers, Lee, Kraichnan and Montgomery) to consider various statistical mechanical approaches to turbulence. We show how this theorem arises naturally from the Hamiltonian structure of inviscid fluid equations.

  17. Propulsion Mechanism of Catalytic Microjet Engines

    PubMed Central

    Fomin, Vladimir M.; Hippler, Markus; Magdanz, Veronika; Soler, Lluís; Sanchez, Samuel; Schmidt, Oliver G.

    2014-01-01

    We describe the propulsion mechanism of the catalytic microjet engines that are fabricated using rolled-up nanotech. Microjets have recently shown numerous potential applications in nanorobotics but currently there is a lack of an accurate theoretical model that describes the origin of the motion as well as the mechanism of self-propulsion. The geometric asymmetry of a tubular microjet leads to the development of a capillary force, which tends to propel a bubble toward the larger opening of the tube. Because of this motion in an asymmetric tube, there emerges a momentum transfer to the fluid. In order to compensate this momentum transfer, a jet force acting on the tube occurs. This force, which is counterbalanced by the linear drag force, enables tube velocities of the order of 100 μm/s. This mechanism provides a fundamental explanation for the development of driving forces that are acting on bubbles in tubular microjets. PMID:25177214

  18. Fluid mechanical responses to nutrient depletion in fungi and biofilmsa)

    NASA Astrophysics Data System (ADS)

    Brenner, Michael P.

    2014-10-01

    In both fungi and bacterial biofilms, when nutrients are depleted, the organisms cannot physically migrate to find a new source, but instead must develop adaptations that allow them to survive. This paper reviews our work attempting to discover design principles for these adaptations. We develop fluid mechanical models, and aim to understand whether these suggest organizing principles for the observed morphological diversity. Determining whether a proposed organizing principle explains extant biological designs is fraught with difficulty: simply because a design principle predicts characteristics similar to an organism's morphology could just as well be accidental as revealing. In each of the two sets of examples, we adopt different strategies to develop understanding in spite of this difficulty. Within the fungal phylum Ascomycota, we use the large observed diversity of different morphological solutions to the fundamental fluid mechanical problem to measure how far each solution is from a design optimum, thereby measuring how far the extant designs deviate from the hypothesized optimum. This allows comparing different design principles to each other. For biofilms, we use engineering principles to make qualitative predictions of what types of adaptations might exist given the physicochemical properties of the repertoire of proteins that bacteria can create, and then find evidence for these adaptations in experiments. While on the surface this paper addresses the particular adaptations used by the fungal phylum Ascomycota and bacterial biofilms, we also aim to motivate discussion of different approaches to using design principles, fluid mechanical or otherwise, to rationalize observed engineering solutions in biology.

  19. Mechanical Autonomous Stochastic Heat Engine.

    PubMed

    Serra-Garcia, Marc; Foehr, André; Molerón, Miguel; Lydon, Joseph; Chong, Christopher; Daraio, Chiara

    2016-07-01

    Stochastic heat engines are devices that generate work from random thermal motion using a small number of highly fluctuating degrees of freedom. Proposals for such devices have existed for more than a century and include the Maxwell demon and the Feynman ratchet. Only recently have they been demonstrated experimentally, using, e.g., thermal cycles implemented in optical traps. However, recent experimental demonstrations of classical stochastic heat engines are nonautonomous, since they require an external control system that prescribes a heating and cooling cycle and consume more energy than they produce. We present a heat engine consisting of three coupled mechanical resonators (two ribbons and a cantilever) subject to a stochastic drive. The engine uses geometric nonlinearities in the resonating ribbons to autonomously convert a random excitation into a low-entropy, nonpassive oscillation of the cantilever. The engine presents the anomalous heat transport property of negative thermal conductivity, consisting in the ability to passively transfer energy from a cold reservoir to a hot reservoir.

  20. Mechanical Autonomous Stochastic Heat Engine

    NASA Astrophysics Data System (ADS)

    Serra-Garcia, Marc; Foehr, André; Molerón, Miguel; Lydon, Joseph; Chong, Christopher; Daraio, Chiara

    2016-07-01

    Stochastic heat engines are devices that generate work from random thermal motion using a small number of highly fluctuating degrees of freedom. Proposals for such devices have existed for more than a century and include the Maxwell demon and the Feynman ratchet. Only recently have they been demonstrated experimentally, using, e.g., thermal cycles implemented in optical traps. However, recent experimental demonstrations of classical stochastic heat engines are nonautonomous, since they require an external control system that prescribes a heating and cooling cycle and consume more energy than they produce. We present a heat engine consisting of three coupled mechanical resonators (two ribbons and a cantilever) subject to a stochastic drive. The engine uses geometric nonlinearities in the resonating ribbons to autonomously convert a random excitation into a low-entropy, nonpassive oscillation of the cantilever. The engine presents the anomalous heat transport property of negative thermal conductivity, consisting in the ability to passively transfer energy from a cold reservoir to a hot reservoir.

  1. An integrated introduction to the mechanics of solids and fluids: Continuum mechanics as the first mechanics course

    NASA Astrophysics Data System (ADS)

    Rossmann, Jenn Stroud; Dym, Clive; Bassman, Lori

    2014-11-01

    We have developed an introduction to continuum mechanics for sophomore students without any prior knowledge of mechanics. The essence of continuum mechanics, the internal response of materials to external loading, is often obscured by the complex mathematics of its formulation. By building gradually from one- to two- and three-dimensional formulations, we are able to make the essence of the subject more accessible to undergraduates. From this gradual development of ideas, with many illustrative real-world case studies, students develop both physical intuition for how solids and fluids behave, and the mathematical techniques needed to begin to describe this behavior. At the same time they gain a unique appreciation for the connections between solid and fluid mechanics. It is particularly valuable for students interested in biological applications to appreciate the behavior of engineering materials as a spectrum with Hookean solids at one extreme, and Newtonian fluids at another, with many complex behaviors in between..This approach demonstrates the connections between solid and fluid mechanics, as well as the larger mathematical issues shared by both fields, to students who have not yet taken courses in fluid mechanics and/or strength of materials. The context and foundation provided by this educational strategy are available to students as they continue to study either solid or fluid mechanics, or specialize in the connections themselves by returning to a deeper study of the overarching field of continuum mechanics.

  2. Vortex element methods for fluid dynamic analysis of engineering systems

    NASA Astrophysics Data System (ADS)

    Lewis, Reginald Ivan

    The surface-vorticity method of computational fluid mechanics is described, with an emphasis on turbomachinery applications, in an introduction for engineers. Chapters are devoted to surface singularity modeling; lifting bodies, two-dimensional airfoils, and cascades; mixed-flow and radial cascades; bodies of revolution, ducts, and annuli; ducted propellers and fans; three-dimensional and meridional flows in turbomachines; free vorticity shear layers and inverse methods; vortex dynamics in inviscid flows; the simulation of viscous diffusion in discrete vortex modeling; vortex-cloud modeling by the boundary-integral method; vortex-cloud models for lifting bodies and cascades; and grid systems for vortex dynamics and meridional flows. Diagrams, graphs, and the listings for a set of computer programs are provided.

  3. Mechanical Engineering Department. Technical review

    SciTech Connect

    Simecka, W.B.; Condouris, R.A.; Talaber, C.

    1980-01-01

    The Mechanical Engineering Department Technical Review is published to (1) inform the readers of various technical activities within the Department, (2) promote exchange of ideas, and (3) give credit to the personnel who are achieving the results. The report is formatted into two parts: technical achievements and publication abstracts. The first is divided into eight sections, one for each Division in the Department providing the reader with the names of the personnel and the Division accomplishing the work.

  4. Mechanical Engineering Department technical abstracts

    SciTech Connect

    Denney, R.M.

    1982-07-01

    The Mechanical Engineering Department publishes listings of technical abstracts twice a year to inform readers of the broad range of technical activities in the Department, and to promote an exchange of ideas. Details of the work covered by an abstract may be obtained by contacting the author(s). Overall information about current activities of each of the Department's seven divisions precedes the technical abstracts.

  5. Mechanical engineering department technical review

    SciTech Connect

    Carr, R.B. Denney, R.M.

    1981-01-01

    The Mechanical Engineering Department Technical Review is published to: (1) inform the readers of various technical activities within the department, (2) promote exchange of ideas, and (3) give credit to the personnel who are achieving the results. The report is formatted into two parts: technical acievements and publication abstracts. The first is divided into eight sections, one for each division in the department providing the reader with the names of the personnel and the division accomplishing the work.

  6. Expose Mechanical Engineering Students to Biomechanics Topics

    ERIC Educational Resources Information Center

    Shen, Hui

    2011-01-01

    To adapt the focus of engineering education to emerging new industries and technologies nationwide and in the local area, a biomechanics module has been developed and incorporated into a mechanical engineering technical elective course to expose mechanical engineering students at ONU (Ohio Northern University) to the biomedical engineering topics.…

  7. Standardized Curriculum for Diesel Engine Mechanics.

    ERIC Educational Resources Information Center

    Mississippi State Dept. of Education, Jackson. Office of Vocational, Technical and Adult Education.

    Standardized curricula are provided for two courses for the secondary vocational education program in Mississippi: diesel engine mechanics I and II. The eight units in diesel engine mechanics I are as follows: orientation; shop safety; basic shop tools; fasteners; measurement; engine operating principles; engine components; and basic auxiliary…

  8. Statistical mechanical theory of fluid mixtures

    NASA Astrophysics Data System (ADS)

    Zhao, Yueqiang; Wu, Zhengming; Liu, Weiwei

    2014-01-01

    A general statistical mechanical theory of fluid mixtures (liquid mixtures and gas mixtures) is developed based on the statistical mechanical expression of chemical potential of components in the grand canonical ensemble, which gives some new relationships between thermodynamic quantities (equilibrium ratio Ki, separation factor α and activity coefficient γi) and ensemble average potential energy u for one molecule. The statistical mechanical expressions of separation factor α and activity coefficient γi derived in this work make the fluid phase equilibrium calculations can be performed by molecular simulation simply and efficiently, or by the statistical thermodynamic approach (based on the saturated-vapor pressure of pure substance) that does not need microscopic intermolecular pair potential functions. The physical meaning of activity coefficient γi in the liquid phase is discussed in detail from a viewpoint of molecular thermodynamics. The calculated Vapor-Liquid Equilibrium (VLE) properties of argon-methane, methanol-water and n-hexane-benzene systems by this model fit well with experimental data in references, which indicates that this model is accurate and reliable in the prediction of VLE properties for small, large and strongly associating molecules; furthermore the statistical mechanical expressions of separation factor α and activity coefficient γi have good compatibility with classical thermodynamic equations and quantum mechanical COSMO-SAC approach.

  9. Comparing fluid mechanics models with experimental data.

    PubMed

    Spedding, G R

    2003-09-29

    The art of modelling the physical world lies in the appropriate simplification and abstraction of the complete problem. In fluid mechanics, the Navier-Stokes equations provide a model that is valid under most circumstances germane to animal locomotion, but the complexity of solutions provides strong incentive for the development of further, more simplified practical models. When the flow organizes itself so that all shearing motions are collected into localized patches, then various mathematical vortex models have been very successful in predicting and furthering the physical understanding of many flows, particularly in aerodynamics. Experimental models have the significant added convenience that the fluid mechanics can be generated by a real fluid, not a model, provided the appropriate dimensionless groups have similar values. Then, analogous problems can be encountered in making intelligible but independent descriptions of the experimental results. Finally, model predictions and experimental results may be compared if, and only if, numerical estimates of the likely variations in the tested quantities are provided. Examples from recent experimental measurements of wakes behind a fixed wing and behind a bird in free flight are used to illustrate these principles.

  10. Comparing fluid mechanics models with experimental data.

    PubMed Central

    Spedding, G R

    2003-01-01

    The art of modelling the physical world lies in the appropriate simplification and abstraction of the complete problem. In fluid mechanics, the Navier-Stokes equations provide a model that is valid under most circumstances germane to animal locomotion, but the complexity of solutions provides strong incentive for the development of further, more simplified practical models. When the flow organizes itself so that all shearing motions are collected into localized patches, then various mathematical vortex models have been very successful in predicting and furthering the physical understanding of many flows, particularly in aerodynamics. Experimental models have the significant added convenience that the fluid mechanics can be generated by a real fluid, not a model, provided the appropriate dimensionless groups have similar values. Then, analogous problems can be encountered in making intelligible but independent descriptions of the experimental results. Finally, model predictions and experimental results may be compared if, and only if, numerical estimates of the likely variations in the tested quantities are provided. Examples from recent experimental measurements of wakes behind a fixed wing and behind a bird in free flight are used to illustrate these principles. PMID:14561348

  11. Respiratory fluid mechanics and transport processes.

    PubMed

    Grotberg, J B

    2001-01-01

    The field of respiratory flow and transport has experienced significant research activity over the past several years. Important contributions to the knowledge base come from pulmonary and critical care medicine, surgery, physiology, environmental health sciences, biophysics, and engineering. Several disciplines within engineering have strong and historical ties to respiration including mechanical, chemical, civil/environmental, aerospace and, of course, biomedical engineering. This review draws from a wide variety of scientific literature that reflects the diverse constituency and audience that respiratory science has developed. The subject areas covered include nasal flow and transport, airway gas flow, alternative modes of ventilation, nonrespiratory gas transport, aerosol transport, airway stability, mucus transport, pulmonary acoustics, surfactant dynamics and delivery, and pleural liquid flow. Within each area are a number of subtopics whose exploration can provide the opportunity of both depth and breadth for the interested reader.

  12. SMAP Instrument Mechanical System Engineering

    NASA Technical Reports Server (NTRS)

    Slimko, Eric; French, Richard; Riggs, Benjamin

    2013-01-01

    The Soil Moisture Active Passive (SMAP) mission, scheduled for launch by the end of 2014, is being developed to measure the soil moisture and soil freeze/thaw state on a global scale over a three-year period. The accuracy, resolution, and global coverage of SMAP measurements are invaluable across many science and applications disciplines including hydrology, climate, carbon cycle, and the meteorological, environment, and ecology applications communities. The SMAP observatory is composed of a despun bus and a spinning instrument platform that includes both a deployable 6 meter aperture low structural frequency Astromesh reflector and a spin control system. The instrument section has engendered challenging mechanical system issues associated with the antenna deployment, flexible antenna pointing in the context of a multitude of disturbances, spun section mass properties, spin control system development, and overall integration with the flight system on both mechanical and control system levels. Moreover, the multitude of organizations involved, including two major vendors providing the spin subsystem and reflector boom assembly plus the flight system mechanical and guidance, navigation, and control teams, has led to several unique system engineering challenges. Capturing the key physics associated with the function of the flight system has been challenging due to the many different domains that are applicable. Key interfaces and operational concepts have led to complex negotiations because of the large number of organizations that integrate with the instrument mechanical system. Additionally, the verification and validation concerns associated with the mechanical system have had required far-reaching involvement from both the flight system and other subsystems. The SMAP instrument mechanical systems engineering issues and their solutions are described in this paper.

  13. Mechanical Engineering Department technical review

    SciTech Connect

    Carr, R.B.; Abrahamson, L.; Denney, R.M.; Dubois, B.E

    1982-01-01

    Technical achievements and publication abstracts related to research in the following Divisions of Lawrence Livermore Laboratory are reported in this biannual review: Nuclear Fuel Engineering; Nuclear Explosives Engineering; Weapons Engineering; Energy Systems Engineering; Engineering Sciences; Magnetic Fusion Engineering; and Material Fabrication. (LCL)

  14. Industrial Applications of LES in Mechanical Engineering

    DTIC Science & Technology

    2001-08-01

    UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADP013624 TITLE: Industrial Applications of LES in Mechanical Engineering DISTRIBUTION...compilation report: ADP013620 thru ADP013707 UNCLASSIFIED INDUSTRIAL APPLICATIONS OF LES IN MECHANICAL ENGINEERING CHISACHI KATO Institute of Industrial...Science University of Tokyo, Tokyo, Japan MASAYUKI KAIHO, AKIRA MANABE Mechanical Engineering Research Laboratory Hitachi LTD., Ibaraki, Japan Abstract

  15. Gray's paradox: A fluid mechanical perspective

    PubMed Central

    Bale, Rahul; Hao, Max; Bhalla, Amneet Pal Singh; Patel, Namrata; Patankar, Neelesh A.

    2014-01-01

    Nearly eighty years ago, Gray reported that the drag power experienced by a dolphin was larger than the estimated muscle power – this is termed as Gray's paradox. We provide a fluid mechanical perspective of this paradox. The viewpoint that swimmers necessarily spend muscle energy to overcome drag in the direction of swimming needs revision. For example, in undulatory swimming most of the muscle energy is directly expended to generate lateral undulations of the body, and the drag power is balanced not by the muscle power but by the thrust power. Depending on drag model utilized, the drag power may be greater than muscle power without being paradoxical. PMID:25082341

  16. Art & Science duality in Fluid Mechanics

    NASA Astrophysics Data System (ADS)

    Chomaz, Jean-Marc

    2014-11-01

    The connections between Art & Science is analysed through examples of my research both in Fluid Mechanics and in Art & Science. Working as a member of the artist group Labofactory and collaborating with more than twenty different artists, I have been exploring for more than twenty-four years a path between art and science that mixes both scientific and artistic imaginations. Formulating questions in science is pure imagination and intuition that does not involve only the sensible side of the brain but the sensitive side, which is able to be non incremental, to understand faster and anticipate. Instead of showing scientific proof or technique, it is possible with Art & Science to directly attempt to share this sensitive side. I will show ten recent installations that involve vortex rings, tornado generators, music propagated in shallow layers, wave tanks used as silent soft drums, boundary layer on a rotating sphere to question climate change, plum ever evolving over a nuclear plan in an water tank, a bubbly fountain in microfluidic... Two installations on the thermohaline circulation staged in a stratified tank and on the generation of earthquake are part of the exhibit ``LOST IN FATHOMS'' with the artist Anaïs Tondeur from 17 October until 29 November 2014 at the GV Art gallery, London. These pieces are like writing poems using fluid mechanics and by doing so re-interrogating our scientific practice and the societal role of science. They symmetrize the relation with the public that involve not only ``outreach'' but ``inreach'' or sharing.

  17. Falsification of dark energy by fluid mechanics

    NASA Astrophysics Data System (ADS)

    Gibson, Carl H.

    2011-11-01

    The 2011 Nobel Prize in Physics has been awarded for the discovery from observations of increased supernovae dimness interpreted as distance, so that the Universe expansion rate has changed from a rate decreasing since the big bang to one that is now increasing, driven by anti-gravity forces of a mysterious dark energy material comprising 70% of the Universe mass-energy. Fluid mechanical considerations falsify both the accelerating expansion and dark energy concepts. Kinematic viscosity is neglected in current stan- dard models of self-gravitational structure formation, which rely on cold dark matter CDM condensations and clusterings that are also falsified by fluid mechanics. Weakly collisional CDM particles do not condense but diffuse away. Photon viscosity predicts su- perclustervoid fragmentation early in the plasma epoch and protogalaxies at the end. At the plasma-gas transition, the plasma fragments into Earth-mass gas planets in trillion planet clumps (proto-globular-star-cluster PGCs). The hydrogen planets freeze to form the dark matter of galaxies and merge to form their stars. Dark energy is a systematic dimming error for Supernovae Ia caused by dark matter planets near hot white dwarf stars at the Chandrasekhar carbon limit. Evaporated planet atmospheres may or may not scatter light from the events depending on the line of sight.

  18. Potential fluid mechanic pathways of platelet activation.

    PubMed

    Shadden, Shawn C; Hendabadi, Sahar

    2013-06-01

    Platelet activation is a precursor for blood clotting, which plays leading roles in many vascular complications and causes of death. Platelets can be activated by chemical or mechanical stimuli. Mechanically, platelet activation has been shown to be a function of elevated shear stress and exposure time. These contributions can be combined by considering the cumulative stress or strain on a platelet as it is transported. Here, we develop a framework for computing a hemodynamic-based activation potential that is derived from a Lagrangian integral of strain rate magnitude. We demonstrate that such a measure is generally maximized along, and near to, distinguished material surfaces in the flow. The connections between activation potential and these structures are illustrated through stenotic flow computations. We uncover two distinct structures that may explain observed thrombus formation at the apex and downstream of stenoses. More broadly, these findings suggest fundamental relationships may exist between potential fluid mechanic pathways for mechanical platelet activation and the mechanisms governing their transport.

  19. Fluid mechanics experiments in oscillatory flow. Volume 2: Tabulated data

    NASA Technical Reports Server (NTRS)

    Seume, J.; Friedman, G.; Simon, T. W.

    1992-01-01

    Results of a fluid mechanics measurement program in oscillating flow within a circular duct are presented. The program began with a survey of transition behavior over a range of oscillation frequency and magnitude and continued with a detailed study at a single operating point. Such measurements were made in support of Stirling engine development. Values of three dimensionless parameters, Re sub max, Re sub w, and A sub R, embody the velocity amplitude, frequency of oscillation, and mean fluid displacement of the cycle, respectively. Measurements were first made over a range of these parameters that are representative of the heat exchanger tubes in the heater section of NASA's Stirling cycle Space Power Research Engine (SPRE). Measurements were taken of the axial and radial components of ensemble-averaged velocity and rms velocity fluctuation and the dominant Reynolds shear stress, at various radial positions for each of four axial stations. In each run, transition from laminar to turbulent flow, and its reverse, were identified and sufficient data was gathered to propose the transition mechanism. Volume 2 contains data reduction program listings and tabulated data (including its graphics).

  20. Technical abstracts: Mechanical engineering, 1990

    SciTech Connect

    Broesius, J.Y.

    1991-03-01

    This document is a compilation of the published, unclassified abstracts produced by mechanical engineers at Lawrence Livermore National Laboratory (LLNL) during the calendar year 1990. Many abstracts summarize work completed and published in report form. These are UCRL-JC series documents, which include the full text of articles to be published in journals and of papers to be presented at meetings, and UCID reports, which are informal documents. Not all UCIDs contain abstracts: short summaries were generated when abstracts were not included. Technical Abstracts also provides descriptions of those documents assigned to the UCRL-MI (miscellaneous) category. These are generally viewgraphs or photographs presented at meetings. An author index is provided at the back of this volume for cross referencing.

  1. Liquid rocket engine fluid-cooled combustion chambers

    NASA Technical Reports Server (NTRS)

    1972-01-01

    A monograph on the design and development of fluid cooled combustion chambers for liquid propellant rocket engines is presented. The subjects discussed are (1) regenerative cooling, (2) transpiration cooling, (3) film cooling, (4) structural analysis, (5) chamber reinforcement, and (6) operational problems.

  2. A cyber-physical approach to experimental fluid mechanics

    NASA Astrophysics Data System (ADS)

    Mackowski, Andrew Williams

    This Thesis documents the design, implementation, and use of a novel type of experimental apparatus, termed Cyber-Physical Fluid Dynamics (CPFD). Unlike traditional fluid mechanics experiments, CPFD is a general-purpose technique that allows one to impose arbitrary forces on an object submerged in a fluid. By combining fluid mechanics with robotics, we can perform experiments that would otherwise be incredibly difficult or time-consuming. More generally, CPFD allows a high degree of automation and control of the experimental process, allowing for much more efficient use of experimental facilities. Examples of CPFD's capabilites include imposing a gravitational force in the horizontal direction (allowing a test object to "fall" sideways in a water channel), simulating nonlinear springs for a vibrating fluid-structure system, or allowing a self-propelled body to move forward under its own force. Because experimental parameters (including forces and even the mass of the test object) are defined in software, one can define entire ensembles of experiments to run autonomously. CPFD additionally integrates related systems such as water channel speed control, LDV flow speed measurements, and PIV flowfield measurements. The end result is a general-purpose experimental system that opens the door to a vast array of fluid-structure interaction problems. We begin by describing the design and implementation of CPFD, the heart of which is a high-performance force-feedback control system. Precise measurement of time-varying forces (including removing effects of the test object's inertia) is more critical here than in typical robotic force-feedback applications. CPFD is based on an integration of ideas from control theory, fluid dynamics, computer science, electrical engineering, and solid mechanics. We also describe experiments using the CPFD experimental apparatus to study vortex-induced vibration (VIV) and oscillating-airfoil propulsion. We show how CPFD can be used to simulate

  3. Fluid mechanics of mathematics testing in Texas

    NASA Astrophysics Data System (ADS)

    Marder, Michael

    2010-03-01

    The performance of Texas high school students on mathematics exams is tightly connected to the level of poverty in the school. I will employ the coarse-graining techniques that lead from molecular motions to fluid mechanics in order to find how student scores evolve over time. I will show that the points of divergence between well-off and low-income kids are particularly clear when viewed as streamlines of a flow in the space of grade-level and score. The results can also be cast in the form of a Fokker-Planck equation, which highlights the separate roles of convection and diffusion. I will use the results the assess the plausibility of using charter schools, highly qualified teachers, and accountability systems as primary agents of school reform.

  4. Small Engines and Outboard Marine Mechanics Curriculum.

    ERIC Educational Resources Information Center

    Alaska State Dept. of Education, Juneau. Div. of Adult and Vocational Education.

    This competency-based curriculum guide is a handbook for the development of small engine and outboard marine mechanics programs. Based on a survey of Alaskan small engines and marine mechanics employers, it includes all competencies a student should acquire in such a mechanics program. The handbook stresses the importance of understanding the…

  5. Fluid mechanics experiments in oscillatory flow. Volume 1: Report

    NASA Technical Reports Server (NTRS)

    Seume, J.; Friedman, G.; Simon, T. W.

    1992-01-01

    Results of a fluid mechanics measurement program in oscillating flow within a circular duct are presented. The program began with a survey of transition behavior over a range of oscillation frequency and magnitude and continued with a detailed study at a single operating point. Such measurements were made in support of Stirling engine development. Values of three dimensionless parameters, Re(sub max), Re(sub w), and A(sub R), embody the velocity amplitude, frequency of oscillation and mean fluid displacement of the cycle, respectively. Measurements were first made over a range of these parameters which included operating points of all Stirling engines. Next, a case was studied with values of these parameters that are representative of the heat exchanger tubes in the heater section of NASA's Stirling cycle Space Power Research Engine (SPRE). Measurements were taken of the axial and radial components of ensemble-averaged velocity and rms-velocity fluctuation and the dominant Reynolds shear stress, at various radial positions for each of four axial stations. In each run, transition from laminar to turbulent flow, and its reverse, were identified and sufficient data was gathered to propose the transition mechanism. Models of laminar and turbulent boundary layers were used to process the data into wall coordinates and to evaluate skin friction coefficients. Such data aids in validating computational models and is useful in comparing oscillatory flow characteristics to those of fully-developed steady flow. Data were taken with a contoured entry to each end of the test section and with flush square inlets so that the effects of test section inlet geometry on transition and turbulence are documented. Volume 1 contains the text of the report including figures and supporting appendices. Volume 2 contains data reduction program listings and tabulated data (including its graphical presentation).

  6. Fluid mechanics experiments in oscillatory flow. Volume 1

    SciTech Connect

    Seume, J.; Friedman, G.; Simon, T.W.

    1992-03-01

    Results of a fluid mechanics measurement program is oscillating flow within a circular duct are present. The program began with a survey of transition behavior over a range of oscillation frequency and magnitude and continued with a detailed study at a single operating point. Such measurements were made in support of Stirling engine development. Values of three dimensionless parameters, Re{sub max}, Re{sub W}, and A{sub R}, embody the velocity amplitude, frequency of oscillation and mean fluid displacement of the cycle, respectively. Measurements were first made over a range of these parameters which included operating points of all Stirling engines. Next, a case was studied with values of these parameters that are representative of the heat exchanger tubes in the heater section of NASA`s Stirling cycle Space Power Research Engine (SPRE). Measurements were taken of the axial and radical components of ensemble-averaged velocity and rms-velocity fluctuation and the dominant Reynolds shear stress, at various radial positions for each of four axial stations. In each run, transition from laminar to turbulent flow, and in reverse, were identified and sufficient data was gathered to propose the transition mechanism. Models of laminar and turbulent boundary layers were used to process the data into wall coordinates and to evaluate skin friction coefficients. Such data aids in validating computational models and is useful in comparing oscillatory flow characteristics to those of fully-developed steady flow. Data were taken with a contoured entry to each end of the test section and with flush square inlets so that the effects of test section inlet geometry on transition and turbulence are documented. The following is presented in two-volumes. Volume I contains the text of the report including figures and supporting appendices. Volume II contains data reduction program listings and tabulated data (including its graphical presentation).

  7. Teaching Continuum Mechanics in a Mechanical Engineering Program

    ERIC Educational Resources Information Center

    Liu, Yucheng

    2011-01-01

    This paper introduces a graduate course, continuum mechanics, which is designed for and taught to graduate students in a Mechanical Engineering (ME) program. The significance of continuum mechanics in engineering education is demonstrated and the course structure is described. Methods used in teaching this course such as topics, class…

  8. Fluid mechanics aspects of magnetic drug targeting.

    PubMed

    Odenbach, Stefan

    2015-10-01

    Experiments and numerical simulations using a flow phantom for magnetic drug targeting have been undertaken. The flow phantom is a half y-branched tube configuration where the main tube represents an artery from which a tumour-supplying artery, which is simulated by the side branch of the flow phantom, branches off. In the experiments a quantification of the amount of magnetic particles targeted towards the branch by a magnetic field applied via a permanent magnet is achieved by impedance measurement using sensor coils. Measuring the targeting efficiency, i.e. the relative amount of particles targeted to the side branch, for different field configurations one obtains targeting maps which combine the targeting efficiency with the magnetic force densities in characteristic points in the flow phantom. It could be shown that targeting efficiency depends strongly on the magnetic field configuration. A corresponding numerical model has been set up, which allows the simulation of targeting efficiency for variable field configuration. With this simulation good agreement of targeting efficiency with experimental data has been found. Thus, the basis has been laid for future calculations of optimal field configurations in clinical applications of magnetic drug targeting. Moreover, the numerical model allows the variation of additional parameters of the drug targeting process and thus an estimation of the influence, e.g. of the fluid properties on the targeting efficiency. Corresponding calculations have shown that the non-Newtonian behaviour of the fluid will significantly influence the targeting process, an aspect which has to be taken into account, especially recalling the fact that the viscosity of magnetic suspensions depends strongly on the magnetic field strength and the mechanical load.

  9. The Status of Fluid Mechanics in Bioengineering Curricula.

    ERIC Educational Resources Information Center

    Miller, Gerald E.; Hyman, William A.

    1981-01-01

    Describes the status of fluid mechanics courses in bioengineering curricula. A survey of institutions offering bioengineering degrees indicates that over half do not require fluid mechanics courses. Suggests increasing number of mechanics courses to increase the quality of bioengineering students and to prepare students for graduate work and more…

  10. Fluid Mechanics of Cricket and Tennis Balls

    NASA Astrophysics Data System (ADS)

    Mehta, Rabindra D.

    2009-11-01

    Aerodynamics plays a prominent role in defining the flight of a ball that is struck or thrown through the air in almost all ball sports. The main interest is in the fact that the ball can often deviate from its initial straight path, resulting in a curved, or sometimes an unpredictable, flight path. It is particularly fascinating that that not all the parameters that affect the flight of a ball are always under human influence. Lateral deflection in flight, commonly known as swing, swerve or curve, is well recognized in cricket and tennis. In tennis, the lateral deflection is produced by spinning the ball about an axis perpendicular to the line of flight, which gives rise to what is commonly known as the Magnus effect. It is now well recognized that the aerodynamics of sports balls are strongly dependent on the detailed development and behavior of the boundary layer on the ball's surface. A side force, which makes a ball curve through the air, can also be generated in the absence of the Magnus effect. In one of the cricket deliveries, the ball is released with the seam angled, which trips the laminar boundary layer into a turbulent state on that side. The turbulent boundary layer separates relatively late compared to the laminar layer on the other side, thereby creating a pressure difference and hence side force. The fluid mechanics of a cricket ball become very interesting at the higher Reynolds numbers and this will be discussed in detail. Of all the round sports balls, a tennis ball has the highest drag coefficient. This will be explained in terms of the contribution of the ``fuzz" drag and how that changes with Reynolds number and ball surface wear. It is particularly fascinating that, purely through historical accidents, small disturbances on the ball surface, such as the stitching on cricket balls and the felt cover on tennis balls are all about the right size to affect boundary layer transition and development in the Reynolds numbers of interest. The fluid

  11. Circulating fluid bed technology within Combustion Engineering Inc.

    SciTech Connect

    Treff, P.J.; Maitland, J.E.

    1995-12-31

    As the worldwide trend for more flexible, cost-effective CFB technology continues as an alternative to pulverized coal and combined cycle steam generation, Combustion Engineering Inc. has drawn on original scientific work and the operating history of numerous BFBs and CFBs worldwide as reported in publicly available literature to introduce many product enhancements for its next generation of circulating fluid bed boilers. The issues of in-furnace surface versus external fluid bed heat exchanger applicability, cyclone and loop seal design, refractory system design and operating requirements, and the suitability of regenerative air heaters for CFB applications will be among the topics discussed in this paper as Combustion Engineering Inc. answers the challenge to continuously advance CFB steam generation.

  12. Application of wave mechanics theory to fluid dynamics problems: Fundamentals

    NASA Technical Reports Server (NTRS)

    Krzywoblocki, M. Z. V.

    1974-01-01

    The application of the basic formalistic elements of wave mechanics theory is discussed. The theory is used to describe the physical phenomena on the microscopic level, the fluid dynamics of gases and liquids, and the analysis of physical phenomena on the macroscopic (visually observable) level. The practical advantages of relating the two fields of wave mechanics and fluid mechanics through the use of the Schroedinger equation constitute the approach to this relationship. Some of the subjects include: (1) fundamental aspects of wave mechanics theory, (2) laminarity of flow, (3) velocity potential, (4) disturbances in fluids, (5) introductory elements of the bifurcation theory, and (6) physiological aspects in fluid dynamics.

  13. Gasoline Engine Mechanics. Florida Vocational Program Guide.

    ERIC Educational Resources Information Center

    University of South Florida, Tampa. Dept. of Adult and Vocational Education.

    This vocational program guide is intended to assist in the organization, operation, and evaluation of a program in gasoline engine mechanics in school districts, area vocational centers, and community colleges. The following topics are covered: job duties of small-engine mechanics; program content (curriculum framework and student performance…

  14. Standardized Curriculum for Outboard Marine Engine Mechanics.

    ERIC Educational Resources Information Center

    Mississippi State Dept. of Education, Jackson. Office of Vocational, Technical and Adult Education.

    This curriculum guide for outboard marine engine mechanics was developed by the state of Mississippi to standardize vocational education course titles and core contents. The objectives contained in this document are common to all outboard marine engine mechanics programs in the state. The guide contains objectives for outboard marine engine…

  15. Magnetic Fluid Gyro Bearing and Caging Mechanism.

    DTIC Science & Technology

    In accordance wtih this invention, a gyro is provided which has a bearing means between the rotor and stator provided by magnetic fluid and a caging...means which also includes a magnetic fluid provided between the rotor and caging plate. The gyro of this invention includes a stator with motor...and mounted about the circumference of the rotor with magnetic fluid between the rotor and stator spherical surfaces and being held by the permanent

  16. Collective fluid mechanics of honeybee nest ventilation

    NASA Astrophysics Data System (ADS)

    Gravish, Nick; Combes, Stacey; Wood, Robert J.; Peters, Jacob

    2014-11-01

    Honeybees thermoregulate their brood in the warm summer months by collectively fanning their wings and creating air flow through the nest. During nest ventilation workers flap their wings in close proximity in which wings continuously operate in unsteady oncoming flows (i.e. the wake of neighboring worker bees) and near the ground. The fluid mechanics of this collective aerodynamic phenomena are unstudied and may play an important role in the physiology of colony life. We have performed field and laboratory observations of the nest ventilation wing kinematics and air flow generated by individuals and groups of honeybee workers. Inspired from these field observations we describe here a robotic model system to study collective flapping wing aerodynamics. We microfabricate arrays of 1.4 cm long flapping wings and observe the air flow generated by arrays of two or more fanning robotic wings. We vary phase, frequency, and separation distance among wings and find that net output flow is enhanced when wings operate at the appropriate phase-distance relationship to catch shed vortices from neighboring wings. These results suggest that by varying position within the fanning array honeybee workers may benefit from collective aerodynamic interactions during nest ventilation.

  17. Fluid mechanical model of the Helmholtz resonator

    NASA Technical Reports Server (NTRS)

    Hersh, A. S.; Walker, B.

    1977-01-01

    A semi-empirical fluid mechanical model of the acoustic behavior of Helmholtz resonators is presented which predicts impedance as a function of the amplitude and frequency of the incident sound pressure field and resonator geometry. The model assumes that the particle velocity approaches the orifice in a spherical manner. The incident and cavity sound fields are connected by solving the governing oscillating mass and momentum conservation equations. The model is in agreement with the Rayleigh slug-mass model at low values of incident sound pressure level. At high values, resistance is predicted to be independent of frequency, proportional to the square root of the amplitude of the incident sound pressure field, and virtually independent of resonator geometry. Reactance is predicted to depend in a very complicated way upon resonator geometry, incident sound pressure level, and frequency. Nondimensional parameters are defined that divide resonator impedance into three categories corresponding to low, moderately low, and intense incident sound pressure amplitudes. The two-microphone method was used to measure the impedance of a variety of resonators. The data were used to refine and verify the model.

  18. Falsification of Dark Energy by Fluid Mechanics

    NASA Astrophysics Data System (ADS)

    Gibson, Carl H.

    2012-03-01

    The 2011 Nobel Prize in Physics was awarded for the discovery of accelerating super- novae dimness, suggesting a remarkable reversal in the expansion rate of the Universe from a decrease to an increase, driven by anti-gravity forces of a mysterious dark energy material comprising 70% of the Universe mass-energy. Fluid mechanics and Herschel- Planck-Spitzer-Hubble etc. space telescope observations falsify both the accelerating ex- pansion rate and dark energy concepts. Kinematic viscosity is neglected in models of self-gravitational structure formation. Large plasma photon viscosity predicts protosu- perclustervoid fragmentation early in the plasma epoch and protogalaxies at the end. At the plasma-gas transition, the gas protogalaxies fragment into Earth-mass rogue plan- ets in highly persistent, trillion-planet clumps (proto-globular-star-cluster PGCs). PGC planets freeze to form the dark matter of galaxies and merge to form their stars, giving the hydrogen triple-point (14 K) infrared emissions observed. Dark energy is a system- atic dimming error for Supernovae Ia caused by partially evaporated planets feeding hot white dwarf stars at the Chandrasekhar carbon limit. Planet atmospheres may or may not dim light from SNe-Ia events depending on the line of sight.

  19. Entropic Lattice Boltzmann Methods for Fluid Mechanics

    NASA Astrophysics Data System (ADS)

    Chikatamarla, Shyam; Boesch, Fabian; Sichau, David; Karlin, Ilya

    2013-11-01

    With its roots in statistical mechanics and kinetic theory, the lattice Boltzmann method (LBM) is a paradigm-changing innovation, offering for the first time an intrinsically parallel CFD algorithm. Over the past two decades, LBM has achieved numerous results in the field of CFD and is now in a position to challenge state-of-the art CFD techniques. Our major restyling of LBM resulted in an unconditionally stable entropic LBM which restored Second Law (Boltzmann H theorem) in the LBM kinetics and thus enabled affordable direct simulations of fluid turbulence. We review here recent advances in ELBM as a practical, modeling-free tool for simulation of turbulent flows in complex geometries. We shall present recent simulations including turbulent channel flow, flow past a circular cylinder, knotted vortex tubes, and flow past a surface mounted cube. ELBM listed all admissible lattices supporting a discrete entropy function and has classified them in hierarchically increasing order of accuracy. Applications of these higher-order lattices to simulations of turbulence and thermal flows shall also be presented. This work was supported CSCS grant s437.

  20. Analogies between continuum dislocation theory, continuum mechanics and fluid mechanics

    NASA Astrophysics Data System (ADS)

    Silbermann, C. B.; Ihlemann, J.

    2017-03-01

    Continuum Dislocation Theory (CDT) relates gradients of plastic deformation in crystals with the presence of geometrically necessary dislocations. Interestingly, CDT shows striking analogies to other branches of continuum mechanics. The present contribution demonstrates this on two essential kinematical quantities which reflect tensorial dislocation properties: the (resultant) Burgers vector and the dislocation density tensor. First, the limiting process for the (resultant) Burgers vector from an integral to a local quantity is performed analogously to the limiting process from the force vector to the traction vector. By evaluating the balance of forces on a tetrahedral volume element, Cauchy found his famous formula relating traction vector and stress tensor. It is shown how this procedure may be adopted to a continuously dislocated tetrahedron. Here, the conservation of Burger’s vector implicates the introduction of the dislocation density tensor. Second, analogies between the plastic flow of a continuously dislocated solid and the liquid flow of a fluid are highlighted: the resultant Burgers vector of a dislocation ensemble plays a similar role as the (resultant) circulation of a vortex tube. Moreover, both vortices within flowing fluids and dislocations within deforming solids induce discontinuities in the velocity field and the plastic distortion field, respectively. Beyond the analogies, some peculiar properties of the dislocation density tensor are presented as well.

  1. Mod I automotive Stirling engine mechanical development

    SciTech Connect

    Simetkosky, M.

    1984-01-01

    The Mod I Stirling engine was the first automotive Stirling engine designed specifically for automotive application. Testing of these engines has revealed several deficiencies in engine mechanical integrity which have been corrected by redesign or upgrade. The main deficiencies uncovered during the Mod I program lie in the combustion, auxiliary, main seal, and heater head areas. This paper will address each of the major area deficiencies in detail, and describe the corrective actions taken as they apply to the Mod I and the next Stirling-engine design, the Upgraded Mod I (a redesign to incorporate new materials for cost/weight reduction and improved performance).

  2. Gelled Complex Fluids: Combining Unique Structures with Mechanical Stability.

    PubMed

    Stubenrauch, Cosima; Gießelmann, Frank

    2016-03-01

    Gelled complex fluids are soft materials in which the microstructure of the complex fluid is combined with the mechanical stability of a gel. To obtain a gelled complex fluid one either adds a gelator to a complex fluid or replaces the solvent in a gel by a complex fluid. The most prominent example of a "natural" gelled complex fluid is the cell. There are various strategies by which one can form a gelled complex fluid; one such strategy is orthogonal self-assembly, that is, the independent but simultaneous formation of two coexisting self-assembled structures within one system. The aim of this Review is to describe the structure and potential applications of various man-made gelled complex fluids and to clarify whether or not the respective system is formed by orthogonal self-assembly.

  3. Quantitative image processing in fluid mechanics

    NASA Technical Reports Server (NTRS)

    Hesselink, Lambertus; Helman, James; Ning, Paul

    1992-01-01

    The current status of digital image processing in fluid flow research is reviewed. In particular, attention is given to a comprehensive approach to the extraction of quantitative data from multivariate databases and examples of recent developments. The discussion covers numerical simulations and experiments, data processing, generation and dissemination of knowledge, traditional image processing, hybrid processing, fluid flow vector field topology, and isosurface analysis using Marching Cubes.

  4. Engineering Change Management Method Framework in Mechanical Engineering

    NASA Astrophysics Data System (ADS)

    Stekolschik, Alexander

    2016-11-01

    Engineering changes make an impact on different process chains in and outside the company, and lead to most error costs and time shifts. In fact, 30 to 50 per cent of development costs result from technical changes. Controlling engineering change processes can help us to avoid errors and risks, and contribute to cost optimization and a shorter time to market. This paper presents a method framework for controlling engineering changes at mechanical engineering companies. The developed classification of engineering changes and accordingly process requirements build the basis for the method framework. The developed method framework comprises two main areas: special data objects managed in different engineering IT tools and process framework. Objects from both areas are building blocks that can be selected to the overall business process based on the engineering process type and change classification. The process framework contains steps for the creation of change objects (both for overall change and for parts), change implementation, and release. Companies can select singleprocess building blocks from the framework, depending on the product development process and change impact. The developed change framework has been implemented at a division (10,000 employees) of a big German mechanical engineering company.

  5. Bone tissue engineering: the role of interstitial fluid flow

    NASA Technical Reports Server (NTRS)

    Hillsley, M. V.; Frangos, J. A.

    1994-01-01

    It is well established that vascularization is required for effective bone healing. This implies that blood flow and interstitial fluid (ISF) flow are required for healing and maintenance of bone. The fact that changes in bone blood flow and ISF flow are associated with changes in bone remodeling and formation support this theory. ISF flow in bone results from transcortical pressure gradients produced by vascular and hydrostatic pressure, and mechanical loading. Conditions observed to alter flow rates include increases in venous pressure in hypertension, fluid shifts occurring in bedrest and microgravity, increases in vascularization during the injury-healing response, and mechanical compression and bending of bone during exercise. These conditions also induce changes in bone remodeling. Previously, we hypothesized that interstitial fluid flow in bone, and in particular fluid shear stress, serves to mediate signal transduction in mechanical loading- and injury-induced remodeling. In addition, we proposed that a lack or decrease of ISF flow results in the bone loss observed in disuse and microgravity. The purpose of this article is to review ISF flow in bone and its role in osteogenesis.

  6. Application of the principle of similarity fluid mechanics

    NASA Technical Reports Server (NTRS)

    Hendricks, R. C.; Sengers, J. V.

    1979-01-01

    Possible applications of the principle of similarity to fluid mechanics is described and illustrated. In correlating thermophysical properties of fluids, the similarity principle transcends the traditional corresponding states principle. In fluid mechanics the similarity principle is useful in correlating flow processes that can be modeled adequately with one independent variable (i.e., one-dimensional flows). In this paper we explore the concept of transforming the conservation equations by combining similarity principles for thermophysical properties with those for fluid flow. We illustrate the usefulness of the procedure by applying such a transformation to calculate two phase critical mass flow through a nozzle.

  7. Mechanobiology and the microcirculation: cellular, nuclear and fluid mechanics.

    PubMed

    Dahl, Kris Noel; Kalinowski, Agnieszka; Pekkan, Kerem

    2010-04-01

    Endothelial cells are stimulated by shear stress throughout the vasculature and respond with changes in gene expression and by morphological reorganization. Mechanical sensors of the cell are varied and include cell surface sensors that activate intracellular chemical signaling pathways. Here, possible mechanical sensors of the cell including reorganization of the cytoskeleton and the nucleus are discussed in relation to shear flow. A mutation in the nuclear structural protein lamin A, related to Hutchinson-Gilford progeria syndrome, is reviewed specifically as the mutation results in altered nuclear structure and stiffer nuclei; animal models also suggest significantly altered vascular structure. Nuclear and cellular deformation of endothelial cells in response to shear stress provides partial understanding of possible mechanical regulation in the microcirculation. Increasing sophistication of fluid flow simulations inside the vessel is also an emerging area relevant to the microcirculation as visualization in situ is difficult. This integrated approach to study--including medicine, molecular and cell biology, biophysics and engineering--provides a unique understanding of multi-scale interactions in the microcirculation.

  8. Taking Fluid Mechanics to the General Public

    NASA Astrophysics Data System (ADS)

    Guyon, Etienne; Guyon, Marie Yvonne

    2014-01-01

    Fluid flow phenomena are omnipresent; they can be observed and described in many locations and circumstances. However, in most cases, their presence does not stimulate an interest in science. We consider successively domains of activities in which the presence of fluid flow phenomena can be used: natural sites, industrial ones, sporting events, artistic creations and presentations, the production of images and books, science museums, cultural centers, and also popular mass media. The last section is devoted to outreach activities that can be practiced within the educational system.

  9. Diffuse-Interface Methods in Fluid Mechanics

    NASA Technical Reports Server (NTRS)

    Anderson, D. M.; McFadden, G. B.; Wheeler, A. A.

    1997-01-01

    The authors review the development of diffuse-interface models of hydrodynamics and their application to a wide variety of interfacial phenomena. The authors discuss the issues involved in formulating diffuse-interface models for single-component and binary fluids. Recent applications and computations using these models are discussed in each case. Further, the authors address issues including sharp-interface analyses that relate these models to the classical free-boundary problem, related computational approaches to describe interfacial phenomena, and related approaches describing fully-miscible fluids.

  10. The Role of CFD in Undergraduate Fluid Mechanics Education

    NASA Astrophysics Data System (ADS)

    Cimbala, John

    2006-11-01

    Instruction of undergraduate fluid mechanics is greatly enhanced through integration of computational fluid dynamics (CFD) into fluid mechanics courses and labs. Specifically, students are able to visualize fluid flows with CFD and are better able to understand those flows by performing parametric studies. At Penn State, CFD has been carefully integrated into our introductory junior-level fluid mechanics course, yet displaces only about one class period. The key is to show demonstrations and assign homework that use CFD as a tool that helps students learn the basic concepts of fluid mechanics. The application of CFD (grid generation, boundary conditions, etc.), rather than numerical algorithms, is stressed. This is done through use of short, pre-defined templates for FlowLab, a student-friendly analysis and visualization package created by Fluent, Inc. The textbook by Cengel and Cimbala (McGraw-Hill 2006) contains 46 end-of-chapter homework problems that are used in conjunction with 42 FlowLab templates. Each exercise has been designed with two major learning objectives in mind: (1) enhance student understanding of a specific fluid mechanics concept, and (2) introduce the student to a specific capability and/or limitation of CFD through hands-on practice. More templates are being developed that emphasize the first objective. The flow of fluid between two concentric rotating cylinders is a good example of a problem that is solved approximately, analytically, and with CFD, and the results are compared to enhance learning.

  11. Bernoulli and Newton in Fluid Mechanics

    ERIC Educational Resources Information Center

    Smith, Norman F.

    1972-01-01

    Bernoulli's theorem can be better understood with the aid of Newton's laws and the law of conservation of energy. Application of this theorem should involve only cases dealing with an interchange of velocity and pressure within a fluid under isentropic conditions. (DF)

  12. Fluid Mechanics in the Subtectorial Space

    NASA Astrophysics Data System (ADS)

    Baumgart, J.; Chiaradia, C.; Fleischer, M.; Yarin, Y.; Grundmann, R.; Gummer, A. W.

    2009-02-01

    In the subtectorial space, momentum is transported by the fluid to the stereocilia of the inner hair cell (IHC), resulting in bending of the hair bundle. The fluid must pass through the v-shaped arrangement of the outer hair cell (OHC) stereocilia and is "squeezed" between the tectorial membrane (TM) and the reticular lamina, especially due to the Hensen's stripe. Here, we analyze the flow field by means of numerical discretization. Since the geometry is complex, the finite-element-method is employed. An implementation is developed which allows computation in the frequency domain, based on a pressure stabilised velocity formulation. Matrix coupling with the structure is accomplished and a single solution step of the whole system matrix is sufficient to retrieve the displacement field of the fluid and structural parts. The proposed method allows a solution of the fluid-structure interaction in the subtectorial space within a reasonable time. For a two-dimensional mesh with 120,000 degrees of freedom of a complete cross-section of the organ of Corti, including stereocilia, the solution time is less than 20 seconds on a convential PC.

  13. Engineering mechanics: statics and dynamics. [Textbook

    SciTech Connect

    Sandor, B.I.

    1983-01-01

    The purpose of this textbook is to provide engineering students with basic learning material about statics and dynamics which are fundamental engineering subjects. The chapters contain information on: an introduction to engineering mechanics; forces on particles, rigid bodies, and structures; kinetics of particles, particle systems, and rigid bodies in motion; kinematics; mechanical vibrations; and friction, work, moments of inertia, and potential energy. Each chapter contains introductory material, the development of the essential equations, worked-out example problems, homework problems, and, finally, summaries of the essential methods and equations, graphically illustrated where appropriate. (LCL)

  14. Analysis of fluid/mechanical systems using EASY5

    NASA Technical Reports Server (NTRS)

    Clark, Robert W., Jr.; Arndt, Scott D.; Hurlbert, Eric A.

    1992-01-01

    This paper illustrates how the use of a general analysis package can simplify modeling and analyzing fluid/mechanical systems. One such package is EASY5, a Boeing Computer Services product. The basic transmission line equations for modeling piped fluid systems are presented, as well as methods of incorporating these equations into the EASY5 environment. The paper describes how this analysis tool has been used to model several fluid subsystems of the Space Shuttle Orbiter.

  15. Application of the principle of similarity fluid mechanics

    NASA Technical Reports Server (NTRS)

    Hendericks, R. C.; Sengers, J. V.

    1979-01-01

    The principle of similarity applied to fluid mechanics is described and illustrated. The concept of transforming the conservation equations by combining similarity principles for thermophysical properties with those for fluid flow is examined. The usefulness of the procedure is illustrated by applying such a transformation to calculate two phase critical mass flow through a nozzle.

  16. Fluid Mechanics, Arterial Disease, and Gene Expression

    PubMed Central

    Tarbell, John M.; Shi, Zhong-Dong; Dunn, Jessilyn; Jo, Hanjoong

    2014-01-01

    This review places modern research developments in vascular mechanobiology in the context of hemodynamic phenomena in the cardiovascular system and the discrete localization of vascular disease. The modern origins of this field are traced, beginning in the 1960s when associations between flow characteristics, particularly blood flow–induced wall shear stress, and the localization of atherosclerotic plaques were uncovered, and continuing to fluid shear stress effects on the vascular lining endothelial) cells (ECs), including their effects on EC morphology, biochemical production, and gene expression. The earliest single-gene studies and genome-wide analyses are considered. The final section moves from the ECs lining the vessel wall to the smooth muscle cells and fibroblasts within the wall that are fluid me chanically activated by interstitial flow that imposes shear stresses on their surfaces comparable with those of flowing blood on EC surfaces. Interstitial flow stimulates biochemical production and gene expression, much like blood flow on ECs. PMID:25360054

  17. Fluid Mechanics, Arterial Disease, and Gene Expression.

    PubMed

    Tarbell, John M; Shi, Zhong-Dong; Dunn, Jessilyn; Jo, Hanjoong

    2014-01-01

    This review places modern research developments in vascular mechanobiology in the context of hemodynamic phenomena in the cardiovascular system and the discrete localization of vascular disease. The modern origins of this field are traced, beginning in the 1960s when associations between flow characteristics, particularly blood flow-induced wall shear stress, and the localization of atherosclerotic plaques were uncovered, and continuing to fluid shear stress effects on the vascular lining endothelial) cells (ECs), including their effects on EC morphology, biochemical production, and gene expression. The earliest single-gene studies and genome-wide analyses are considered. The final section moves from the ECs lining the vessel wall to the smooth muscle cells and fibroblasts within the wall that are fluid me chanically activated by interstitial flow that imposes shear stresses on their surfaces comparable with those of flowing blood on EC surfaces. Interstitial flow stimulates biochemical production and gene expression, much like blood flow on ECs.

  18. SIGNAL FLOW GRAPH ANALYSIS OF MECHANICAL ENGINEERING SYSTEMS

    DTIC Science & Technology

    CONTROL SYSTEMS, *MECHANICS, *STRUCTURES, *THERMODYNAMICS, *TOPOLOGY, BEAMS(ELECTROMAGNETIC), BEAMS(STRUCTURAL), GAS FLOW, GEARS, HEAT EXCHANGERS, MATHEMATICAL ANALYSIS, MATHEMATICS, MECHANICAL ENGINEERING , RAMJET ENGINES.

  19. Mechanical engineering aspects of TFTR

    SciTech Connect

    Citrolo, J.C.

    1983-04-01

    This paper briefly presents the principles which characterize a tokamak and discusses the mechanical aspects of TFTR, particularly the toroidal field coils and the vacuum chamber, in the context of being key components common to all tokamaks. The mechanical loads on these items as well as other design requirements are considered and the solutions to these requirements as executed in TFTR are presented. Future technological developments beyond the scope of TFTR, which are necessary to bring the tokamak concept to a full fusion-power system, are also presented. Additional methods of plasma heating, current drive, and first wall designs are examples of items in this category.

  20. Research in progress in applied mathematics, numerical analysis, fluid mechanics, and computer science

    NASA Technical Reports Server (NTRS)

    1994-01-01

    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, 1993 through March 31, 1994. The major categories of the current ICASE research program are: (1) applied and numerical mathematics, including numerical analysis and algorithm development; (2) theoretical and computational research in fluid mechanics in selected areas of interest to LaRC, including acoustics and combustion; (3) experimental research in transition and turbulence and aerodynamics involving LaRC facilities and scientists; and (4) computer science.

  1. Statistical mechanics of simple fluids - Beyond van der Waals

    NASA Astrophysics Data System (ADS)

    Lebowitz, J. L.; Waisman, E. M.

    1980-03-01

    Consideration is given to recent developments in the theory of dense fluids, based on a model fluid of hard spheres. The fluid is treated as consisting of electrically neutral particles interacting through pair potentials dependent only on the distance between their centers, a macroscopic system which can be described by classical statistical mechanics. The van der Waals equation of state and the Maxwell amendment to it for temperatures less than the critical temperature are reviewed, and subsequent rigorous derivations of the amended equation are presented. A relatively simple scheme for approximating a dense, single-component simple classical fluid whose atoms interact via the Lennard-Jones potential, based on the hard sphere model and employing computer calculations is then outlined. It is noted that the approach can be easily generalized to treat quantitatively mixtures of simple fluids, and nonuniform fluids qualitatively, and that there remains much to be done to understand why the schemes presented work as well as they do.

  2. Zero-G fluid mechanics in animal and man

    NASA Technical Reports Server (NTRS)

    Sandler, H.

    1986-01-01

    Significant cardiovascular change occurs with spaceflight. Loss of normal hydrostatic pressure gradients (head-to-foot), present while upright on earth, results in significant headward fluid shift of vascular and interstitial fluids. The resultant fluid change also shifts the hydrostatic indifference point for the circulation. The persistent distention of neck veins and change in upper body tissue compliance initiates steps to adapt to and compensate for the sensed excess fluid. These result in a loss of intravascular volume through neuro-humoral mechanisms and the presence of a smaller heart size, leading to a state where the subject has a reduced adaptive capacity to stress, particularly to fluid shifts to the lower body as occurs when once again returning to earth. This article reviews what is known about the weightlessness-induced headward fluid shift and its effects on cardiovascular function.

  3. Flow lasers. [fluid mechanics of high power continuous output operations

    NASA Technical Reports Server (NTRS)

    Christiansen, W. H.; Russell, D. A.; Hertzberg, A.

    1975-01-01

    The present work reviews the fluid-mechanical aspects of high-power continuous-wave (CW) lasers. The flow characteristics of these devices appear as classical fluid-mechanical phenomena recast in a complicated interactive environment. The fundamentals of high-power lasers are reviewed, followed by a discussion of the N2-CO2 gas dynamic laser. Next, the HF/DF supersonic diffusion laser is described, and finally the CO electrical-discharge laser is discussed.

  4. Valve operating mechanism for internal combustion engine

    SciTech Connect

    Nagahiro, K.; Ajiki, Y.; Katoh, M.; Inoue, K.

    1988-03-01

    A valve operating mechanism for operating a pair of valves of an internal combustion engine is described, comprising: a camshaft rotatable in synchronism with rotation of the internal combustion engine an having cams of different cam profiles; rocker arms held in sliding contact with the cams, respectively, for operating the valves according to the cam profiles of the cams; and means for independently selectively interconnecting and disconnecting selected of the rocker arms to operate the valves at different valve timings in low, medium and high speed ranges of the internal combustion engine.

  5. Valve operating mechanism for internal combustion engine

    SciTech Connect

    Inoue, K.; Nagahiro, K.; Ajiki, Y.; Katoh, M.

    1988-12-27

    A valve operating mechanism for operating a single valve of a particular cylinder of an internal combustion engine is described comprising: a camshaft rotatable in synchronism with rotation of the internal combustion engine; a plurality of cams on the camshaft with each of the cams bearing a different cam profile; a plurality of cam followers, each of which slidably engages one of the cams for selectively operating the valve according to the profile of the selected cam and one of which engages the valve; and means for selectively interconnecting and disconnecting the respective cam followers to operate the valve differently in different speed ranges of the internal combustion engine.

  6. Valve operating mechanism for internal combustion engine

    SciTech Connect

    Inoue, K.; Nagahiro, K.; Ajiki, Y.; Katoh, M.

    1988-12-13

    This patent describes a valve operating mechanism for operating valves of a particular cylinder of an internal combustion engine, comprising: a camshaft rotatable in synchronism with rotation of the internal combustion engine and having at least one cam; cam followers, one of which slidably engages with the cam for selectively operating the valves according to a cam profile of the cam; and means for selectively interconnecting and disconnecting the cam followers to operate the valves differently in different speed ranges of the internal combustion engine, the speed ranges including a range in which all of the valves remain inoperative.

  7. 46 CFR 12.15-13 - Deck engine mechanic.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Deck engine mechanic. 12.15-13 Section 12.15-13 Shipping... ENDORSEMENTS Qualified Member of the Engine Department § 12.15-13 Deck engine mechanic. (a) An applicant for an endorsement as deck engine mechanic shall be a person holding an MMC or MMD endorsed as junior engineer....

  8. 46 CFR 12.15-13 - Deck engine mechanic.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Deck engine mechanic. 12.15-13 Section 12.15-13 Shipping... ENDORSEMENTS Qualified Member of the Engine Department § 12.15-13 Deck engine mechanic. (a) An applicant for an endorsement as deck engine mechanic shall be a person holding an MMC or MMD endorsed as junior engineer....

  9. 46 CFR 12.15-13 - Deck engine mechanic.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 1 2013-10-01 2013-10-01 false Deck engine mechanic. 12.15-13 Section 12.15-13 Shipping... ENDORSEMENTS Qualified Member of the Engine Department § 12.15-13 Deck engine mechanic. (a) An applicant for an endorsement as deck engine mechanic shall be a person holding an MMC or MMD endorsed as junior engineer....

  10. 46 CFR 12.15-13 - Deck engine mechanic.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 1 2012-10-01 2012-10-01 false Deck engine mechanic. 12.15-13 Section 12.15-13 Shipping... ENDORSEMENTS Qualified Member of the Engine Department § 12.15-13 Deck engine mechanic. (a) An applicant for an endorsement as deck engine mechanic shall be a person holding an MMC or MMD endorsed as junior engineer....

  11. Micro electromechanical systems (MEMS) for mechanical engineers

    SciTech Connect

    Lee, A. P., LLNL

    1996-11-18

    The ongoing advances in Microelectromechanical Systems (MEMS) are providing man-kind the freedom to travel to dimensional spaces never before conceivable. Advances include new fabrication processes, new materials, tailored modeling tools, new fabrication machines, systems integration, and more detailed studies of physics and surface chemistry as applied to the micro scale. In the ten years since its inauguration, MEMS technology is penetrating industries of automobile, healthcare, biotechnology, sports/entertainment, measurement systems, data storage, photonics/optics, computer, aerospace, precision instruments/robotics, and environment monitoring. It is projected that by the turn of the century, MEMS will impact every individual in the industrial world, totaling sales up to $14 billion (source: System Planning Corp.). MEMS programs in major universities have spawned up all over the United States, preparing the brain-power and expertise for the next wave of MEMS breakthroughs. It should be pointed out that although MEMS has been initiated by electrical engineering researchers through the involvement of IC fabrication techniques, today it has evolved such that it requires a totally multi-disciplinary team to develop useful devices. Mechanical engineers are especially crucial to the success of MEMS development, since 90% of the physical realm involved is mechanical. Mechanical engineers are needed for the design of MEMS, the analysis of the mechanical system, the design of testing apparatus, the implementation of analytical tools, and the packaging process. Every single aspect of mechanical engineering is being utilized in the MEMS field today, however, the impact could be more substantial if more mechanical engineers are involved in the systems level designing. In this paper, an attempt is made to create the pathways for a mechanical engineer to enter in the MEMS field. Examples of application in optics and medical devices will be used to illustrate how mechanical

  12. The fluid mechanics of root canal irrigation.

    PubMed

    Gulabivala, K; Ng, Y-L; Gilbertson, M; Eames, I

    2010-12-01

    Root canal treatment is a common dental operation aimed at removing the contents of the geometrically complex canal chambers within teeth; its purpose is to remove diseased or infected tissue. The complex chamber is first enlarged and shaped by instruments to a size sufficient to deliver antibacterial fluids. These irrigants help to dissolve dying tissue, disinfect the canal walls and space and flush out debris. The effectiveness of the procedure is limited by access to the canal terminus. Endodontic research is focused on finding the instruments and clinical procedures that might improve success rates by more effectively reaching the apical anatomy. The individual factors affecting treatment outcome have not been unequivocally deciphered, partly because of the difficulty in isolating them and in making the link between simplified, general experimental models and the complex biological objects that are teeth. Explicitly considering the physical processes within the root canal can contribute to the resolution of these problems. The central problem is one of fluid motion in a confined geometry, which makes the dispersion and mixing of irrigant more difficult because of the absence of turbulence over much of the canal volume. The effects of treatments can be understood through the use of scale models, mathematical modelling and numerical computations. A particular concern in treatment is that caustic irrigant may penetrate beyond the root canal, causing chemical damage to the jawbone. In fact, a stagnation plane exists beyond the needle tip, which the irrigant cannot penetrate. The goal is therefore to shift the stagnation plane apically to be coincident with the canal terminus without extending beyond it. Needle design may solve some of the problems but the best design for irrigant penetration conflicts with that for optimal removal of the bacterial biofilm from the canal wall. Both irrigant penetration and biofilm removal may be improved through canal fluid

  13. Mechanical Engineering Department engineering research: Annual report, FY 1986

    SciTech Connect

    Denney, R.M.; Essary, K.L.; Genin, M.S.; Highstone, H.H.; Hymer, J.D.; Taft, S.O.

    1986-12-01

    This report provides information on the five areas of research interest in LLNL's Mechanical Engineering Department. In Computer Code Development, a solid geometric modeling program is described. In Dynamic Systems and Control, structure control and structure dynamics are discussed. Fabrication technology involves machine cutting, interferometry, and automated optical component manufacturing. Materials engineering reports on composite material research and measurement of molten metal surface properties. In Nondestructive Evaluation, NMR, CAT, and ultrasound machines are applied to manufacturing processes. A model for underground collapse is developed. Finally, an alternative heat exchanger is investigated for use in a fusion power plant. Separate abstracts were prepared for each of the 13 reports in this publication. (JDH)

  14. Problems in Microgravity Fluid Mechanics: G-Jitter Convection

    NASA Technical Reports Server (NTRS)

    Homsy, G. M.

    2005-01-01

    This is the final report on our NASA grant, Problems in Microgravity Fluid Mechanics NAG3-2513: 12/14/2000 - 11/30/2003, extended through 11/30/2004. This grant was made to Stanford University and then transferred to the University of California at Santa Barbara when the PI relocated there in January 2001. Our main activity has been to conduct both experimental and theoretical studies of instabilities in fluids that are relevant to the microgravity environment, i.e. those that do not involve the action of buoyancy due to a steady gravitational field. Full details of the work accomplished under this grant are given below. Our work has focused on: (i) Theoretical and computational studies of the effect of g-jitter on instabilities of convective states where the convection is driven by forces other than buoyancy (ii) Experimental studies of instabilities during displacements of miscible fluid pairs in tubes, with a focus on the degree to which these mimic those found in immiscible fluids. (iii) Theoretical and experimental studies of the effect of time dependent electrohydrodynamic forces on chaotic advection in drops immersed in a second dielectric liquid. Our objectives are to acquire insight and understanding into microgravity fluid mechanics problems that bear on either fundamental issues or applications in fluid physics. We are interested in the response of fluids to either a fluctuating acceleration environment or to forces other than gravity that cause fluid mixing and convection. We have been active in several general areas.

  15. Mechanical engineering capstone senior design textbook

    NASA Astrophysics Data System (ADS)

    Barrett, Rolin Farrar, Jr.

    This textbook is intended to bridge the gap between mechanical engineering equations and mechanical engineering design. To that end, real-world examples are used throughout the book. Also, the material is presented in an order that follows the chronological sequence of coursework that must be performed by a student in the typical capstone senior design course in mechanical engineering. In the process of writing this book, the author surveyed the fifty largest engineering schools (as ranked by the American Society of Engineering Education, or ASEE) to determine what engineering instructors are looking for in a textbook. The survey results revealed a clear need for a textbook written expressly for the capstone senior design course as taught throughout the nation. This book is designed to meet that need. This text was written using an organizational method that the author calls the General Topics Format. The format gives the student reader rapid access to the information contained in the text. All manufacturing methods, and some other material presented in this text, have been presented using the General Topics Format. The text uses examples to explain the importance of understanding the environment in which the product will be used and to discuss product abuse. The safety content contained in this text is unique. The Safety chapter teaches engineering ethics and includes a step-by-step guide to resolving ethical conflicts. The chapter includes explanations of rules, recommendations, standards, consensus standards, key safety concepts, and the legal implications of product failure. Key design principles have been listed and explained. The text provides easy-to-follow design steps, helpful for both the student and new engineer. Prototyping is presented as consisting of three phases: organization, building, and refining. A chapter on common manufacturing methods is included for reference.

  16. The Educational Needs of Graduate Mechanical Engineers in New Zealand.

    ERIC Educational Resources Information Center

    Deans, J.

    1999-01-01

    Surveys graduate and undergraduate mechanical engineering students at the University of Auckland. Shows that the dominant work activities of New Zealand mechanical engineers include design and consultancy and that graduate engineers rapidly migrate into management. (Author/CCM)

  17. Influence of variable thrust parameters on swirl injector fluid mechanics

    NASA Astrophysics Data System (ADS)

    Kenny, Robert J.

    Current swirl injector design methodologies do not consider elevated chamber pressure and less than design mass flow rate operation found in variable thrust liquid rocket engines. The objective of this work is to study the effects of elevated chamber pressure and off-design mass flow rate operation on swirl injector fluid mechanics. Using a high pressure chamber, water flowed through a swirl injector at various combinations of elevated chamber pressure and reduced mass flow rate. The optically-accessible swirl injector allowed for determination of the film thickness profile down the swirl injector nozzle section. High speed video and digital stills showed significant increases in the film thickness profile at high chamber pressure and low mass flow rate operation. At prescribed combinations of chamber pressure and mass flow rate, a jump was noted in the film thickness profile. This jump was assumed related to a vortex breakdown phenomenon. Measured injector discharge coefficient values showed different trends with increasing chamber pressure at low mass flow rate operation as opposed to near-design mass flow rate operation. Downstream spray angles showed classic changes in morphology as the mass flow rate was decreased below the design value. Increasing chamber pressure worked to decrease the spray angle at any injection mass flow rate. A new set of fundamental relations linking swirl injector design parameters to injector geometry and flow conditions were derived. Impacts of the research findings to the swirl injector design process were assessed.

  18. Active Learning in Fluid Mechanics: Youtube Tube Flow and Puzzling Fluids Questions

    ERIC Educational Resources Information Center

    Hrenya, Christine M.

    2011-01-01

    Active-learning exercises appropriate for a course in undergraduate fluid mechanics are presented. The first exercise involves an experiment in gravity-driven tube flow, with small groups of students partaking in a contest to predict the experimental flow rates using the mechanical energy balance. The second exercise takes the form of an…

  19. Gasoline Engine Mechanics. Performance Objectives. Basic Course.

    ERIC Educational Resources Information Center

    Jones, Marion

    Several intermediate performance objectives and corresponding criterion measures are listed for each of five terminal objectives presented in this curriculum guide for a basic gasoline engine mechanics course at the secondary level. (For the intermediate course guide see CE 010 946.) The materials were developed for a two semester (2 hours daily)…

  20. Auto Mechanics. Heavy Equipment. Small Engines.

    ERIC Educational Resources Information Center

    Finnerty, Kathy

    Developed for use in auto mechanics, Heavy Equipment Repair and Operation (HERO), and small engines programs, these study guides and supplemental worksheets cover operating principles, lubrication, cooling system, ignition circuit and electrical system, and fuel system. The worksheets and guide questions are phrased to emphasize key points…

  1. Gasoline Engine Mechanics. Performance Objectives. Intermediate Course.

    ERIC Educational Resources Information Center

    Jones, Marion

    Several intermediate performance objectives and corresponding criterion measures are listed for each of six terminal objectives presented in this curriculum guide for an intermediate gasoline engine mechanics course at the secondary level. (For the beginning course guide see CE 010 947.) The materials were developed for a two-semester (2 hour…

  2. Fluid Mechanics and Rheology of Fluid Fiber Flows: Fundamental Science and Technological Applications

    DTIC Science & Technology

    1999-01-03

    cooling phenomenon in pressure driven polymer flows , Cao et al. developed a thermal-mechanically consistent theory by postulating density a function...1, iqqfr-T>r. TT. 1998. Fluid mschanics and zfreolcgy of fluid fiH*r flows : fundaTmtal sciaxe and tedrological applications 6. AUTHOR(S) QLtfeqg...research activities are focused on modeling of polymeric liquid crystal (LCP) flows . We first summarizes our comprehensive studies on the shear and

  3. Fluid-loss mechanism for gels and suspensions

    SciTech Connect

    Medlin, W.L. ); Masse, L

    1989-11-01

    The authors present a new model of fluid loss with wall building that applies to gelled fracturing and drilling fluids. Their model separates leakoff into two parts; an invasion phase and a wall-building phase. The invasion phase begins with Darcy flow, which carries residue into pore spaces near the rock face. This phase ends when sufficient residue has accumulated to allow the formation of a wall on the rock face. Once the wall has formed, it dominates the fluid-loss mechanism through its extremely low permeability.

  4. 40 CFR 1066.145 - Test fuel, engine fluids, analytical gases, and other calibration standards.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 33 2014-07-01 2014-07-01 false Test fuel, engine fluids, analytical..., Measurement Instruments, Fuel, and Analytical Gas Specifications § 1066.145 Test fuel, engine fluids, analytical gases, and other calibration standards. (a) Test fuel. Use test fuel as specified in the...

  5. The fluid mechanics of thrombus formation

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Experimental data are presented for the growth of thrombi (blood clots) in a stagnation point flow of fresh blood. Thrombus shape, size and structure are shown to depend on local flow conditions. The evolution of a thrombus is described in terms of a physical model that includes platelet diffusion, a platelet aggregation mechanism, and diffusion and convection of the chemical species responsible for aggregation. Diffusion-controlled and convection-controlled regimes are defined by flow parameters and thrombus location, and the characteristic growth pattern in each regime is explained. Quantitative comparisons with an approximate theoretical model are presented, and a more general model is formulated.

  6. Fluid mechanics of the stagnation point flow chamber and its platelet deposition.

    PubMed

    Affeld, K; Reininger, A J; Gadischke, J; Grunert, K; Schmidt, S; Thiele, F

    1995-07-01

    The interaction of flow and thrombus generation often is a crucial question for the engineer working in the field of artificial organs. However, this interaction is only incompletely known, and quantitative data under well-defined experimental conditions are especially rare. These can be attained with the stagnation point flow chamber. This flow model applies platelet-rich plasma (PRP) as fluid. Its flow conditions are assessed with the help of computational fluid mechanics. In addition, the concept of the boundary layer is introduced, which permits assessment of the platelet flow along the wall. The results of the experiment indicate that platelets are deposited at a defined shear rate.

  7. Fluid Dynamic Mechanisms and Interactions within Separated Flows

    DTIC Science & Technology

    1993-08-01

    for this research has I been Dr. Thomas L. Doligalski, Chief, Fluid Dynamics Branch, Engineering and Environmental Sciences Division. The authors of...KOOIO, with Thomas L. gation of the Effects of a Base Cavity on the Near-Wake Flowfiel od a Body at Subsonic and Transonic Speeds," Department of...F.. Quincey , V. G., and Callinan, J., "Experiments on Flow." ARC R&M No. 3323. March 1962. Two-Dimensional Base Flow at Subsonic and Transonic Speeds

  8. STUDY OF MECHANICAL ENGINEERING FEATURES OF POLAR WATER SUPPLY

    DTIC Science & Technology

    WATER SUPPLIES, ALGAE, CHEMICAL ANALYSIS, GROWTH(PHYSIOLOGY), MECHANICAL ENGINEERING , PERMAFROST, PHYSICAL PROPERTIES, POLAR REGIONS, PURIFICATION, SANITARY ENGINEERING, WATER, WATER FILTERS, WATER SOFTENERS

  9. Fluid Mechanical Properties of Silkworm Fibroin Solutions

    NASA Astrophysics Data System (ADS)

    Matsumoto, Akira

    2005-11-01

    The aqueous solution behavior of silk fibroin is of interest due to the assembly and processing of this protein related to the spinning of protein fibers that exhibit remarkable mechanical properties. To gain insight into the origins of this functional feature, it is desired to determine how the protein behaves under a range of solution conditions. Pure fibroin at different concentrations in water was studied for surface tension, as a measure of surfactancy. In addition, shear induced changes on these solutions in terms of structure and morphology was also determined. Fibroin solutions exhibited shear rate-sensitive viscosity changes and precipitated at a critical shear rate where a dramatic increase of 75-150% of the initial value was observed along with a decrease in viscosity. In surface tension measurements, critical micelle concentrations were in the range of 3-4% w/v. The influence of additional factors, such as sericin protein, divalent and monovalent cations, and pH on the solution behavior in relation to structural and morphological features will also be described.

  10. Valve operating mechanism for internal combustion engine

    SciTech Connect

    Inoue, K.; Nagahiro, K.; Ajiki, Y.; Katoh, M.

    1988-12-06

    This patent describes a valve operating mechanism of operating valves of an internal combustion engine, comprising: a camshaft rotatable in synchronism with rotation of the internal combustion engine and having an array of three cams each having a different cam profile and including a high-speed cam position at one end of the array; three cam followers held in sliding contact with the cams, respectively, for operating the valves according to the cam profiles of the cams; and means for selectively interconnecting and disconnecting the cam followers to operate the valves at different valve timings in different speed ranges of the internal combustion engine, the speed ranges including a high-speed range in which all of the valves are controlled by the cam profile of the high-speed cam.

  11. Yielding to Stress: Recent Developments in Viscoplastic Fluid Mechanics

    NASA Astrophysics Data System (ADS)

    Balmforth, Neil J.; Frigaard, Ian A.; Ovarlez, Guillaume

    2014-01-01

    The archetypal feature of a viscoplastic fluid is its yield stress: If the material is not sufficiently stressed, it behaves like a solid, but once the yield stress is exceeded, the material flows like a fluid. Such behavior characterizes materials common in industries such as petroleum and chemical processing, cosmetics, and food processing and in geophysical fluid dynamics. The most common idealization of a viscoplastic fluid is the Bingham model, which has been widely used to rationalize experimental data, even though it is a crude oversimplification of true rheological behavior. The popularity of the model is in its apparent simplicity. Despite this, the sudden transition between solid-like behavior and flow introduces significant complications into the dynamics, which, as a result, has resisted much analysis. Over recent decades, theoretical developments, both analytical and computational, have provided a better understanding of the effect of the yield stress. Simultaneously, greater insight into the material behavior of real fluids has been afforded by advances in rheometry. These developments have primed us for a better understanding of the various applications in the natural and engineering sciences.

  12. Computational fluid dynamic design of rocket engine pump components

    NASA Technical Reports Server (NTRS)

    Chen, Wei-Chung; Prueger, George H.; Chan, Daniel C.; Eastland, Anthony H.

    1992-01-01

    Integration of computational fluid dynamics (CFD) for design and analysis of turbomachinery components is needed as the requirements of pump performance and reliability become more stringent for the new generation of rocket engine. A fast grid generator, designed specially for centrifugal pump impeller, which allows a turbomachinery designer to use CFD to optimize the component design will be presented. The CFD grid is directly generated from the impeller blade G-H blade coordinates. The grid points are first generated on the meridional plane with the desired clustering near the end walls. This is followed by the marching of grid points from the pressure side of one blade to the suction side of a neighboring blade. This fast grid generator has been used to optimize the consortium pump impeller design. A grid dependency study has been conducted for the consortium pump impeller. Two different grid sizes, one with 10,000 grid points and one with 80,000 grid points were used for the grid dependency study. The effects of grid resolution on the turnaround time, including the grid generation and completion of the CFD analysis, is discussed. The impeller overall mass average performance is compared for different designs. Optimum design is achieved through systematic change of the design parameters. In conclusion, it is demonstrated that CFD can be effectively used not only for flow analysis but also for design and optimization of turbomachinery components.

  13. Internal fluid mechanics research on supercomputers for aerospace propulsion systems

    NASA Technical Reports Server (NTRS)

    Miller, Brent A.; Anderson, Bernhard H.; Szuch, John R.

    1988-01-01

    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 mechanics (ICFM) to a state of practical application for aerospace propulsion systems. The strategies used to achieve this goal are to: (1) pursue an understanding of flow physics, surface heat transfer, and combustion via analysis and fundamental experiments, (2) incorporate improved understanding of these phenomena into verified 3-D CFD codes, and (3) utilize state-of-the-art computational technology to enhance experimental and CFD research. Presented is an overview of the ICFM program in high-speed propulsion, including work in inlets, turbomachinery, and chemical reacting flows. Ongoing efforts to integrate new computer technologies, such as parallel computing and artificial intelligence, into high-speed aeropropulsion research are described.

  14. Engineering Design Handbook. Breech Mechanism Design

    DTIC Science & Technology

    1979-02-01

    to contain the high propellant pre -sures the block i3 first unlocked by a limited rotation developed in the weapon chamber. then swung out of the...system oriented engineering data and It is in this area where innovative uses of internal related characteristics of both current and pre - power to...I io 10 rounds provide adequate support for the case and pre - per minute. Mechanization is provided for vent its rearward displacement or rupture. 41

  15. Leonhard Euler and his contributions to fluid mechanics

    NASA Technical Reports Server (NTRS)

    Salas, M. D.

    1988-01-01

    The career of Leonhard Euler, one of the world's most gifted scientists, is reviewed. The paper focuses on Euler's contributions to fluid mechanics and gives a perspective of how this science was born. A bibliography is included to provide the history enthusiast with a starting point for further study.

  16. Flippin' Fluid Mechanics--Comparison Using Two Groups

    ERIC Educational Resources Information Center

    Webster, Donald R.; Majerich, David M.; Madden, Amanda G.

    2016-01-01

    A flipped classroom approach was implemented in an undergraduate fluid mechanics course. Students watched short, online video lectures before class, participated in active in-class problem solving sessions (in pairs), and completed individualized online quizzes weekly. In-class activities were designed to develop problem-solving skills and teach…

  17. Fluid Mechanics of Wing Adaptation for Separation Control

    NASA Technical Reports Server (NTRS)

    Chandrasekhara, M. S.; Wilder, M. C.; Carr, L. W.; Davis, Sanford S. (Technical Monitor)

    1997-01-01

    The unsteady fluid mechanics associated with use of a dynamically deforming leading edge airfoil for achieving compressible flow separation control has been experimentally studied. Changing the leading edge curvature at rapid rates dramatically alters the flow vorticity dynamics which is responsible for the many effects observed in the flow.

  18. Fluid Assisted Fault Weakening: Mechanical vs. Chemical Processes

    NASA Astrophysics Data System (ADS)

    Collettini, C.

    2011-12-01

    The influx of fluids into fault zones can trigger two main types of weakening process that operate over different timescales, facilitate fault movement and influence fault slip behaviour. During the seismic cycle fluids can be trapped by low permeability fault zones or stratigraphic barriers favoring fluid overpressure (mechanical weakening) and earthquake nucleation. In the entire fault history fluids can react with fault rocks to produce weak mineral phases (chemical weakening) that alter the mechanical properties of the fault zones. Here I will present two examples of mechanical and chemical fault-weakening from the Apennines of Italy. Seismic profiles and deep borehole data show that the strongest earthquakes of the Apennines nucleate within overpressured Evaporites consisting of dolostones and anhydrites. Field and experimental studies on exhumed faults within the same lithology depict a cataclastic inner fault that can generate frictional instabilities with localization and increasing sliding velocity. The outer fault core presents barrier-like portions associated with foliated anhydrites, 10-21 ≤ permeability ≤10-19 m2. The combination of field observations and rock deformation measurements suggests a fault zone structure capable of developing fluid overpressures during the seismic cycle: fluid overpressures can potentially promote earthquake nucleation and aftershock triggering. Field studies from an exhumed regional low-angle normal fault show that in the long term fluids reacted (diffusion-mass transfer processes) with fine-grained cataclasites in the fault core to produce a phyllosilicates-rich and foliated fault rock. Within the foliated microstructure, that is rich in talc, smectite and chlorite, deformation occurs by frictional sliding along 50-200-nm-thick lamellae. Rock deformation experiments show that the foliated fault rock is weak, 0.2 < friction< 0.35, it is characterized by a stable sliding slip-behaviour with no strength recovery with

  19. Oscillatory fluid flow influences primary cilia and microtubule mechanics.

    PubMed

    Espinha, Lina C; Hoey, David A; Fernandes, Paulo R; Rodrigues, Hélder C; Jacobs, Christopher R

    2014-07-01

    Many tissues are sensitive to mechanical stimuli; however, the mechanotransduction mechanism used by cells remains unknown in many cases. The primary cilium is a solitary, immotile microtubule-based extension present on nearly every mammalian cell which extends from the basal body. The cilium is a mechanosensitive organelle and has been shown to transduce fluid flow-induced shear stress in tissues, such as the kidney and bone. The majority of microtubules assemble from the mother centriole (basal body), contributing significantly to the anchoring of the primary cilium. Several studies have attempted to quantify the number of microtubules emanating from the basal body and the results vary depending on the cell type. It has also been shown that cellular response to shear stress depends on microtubular integrity. This study hypothesizes that changing the microtubule attachment of primary cilia in response to a mechanical stimulus could change primary cilia mechanics and, possibly, mechanosensitivity. Oscillatory fluid flow was applied to two different cell types and the microtubule attachment to the ciliary base was quantified. For the first time, an increase in microtubules around primary cilia both with time and shear rate in response to oscillatory fluid flow stimulation was demonstrated. Moreover, it is presented that the primary cilium is required for this loading-induced cellular response. This study has demonstrated a new role for the cilium in regulating alterations in the cytoplasmic microtubule network in response to mechanical stimulation, and therefore provides a new insight into how cilia may regulate its mechanics and thus the cells mechanosensitivity.

  20. Rotor noise due to atmospheric turbulence ingestion. I - Fluid mechanics

    NASA Technical Reports Server (NTRS)

    Simonich, J. C.; Amiet, R. K.; Schlinker, R. H.; Greitzer, E. M.

    1986-01-01

    In the present analytical procedure for the prediction of helicopter rotor noise generation due to the ingestion of atmospheric turbulence, different models for turbulence fluid mechanics and the ingestion process are combined. The mean flow and turbulence statistics associated with the atmospheric boundary layer are modeled with attention to the effects of atmospheric stability length, windspeed, and altitude. The turbulence field can be modeled as isotropic, locally stationary, and homogeneous. For large mean flow contraction ratios, accurate predictions of turbulence vorticity components at the rotor face requires the incorporation of the differential drift of fluid particles on adjacent streamlines.

  1. 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.

  2. Testing of the Multi-Fluid Evaporator Engineering Development Unit

    NASA Technical Reports Server (NTRS)

    Quinn, Gregory; O'Connor, Ed; Riga, Ken; Anderson, Molly; Westheimer, David

    2007-01-01

    Hamilton Sundstrand is under contract with the NASA Johnson Space Center to develop a scalable, evaporative heat rejection system called the Multi-Fluid Evaporator (MFE). It is being designed to support the Orion Crew Module and to support future Constellation missions. The MFE would be used from Earth sea level conditions to the vacuum of space. The current Shuttle configuration utilizes an ammonia boiler and flash evaporator system to achieve cooling at all altitudes. The MFE system combines both functions into a single compact package with significant weight reduction and improved freeze-up protection. The heat exchanger core is designed so that radial flow of the evaporant provides increasing surface area to keep the back pressure low. The multiple layer construction of the core allows for efficient scale up to the desired heat rejection rate. The full scale MFE prototype will be constructed with four core sections that, combined with a novel control scheme, manage the risk of freezing the heat exchanger cores. A sub-scale MFE engineering development unit (EDU) has been built, and is identical to one of the four sections of a full scale prototype. The EDU has completed testing at Hamilton Sundstrand. The overall test objective was to determine the thermal performance of the EDU. The first set of tests simulated how each of the four sections of the prototype would perform by varying the chamber pressure, evaporant flow rate, coolant flow rate and coolant temperature. A second set of tests was conducted with an outlet steam header in place to verify that the outlet steam orifices prevent freeze-up in the core while also allowing the desired thermal turn-down ratio. This paper discusses the EDU tests and results.

  3. Fluid mechanics mechanisms in the stall process of helicopters

    NASA Technical Reports Server (NTRS)

    Young, W. H., Jr.

    1981-01-01

    Recent experimental results from airfoils in the Mach number, Reynolds number, or reduced frequency ranges typical of helicopter rotor blades have identified the most influential flow mechanisms in the dynamic stall process. The importance of secondary shed vortices, downstream wake action, and the flow in the separated region is generally acknowledged but poorly understood. By means of surface pressure cross-correlations and flow field measurements in static stall, several new hypotheses have been generated. It is proposed that vortex shedding may be caused by acoustic disturbances propagating forward in the lower (pressure) surface boundary layer, that wake closure is a misnomer, and that the shed vortex leaves a trail of vorticity that forms a turbulent free shear layer. The known dynamic stall flow mechanisms are reviewed and the potential importance of recently proposed and hypothetical flow phenomena with respect to helicopter blade aeroelastic response are assessed.

  4. Characterization of the Mechanical Properties of Electrorheological Fluids Made of Starch and Silicone Fluid

    NASA Astrophysics Data System (ADS)

    Vieira, Sheila Lopes; de Arruda, Antonio Celso Fonseca

    In the majority of published articles on the topic, ER fluids have been studied as if they were viscous liquids. In this work, electrorheological fluids were characterized as solids and their mechanical properties were determined. The results infer that ER materials are controllably resistant to compression, tensile and shear stress, in this order of magnitude. More precisely, fluids made of starch have elasticity modulus similar to that of rubber, they have tensile strength 103 to 5×104 times lower than that of low density polyethylene (LDPE), static yield stress 4×104 to 8×105 times lower than that of acrylonitrile-butadiene-styrene terpolymer (ABS) and fatigue life similar to some polymers like polyethylene(PE) and polypropylene (PP).

  5. A fluid mechanical model for current-generating-feeding jellyfish

    NASA Astrophysics Data System (ADS)

    Peng, Jifeng; Dabiri, John

    2008-11-01

    Many jellyfish species, e.g. moon jellyfish Aurelia aurita, use body motion to generate fluid currents which carry their prey to the vicinity of their capture appendages. In this study, a model was developed to understand the fluid mechanics for this current-generating-feeding mode of jellyfish. The flow generated by free-swimming Aurelia aurita was measured using digital particle image velocimetry. The dynamics of prey (e.g., brine shrimp Artemia) in the flow field were described by a modified Maxey-Riley equation which takes into consideration the inertia of prey and the escape forces, which prey exert in the presence of predator. A Lagrangian analysis was used to identify the region of the flow in which prey can be captured by the jellyfish and the clearance rate was quantified. The study provides a new methodology to study biological current-generating-feeding and the transport and mixing of particles in fluid flow in general.

  6. Selective Guide to Literature on Mechanical Engineering. Engineering Literature Guides, Number 2.

    ERIC Educational Resources Information Center

    Franklin, Hugh Lockwood, Comp.

    Mechanical engineering has become highly interdisciplinary. It would not be possible to single out particular reference sources that are uniquely applicable to mechanical engineering. For the purpose of this guide, mechanical engineering deals with the generation, transmission and utilization of heat and mechanical power and with the production of…

  7. Working fluid selection for the Organic Rankine Cycle (ORC) exhaust heat recovery of an internal combustion engine power plant

    NASA Astrophysics Data System (ADS)

    Douvartzides, S.; Karmalis, I.

    2016-11-01

    Organic Rankine cycle technology is capable to efficiently convert low-grade heat into useful mechanical power. In the present investigation such a cycle is used for the recovery of heat from the exhaust gases of a four stroke V18 MAN 51/60DF internal combustion engine power plant operating with natural gas. Design is focused on the selection of the appropriate working fluid of the Rankine cycle in terms of thermodynamic, environmental and safety criteria. 37 candidate fluids have been considered and all Rankine cycles examined were subcritical. The thermodynamic analysis of all fluids has been comparatively undertaken and the effect of key operation conditions such as the evaporation pressure and the superheating temperature was taken into account. By appropriately selecting the working fluid and the Rankine cycle operation conditions the overall plant efficiency was improved by 5.52% and fuel consumption was reduced by 12.69%.

  8. Fluid coupling in a discrete model of cochlear mechanics.

    PubMed

    Elliott, Stephen J; Lineton, Ben; Ni, Guangjian

    2011-09-01

    A discrete model of cochlear mechanics is introduced that includes a full, three-dimensional, description of fluid coupling. This formulation allows the fluid coupling and basilar membrane dynamics to be analyzed separately and then coupled together with a simple piece of linear algebra. The fluid coupling is initially analyzed using a wavenumber formulation and is separated into one component due to one-dimensional fluid coupling and one comprising all the other contributions. Using the theory of acoustic waves in a duct, however, these two components of the pressure can also be associated with a far field, due to the plane wave, and a near field, due to the evanescent, higher order, modes. The near field components are then seen as one of a number of sources of additional longitudinal coupling in the cochlea. The effects of non-uniformity and asymmetry in the fluid chamber areas can also be taken into account, to predict both the pressure difference between the chambers and the mean pressure. This allows the calculation, for example, of the effect of a short cochlear implant on the coupled response of the cochlea.

  9. Synthesis and Engineering Materials Properties of Fluid Phase Chemical Hydrogen Storage Materials for Automotive Applications

    SciTech Connect

    Choi, Young Joon; Westman, Matthew P.; Karkamkar, Abhijeet J.; Chun, Jaehun; Ronnebro, Ewa

    2015-09-01

    Among candidates for chemical hydrogen storage in PEM fuel cell automotive applications, ammonia borane (AB, NH3BH3) is considered to be one of the most promising materials due to its high practical hydrogen content of 14-16 wt%. This material is selected as a surrogate chemical for a hydrogen storage system. For easier transition to the existing infrastructure, a fluid phase hydrogen storage material is very attractive and thus, we investigated the engineering materials properties of AB in liquid carriers for a chemical hydrogen storage slurry system. Slurries composed of AB and high temperature liquids were prepared by mechanical milling and sonication in order to obtain stable and fluidic properties. Volumetric gas burette system was adopted to observe the kinetics of the H2 release reactions of the AB slurry and neat AB. Viscometry and microscopy were employed to further characterize slurries engineering properties. Using a tip-sonication method we have produced AB/silicone fluid slurries at solid loadings up to 40wt% (6.5wt% H2) with viscosities less than 500cP at 25°C.

  10. Thermal and Fluids Engineering at Dryden Flight Research Center in 2008

    NASA Technical Reports Server (NTRS)

    Kostyk, christopher

    2008-01-01

    This viewgraph presentation reviews thermal structures and fluids engineering at NASA Dryden Research Center. The contents include: 1) SOFIA; 2) In-Flight Infrared Thermography Boundary Layer Transition Measurement; 3) Thermal Testing; and 4) Aerodynamic Heating Analysis.

  11. Effect of Chamber Backpressure on Swirl Injector Fluid Mechanics

    NASA Technical Reports Server (NTRS)

    Kenny, R. Jeremy; Hulka, James R.; Moser, Marlow D.; Rhys, Noah O.

    2008-01-01

    A common propellant combination used for high thrust generation is GH2/LOX. Historical GH2/LOX injection elements have been of the shear-coaxial type. Element type has a large heritage of research work to aid in element design. The swirl-coaxial element, despite its many performance benefits, has a relatively small amount of historical, LRE-oriented work to draw from. Design features of interest are grounded in the fluid mechanics of the liquid swirl process itself, are based on data from low-pressure, low mass flow rate experiments. There is a need to investigate how high ambient pressures and mass flow rates influence internal and external swirl features. The objective of this research is to determine influence of varying liquid mass flow rate and ambient chamber pressure on the intact-length fluid mechanics of a liquid swirl element.

  12. Experimental Fluid Mechanics of Pulsatile Artificial Blood Pumps

    NASA Astrophysics Data System (ADS)

    Deutsch, Steven; Tarbell, John M.; Manning, Keefe B.; Rosenberg, Gerson; Fontaine, Arnold A.

    2006-01-01

    The fluid mechanics of artificial blood pumps has been studied since the early 1970s in an attempt to understand and mitigate hemolysis and thrombus formation by the device. Pulsatile pumps are characterized by inlet jets that set up a rotational "washing" pattern during filling. Strong regurgitant jets through the closed artificial heart valves have Reynolds stresses on the order of 10,000 dynes/cm2 and are the most likely cause of red blood cell damage and platelet activation. Although the flow in the pump chamber appears benign, low wall shear stresses throughout the pump cycle can lead to thrombus formation at the wall of the smaller pumps (10 50 cc). The local fluid mechanics is critical. There is a need to rapidly measure or calculate the wall shear stress throughout the device so that the results may be easily incorporated into the design process.

  13. Analysis of heat recovery of diesel engine using intermediate working fluid

    NASA Astrophysics Data System (ADS)

    Jin, Lei; Zhang, Jiang; Tan, Gangfeng; Liu, Huaming

    2017-02-01

    The organic Rankine cycle (ORC) is an effective way to recovery the engine exhaust heat. The thermal stability of the evaporation system is significant for the stable operation of the ORC system. In this paper, the performance of the designed evaporation system which combines with the intermediate fluid for recovering the exhaust waste heat from a diesel engine is evaluated. The thermal characteristics of the target diesel engine exhaust gas are evaluated based on the experimental data firstly. Then, the mathematical model of the evaporation system is built based on the geometrical parameters and the specific working conditions of ORC. Finally, the heat transfer characteristics of the evaporation system are estimated corresponding to three typical operating conditions of the diesel engine. The result shows that the exhaust temperature at the evaporator outlet increases slightly with the engine speed and load. In the evaporator, the heat transfer coefficient of the Rankine working fluid is slightly larger than the intermediate fluid. However, the heat transfer coefficient of the intermediate fluid in the heat exchanger is larger than the exhaust side. The heat transfer areas of the evaporator in both the two-phase zone and the preheated zone change slightly along with the engine working condition while the heat transfer areas of the overheated zone has changed obviously. The maximum heat transfer rate occurs in the preheating zone while the minimum value occurs in the overheating zone. In addition, the Rankine working fluid temperature at the evaporator outlet is not sensitively affected by the torque and speed of the engine and the organic fluid flow is relatively stable. It is concluded that the intermediate fluid could effectively reduce the physical changes of Rankine working fluid in the evaporator outlet due to changes in engine operating conditions.

  14. The low temperature differential Stirling engine with working fluid operated on critical condition

    SciTech Connect

    Naso, V.; Dong, W.; Lucentini, M.; Capata, R.

    1998-07-01

    The research and development of low temperature differential Stirling engine has a great potential market since a lot of thermal energy at low temperature can supply it and the cost of this kind of engine is lower than general Stirling engine. The characteristics of low compression ratio and low differential temperature Stirling engine may be satisfied with working fluid compressed on critical conditions. By combining two phase heat transfer with forced convective flow in compression space and through the regenerator in the engine, a new heat transfer coefficient emerges capable of absorbing and releasing high heat fluxes without the corresponding low temperature increase. The current analysis focuses on the study of Stirling engines with working fluid compressed on critical conditions, thus at two-phase heat transfer in compression space and regenerator of the engine under forced convective flow conditions.

  15. Balancing mechanism for reciprocating piston engine

    SciTech Connect

    Murata, N.; Ogino, T.

    1987-04-14

    This patent describes a balancing mechanism for a reciprocating piston internal combustion engine which includes a cylinder, a piston reciprocatable in the cylinder, a crankcase, a crankshaft mounted in the crankshaft, a crankpin connected to the piston, and a pair of crank arms bridging the crankshaft and crankpin. The crank arms and crankpin rotate with the crankshaft during operation and form a rotating mass. The balancing mechanism comprises at least one rotating counterweight attached to and rotating with the crankshaft, and eccentric journal means on the crankshaft adjacent the crank arms, rotating with the crankshaft. The journal means has an axis spaced to the side of the crankshaft axis which is opposite from the crankpin. The rotating counterweight and the eccentric journal means counterbalancing the rotating mass.

  16. Stirling engine control mechanism and method

    DOEpatents

    Dineen, John J.

    1983-01-01

    A reciprocating-to-rotating motion conversion and power control device for a Stirling engine includes a hub mounted on an offset portion of the output shaft for rotation relative to the shaft and for sliding motion therealong which causes the hub to tilt relative to the axis of rotation of the shaft. This changes the angle of inclination of the hub relative to the shaft axis and changes the axial stroke of a set of arms connected to the hub and nutating therewith. A hydraulic actuating mechanism is connected to the hub for moving its axial position along the shaft. A balancing wheel is linked to the hub and changes its angle of inclination as the angle of inclination of the hub changes to maintain the mechanism in perfect balance throughout its range of motion.

  17. A statistical mechanics approach to mixing in stratified fluids

    NASA Astrophysics Data System (ADS)

    Venaille, A.; Gostiaux, L.; Sommeria, J.

    2017-01-01

    Predicting how much mixing occurs when a given amount of energy is injected into a Boussinesq fluid is a longstanding problem in stratified turbulence. The huge number of degrees of freedom involved in those processes renders extremely difficult a deterministic approach to the problem. Here we present a statistical mechanics approach yielding prediction for a cumulative, global mixing efficiency as a function of a global Richardson number and the background buoyancy profile.

  18. Fluid mechanics and solidification investigations in low-gravity environments

    NASA Technical Reports Server (NTRS)

    Fichtl, G. H.; Lundquist, C. A.; Naumann, R. J.

    1980-01-01

    Fluid mechanics of gases and liquids and solidification processes were investigated under microgravity conditions during Skylab and Apollo-Soyuz missions. Electromagnetic, acoustic, and aerodynamic levitation devices, drop tubes, aircraft parabolic flight trajectories, and vertical sounding rockets were developed for low-g simulation. The Spacelab 3 mission will be carried out in a gravity gradient flight attitude; analyses of sources of vehicle dynamic accelerations with associated g-levels and angular rates will produce results for future specific experiments.

  19. Aeropropulsion 1987. Session 3: Internal Fluid Mechanics Research

    NASA Technical Reports Server (NTRS)

    1987-01-01

    Internal fluid mechanics research at Lewis is directed toward an improved understanding of the important flow physics affecting aerospace propulsion systems, and applying this improved understanding to formulate accurate predictive codes. To this end, research is conducted involving detailed experimentation and analysis. The presentations in this session summarize ongoing work and indicated future emphasis in three major research thrusts: namely, inlets, ducts, and nozzles; turbomachinery; and chemical reacting flows.

  20. Fluid mechanics mechanisms in the stall process of airfoils for helicopters

    NASA Technical Reports Server (NTRS)

    Young, W. H., Jr.

    1981-01-01

    Phenomena that control the flow during the stall portion of a dynamic stall cycle are analyzed, and their effect on blade motion is outlined. Four mechanisms by which dynamic stall may be initiated are identified: (1) bursting of the separation bubble, (2) flow reversal in the turbulent boundary layer on the airfoil upper surface, (3) shock wave-boundary layer interaction behind the airfoil crest, and (4) acoustic wave propagation below the airfoil. The fluid mechanics that contribute to the identified flow phenomena are summarized, and the usefulness of a model that incorporates the required fluid mechanics mechanisms is discussed.

  1. Advances in cardiovascular fluid mechanics: bench to bedside.

    PubMed

    Dasi, Lakshmi P; Sucosky, Philippe; de Zelicourt, Diane; Sundareswaran, Kartik; Jimenez, Jorge; Yoganathan, Ajit P

    2009-04-01

    This paper presents recent advances in cardiovascular fluid mechanics that define the current state of the art. These studies include complex multimodal investigations with advanced measurement and simulation techniques. We first discuss the complex flows within the total cavopulmonary connection in Fontan patients. We emphasize the quantification of energy losses by studying the importance of caval offsets as well as the differences among various Fontan surgical protocols. In our studies of the fluid mechanics of prosthetic heart valves, we reveal for the first time the full three-dimensional complexity of flow fields in the vicinity of bileaflet and trileaflet valves and the microscopic hinge flow dynamics. We also present results of these valves functioning in a patient-specific native aorta geometry. Our in vitro mitral valve studies show the complex mechanism of the native mitral valve apparatus. We demonstrate that the different components of the mitral valve have independent and synergistically complex functions that allow the valve to operate efficiently. We also show how valve mechanics change under pathological and repair conditions associated with enlarged ventricles. Finally, our ex vivo studies on the interactions between the aortic valve and its surrounding hemodynamic environment are aimed at providing insights into normal valve function and valve pathology. We describe the development of organ- and tissue-culture systems and the biological response of the tissue subjected to their respective simulated mechanical environment. The studies noted above have enhanced our understanding of the complex fluid mechanics associated with the cardiovascular system and have led to new translational technologies.

  2. Oscillatory Fluid Flow Influences Primary Cilia and Microtubule Mechanics

    PubMed Central

    Espinha, Lina C.; Hoey, David A.; Fernandes, Paulo R.; Rodrigues, Hélder C.; Jacobs, Christopher R.

    2014-01-01

    Many tissues are sensitive to mechanical stimuli; however, the mechanotransduction mechanism used by cells remains unknown in many cases. The primary cilium is a solitary, immotile microtubule-based extension present on nearly every mammalian cell which extends from the basal body. The cilium is a mechanosensitive organelle and has been shown to transduce fluid flow-induced shear stress in tissues such as the kidney and bone. The majority of microtubules assemble from the mother centriole (basal body), contributing significantly to the anchoring of the primary cilium. Several studies have attempted to quantify the number of microtubules emanating from the basal body and the results vary depending on the cell type. It has also been shown that cellular response to shear stress depends on microtubular integrity. This study hypothesizes that changing the microtubule attachment of primary cilia in response to a mechanical stimulus could change primary cilia mechanics and, possibly, mechanosensitivity. Oscillatory fluid flow was applied to two different cell types and the microtubule attachment to the ciliary base was quantified. For the first time, an increase in microtubules around primary cilia both with time and shear rate in response to oscillatory fluid flow stimulation was demonstrated. Moreover, it is presented that the primary cilium is required for this loading-induced cellular response. This study has demonstrated a new role for the cilium in regulating alterations in the cytoplasmic microtubule network in response to mechanical stimulation, and therefore provides a new insight into how cilia may regulate its mechanics and thus the cells mechanosensitivity. PMID:25044764

  3. Fluid mechanics of eating, swallowing and digestion - overview and perspectives.

    PubMed

    Engmann, Jan; Burbidge, Adam S

    2013-02-26

    From a very simplistic viewpoint, the human digestive system can be regarded as a long tube (with dramatic variations in diameter, cross-section, wall properties, pumping mechanisms, regulating valves and in-line sensors). We single out a few fluid mechanical phenomena along the trajectory of a food bolus from the mouth to the small intestine and discuss how they influence sensorial perception, safe transport, and nutrient absorption from a bolus. The focus is on lubrication flows between the tongue and palate, the oropharyngeal stage of swallowing and effects of flow on absorption in the small intestine. Specific challenges and opportunities in this research area are highlighted.

  4. Fluid Mechanics and Heat Transfer Spirally Fluted Tubing,

    DTIC Science & Technology

    1981-08-01

    rolling flutes on strip and subsequently spiralling and simultaneously welding the strip to form tubing results in low fabrication costs. approximately...AD-AI07 983 GENERAL ATOMIC CO SAN DIEGO CALIF FIG 20/4 FLUI D MECHANICS AND HEAT TRANSFER SPIRALLY FLUTED TUBING,(U) AUG 81 J C LARUE, P A LIBBY. J S...YAMPOLSKY N0001-79-C0773 UNCLASSIFIED GA-A6541 NL II- "N m oom o 1111_____ ~fI.2.. 1 1. GA-Al6541 LEVEL"’ FLUID MECHANICS AND HEAT TRANSFER SPIRALLY

  5. The fluid mechanics of the inner-ear disorder BPPV

    NASA Astrophysics Data System (ADS)

    Weidman, Michael; Squires, Todd; Stone, Howard

    2001-11-01

    The inner ear of mammals contains fluid-filled semi-circular canals with a flexible sensory membrane (called a cupula) which detects rotational acceleration. Benign Paroxysmal Positional Vertigo (BPPV) is one of the most common disorders of this system diagnosed today, and is characterized by symptoms of dizziness and nausea brought on by sudden changes in head orientation. BPPV is believed to have a mechanical (rather than nervous) origin, in which dense particles called otoconia settle into the canals and trigger false sensations of rotational acceleration. Several qualitative mechanisms have been proposed by the medical community, which we examine from a fluid mechanical standpoint. Traditionally, the semicircular canal and the cupula are modeled as an over-damped torsional pendulum with a driving force provided by rotational acceleration. We extend this model to include the time-dependent mechanical response owing to sedimentation of the otoconia. We make qualitative and quantitative predictions associated with the proposed mechanisms, with an eye towards differentiating between them and perhaps towards more effective diagnostic and therapeutic methods.

  6. Dynamical density functional theory for molecular and colloidal fluids: a microscopic approach to fluid mechanics.

    PubMed

    Archer, A J

    2009-01-07

    In recent years, a number of dynamical density functional theories (DDFTs) have been developed for describing the dynamics of the one-body density of both colloidal and atomic fluids. In the colloidal case, the particles are assumed to have stochastic equations of motion and theories exist for both the case when the particle motion is overdamped and also in the regime where inertial effects are relevant. In this paper, we extend the theory and explore the connections between the microscopic DDFT and the equations of motion from continuum fluid mechanics. In particular, starting from the Kramers equation, which governs the dynamics of the phase space probability distribution function for the system, we show that one may obtain an approximate DDFT that is a generalization of the Euler equation. This DDFT is capable of describing the dynamics of the fluid density profile down to the scale of the individual particles. As with previous DDFTs, the dynamical equations require as input the Helmholtz free energy functional from equilibrium density functional theory (DFT). For an equilibrium system, the theory predicts the same fluid one-body density profile as one would obtain from DFT. Making further approximations, we show that the theory may be used to obtain the mode coupling theory that is widely used for describing the transition from a liquid to a glassy state.

  7. Engineering and Characterization of Simplified Vaginal and Seminal Fluid Simulants

    PubMed Central

    Rastogi, Rachna; Su, Jonathan; Mahalingam, Alamelu; Clark, Justin; Sung, Samuel; Hope, Thomas; Kiser, Patrick F.

    2016-01-01

    BACKGROUND Reported vaginal and seminal fluid simulants have complex compositions with multiple preparatory steps which contribute to physical instability. We report the design and characterization of stable and simplified buffers that mimic the salient physical-chemical properties of the physiological fluids. STUDY DESIGN/METHODS Human cervicovaginal and seminal fluid samples were collected and buffering capacity was determined. The major buffering species were identified from published compositions of reproductive tract fluids. These values were used to compute the composition of vaginal and seminal fluid simulants. Ionic strength, buffering capacities, pH and osmolalities were then calculated or experimentally determined. Finally, cytotoxicity was evaluated in HEC-1-A cells and 3D reconstructed EpiVaginal™tissue (VEC-100-FT) using naïve cells/tissue and nonoxynol-9 as controls. RESULTS The use of calculated amounts of conjugate acid and base for buffer development resulted in compositions that did not require end point pH adjustment and could be formulated as stable 10X concentrates. Furthermore, due to the absence of complex divalent salts, all our proposed simulants were stable at 4°C for 1 month whereas precipitation, and pH and osmolality changes were noted in reported buffers. Experimental determination of buffering capacities yielded similar values for undiluted cervicovaginal fluid (β4.2–5.2 = 35.6 ± 12.3 mM, N = 7) and human seminal fluid (β7–6 =37.5 ± 5 mM, N = 3). All neat simulants showed significant cytotoxicity in HEC-1-A cells but were well tolerated by organotypic vaginal tissue. CONCLUSIONS We report revised and improved compositions of buffers mimicking salient properties of vaginal and seminal fluid necessary for in vitro product evaluation. PMID:26585883

  8. An Innovative Improvement of Engineering Learning System Using Computational Fluid Dynamics Concept

    ERIC Educational Resources Information Center

    Hung, T. C.; Wang, S. K.; Tai, S. W.; Hung, C. T.

    2007-01-01

    An innovative concept of an electronic learning system has been established in an attempt to achieve a technology that provides engineering students with an instructive and affordable framework for learning engineering-related courses. This system utilizes an existing Computational Fluid Dynamics (CFD) package, Active Server Pages programming,…

  9. Fluid mechanics and heat transfer spirally fluted tubing

    NASA Astrophysics Data System (ADS)

    Larue, J. C.; Libby, P. A.; Yampolsky, J. S.

    1981-08-01

    The objective of this program is to develop both a qualitative and a quantitative understanding of the fluid mechanics and heat transfer mechanisms that underlie the measured performance of the spirally fluted tubes under development at General Atomic. The reason for the interest in the spirally fluted tubes is that results to date have indicated three advantages to this tubing concept: The fabrication technique of rolling flutes on strip and subsequently spiralling and simultaneously welding the strip to form tubing results in low fabrication costs, approximately equal to those of commercially welded tubing. The heat transfer coefficient is increased without a concomitant increase of the friction coefficient on the inside of the tube. In single-phase axial flow of water, the helical flutes continuously induce rotation of the flow both within and without the tube as a result of the effect of curvature. An increase in condensation heat transfer on the outside of the tube is achieved. In a vertical orientation with fluid condensing on the outside of the helically fluted tube, the flutes provide a channel for draining the condensed fluid.

  10. Development of peristaltic crawling robot using magnetic fluid on the basis of locomotion mechanism of earthworm

    NASA Astrophysics Data System (ADS)

    Saga, Norihiko; Nakamura, Taro

    2002-11-01

    The field of bio-engineering with the aim of developing new machines, which utilizes the motion and control of organisms as a model, is attracting attention. This technology is pursued by paying attention to various shapes and movements of organisms and autonomous system of organisms in acting in response to environment surrounding them, and by mechanically elucidating the locomotion mechanism, propulsive mechanism, nerve system and sensation system of these organisms. On the other hand, in the field of hydrodynamics, magnetic fluid that changes its apparent viscosity depending on magnetic field has been developed, and its utilization is under trial in various fields. We paid attention to the peristaltic crawling of earthworm as transport function in place of wheels or ambulation, and have developed a micro robot running inside a tube using magnetic fluid. In this micro robot, a cell corresponding to earthworm's segment is composed of a natural rubber tube sealed with water-based magnetic fluid, and the cells are connected with elastic rods made of natural rubber. The feature of this micro robot is that its structure is simply composed of, and it can be controlled with external wireless force, by providing it with moving magnetism from the outside. This paper presents the analytical result of the peristaltic crawling of an actual earthworm and the evaluation result of transport mechanism of a prototype micro robot moved by external magnetic field.

  11. Fluid mechanics in crystal growth - The 1982 Freeman scholar lecture

    NASA Technical Reports Server (NTRS)

    Ostrach, S.

    1983-01-01

    An attempt is made to unify the current state of knowledge in crystal growth techniques and fluid mechanics. After identifying important fluid dynamic problems for such representative crystal growth processes as closed tube vapor transport, open reactor vapor deposition, and the Czochralski and floating zone melt growth techniques, research results obtained to date are presented. It is noted that the major effort to date has been directed to the description of the nature and extent of bulk transport under realistic conditions, where bulk flow determines the heat and solute transport which strongly influence the temperature and concentration fields in the vicinity of the growth interface. Proper treatment of near field, or interface, problems cannot be given until the far field, or global flow, involved in a given crystal growth technique has been adequately described.

  12. 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.

  13. Otto Laporte Award Talk - In light of Fluid Mechanics

    NASA Astrophysics Data System (ADS)

    Gharib, Morteza

    2015-11-01

    Fluid mechanics, in its inherent non-linear beauty, has been its own laboratory, testing our perseverance and dedication to a branch of science that, despite its perceived maturity, still has many surprises to offer. For many of us, the study of fluid flow has been our path to understanding the complexity of nature. My journey has taken me through many interesting projects including the development of new visualization tools, scrutinizing the rhythms of the human heart, observing flow vortices and studying the dynamics of soap films. But this lecture is mainly devoted to a new example of my research activities where light and flow physics interweave to display another intriguing multi-physics beauty of nature.

  14. Valve operating mechanism for internal combustion engine

    SciTech Connect

    Fujii, N.; Iwata, T.; Takahara, N.

    1988-12-27

    This patent describes a valve operating mechanism in an internal combustion engine comprising: a single camshaft rotatably disposed above the cylinder head, a single rocker arm shaft rotatably disposed above the cylinder head; an intake-valve rocker arm swingably supported on the rocker arm shaft and operatively engaging the intake valve; an exhaust-valve rocker arm swingably supported on the rocker arm shaft and operatively engaging the exhaust valve, a camshaft holder disposed above the cylinder bore, the camshaft being rotatably supported by the camshaft holder; a rocker arms shaft holder disposed above the cylinder bore, the rocker arm shaft being rotatably supported by the rocker arm shaft holder; and a plug insertion tube having a plug insertion hole for insertion of the spark plug therethrough, the plug insertion tube being integrally formed with the camshaft holder and the rocker arm shaft holder in a holder block means.

  15. Phase optimized skeletal mechanisms for engine simulations

    NASA Astrophysics Data System (ADS)

    Blurock, Edward S.; Tuner, Martin; Mauss, Fabian

    2010-07-01

    Adaptive chemistry is based on the principle that instead of having one comprehensive model describing the entire range of chemical source term space (typically parameters related to temperature, pressure and species concentrations), a set of computationally simpler models are used, each describing a local region (in multidimensional space) or phases (in zero-dimensional space). In this work, an adaptive chemistry method based on phase optimized skeletal mechanisms (POSM) is applied to a 96 species n-heptane-isooctane mechanism within a two-zone zero-dimensional stochastic reactor model (SRM) for an spark-ignition (SI) Engine. Two models differing only in the extent of reduction in the phase mechanism, gave speed-up factors of 2.7 and 10. The novelty and emphasis of this study is the use of machine learning techniques to decide where the phases are and to produce a usable phase recognition. The combustion process is automatically divided up into an 'optimal' set of phases through machine learning clustering based on fuzzy logic predicates involving a necessity parameter (a measure giving an indication whether a species should be included in the mechanism or not). The mechanism of each phase is reduced from the full mechanism based on this necessity parameter with respect to the conditions of that phase. The algorithm to decide which phase the process is in is automatically determined by another machine learning method that produces decision trees. The decision tree is made up of asking whether the mass fraction values were above or below given values. Two POSM studies were done, a conservative POSM where the species in each phase are eliminated based on a necessity parameter threshold (speed-up 2.7) and a further reduced POSM where each phase was further reduced by hand (speed-up 10). The automated techniques of determining the phases and for creating the decision tree are very general and are not limited to the parameter choices of this paper. There is also no

  16. A general framework for robust control in fluid mechanics

    NASA Astrophysics Data System (ADS)

    Bewley, Thomas R.; Temam, Roger; Ziane, Mohammed

    2000-04-01

    The application of optimal control theory to complex problems in fluid mechanics has proven to be quite effective when complete state information from high-resolution numerical simulations is available [P. Moin, T.R. Bewley, Appl. Mech. Rev., Part 2 47 (6) (1994) S3-S13; T.R. Bewley, P. Moin, R. Temam, J. Fluid Mech. (1999), submitted for publication]. In this approach, an iterative optimization algorithm based on the repeated computation of an adjoint field is used to optimize the controls for finite-horizon nonlinear flow problems [F. Abergel, R. Temam, Theoret. Comput. Fluid Dyn. 1 (1990) 303-325]. In order to extend this infinite-dimensional optimization approach to control externally disturbed flows in which the controls must be determined based on limited noisy flow measurements alone, it is necessary that the controls computed be insensitive to both state disturbances and measurement noise. For this reason, robust control theory, a generalization of optimal control theory, has been examined as a technique by which effective control algorithms which are insensitive to a broad class of external disturbances may be developed for a wide variety of infinite-dimensional linear and nonlinear problems in fluid mechanics. An aim of the present paper is to put such algorithms into a rigorous mathematical framework, for it cannot be assumed at the outset that a solution to the infinite-dimensional robust control problem even exists. In this paper, conditions on the initial data, the parameters in the cost functional, and the regularity of the problem are established such that existence and uniqueness of the solution to the robust control problem can be proven. Both linear and nonlinear problems are treated, and the 2D and 3D nonlinear cases are treated separately in order to get the best possible estimates. Several generalizations are discussed and an appropriate numerical method is proposed.

  17. FRONT DETAIL OF RIGHT ENGINE AND WING. MECHANICS CHECK METAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    FRONT DETAIL OF RIGHT ENGINE AND WING. MECHANICS CHECK METAL CHIP DETECTOR ON RIGHT ENGINE. THE LEADING EDGE FLAPS ON THE RIGHT WING ARE DOWN PRIOR TO LUBRICATION. - Greater Buffalo International Airport, Maintenance Hangar, Buffalo, Erie County, NY

  18. ADDRESSING ENVIRONMENTAL ENGINEERING CHALLENGES WITH COMPUTATIONAL FLUID DYNAMICS

    EPA Science Inventory

    In the field of environmental engineering, modeling tools are playing an ever larger role in addressing air quality issues, including source pollutant emissions, atmospheric dispersion and human exposure risks. More detailed modeling of environmental flows requires tools for c...

  19. Power transmission mechanism equipped with fluid and centrifugal clutch

    SciTech Connect

    Tamura, K.; Takeshita, S.; Fukunaga, T.

    1986-12-30

    This patent describes a power transmission mechanism equipped with a fluid coupling, an input shaft thereof interconnected to a power source being interconnected through the fluid coupling to an output shaft, and the output shaft being interconnected to a forward-rearward changeover mechanism including a speed changer. It is characterized in that the fluid coupling includes a shell, an impeller in the shell and a centrifugal clutch means in the shell for engaging the impeller and for driving the impeller when the shell is rotated by the input shaft at a speed above idle speed and for disengaging the impeller and the driving of the impeller when the shell is rotated by the input shaft at the idle speed. A turbine is included in the shell for standing idle in the shell when the centrifugal clutch means is disengaged and for drive by the impeller when the centrifugal clutch means is engaged and for driving the output shaft. The centrifugal clutch means comprises a support member fixed to the shell, a centrifugal shoe mounted on the support member for radial movement outwardly of the support member by centrifugal force and radial movement inwardly toward the support member. It also comprises spring means for moving the shoe inwardly toward the support member when the shell is rotated at idle speed, a cylindrical casing fixed to the impeller radially outward from the shoe and having an engaging surface for engagement by the centrifugal shoe when the shell is rotated at a speed above idle speed and the centrifugal shoe is moved radially outward by centrifugal force. The forward-rearward changeover mechanism, including the speed changer, is driven by the turbine when the centrifugal clutch means is engaged with the engaging surface and standing idle when the centrifugal clutch means is disengaged from the engaging surface and the turbine is standing idle.

  20. The Fluid Mechanics of Cancer and Its Therapy

    NASA Astrophysics Data System (ADS)

    Koumoutsakos, Petros; Pivkin, Igor; Milde, Florian

    2013-01-01

    Fluid mechanics is involved in the growth, progression, metastasis, and therapy of cancer. Blood vessels transport oxygen and nutrients to cancerous tissues, provide a route for metastasizing cancer cells to distant organs, and deliver drugs to tumors. The irregular and leaky tumor vasculature is responsible for increased interstitial pressure in the tumor microenvironment, whereas multiscale flow-structure interaction processes control tumor growth, metastasis, and nanoparticle-mediated drug delivery. We outline these flow-mediated processes, along with related experimental and computational methods for the diagnosis, predictive modeling, and therapy of cancer.

  1. Review of coaxial flow gas core nuclear rocket fluid mechanics

    NASA Technical Reports Server (NTRS)

    Weinstein, H.

    1976-01-01

    Almost all of the fluid mechanics research associated with the coaxial flow gas core reactor ended abruptly with the interruption of NASA's space nuclear program because of policy and budgetary considerations in 1973. An overview of program accomplishments is presented through a review of the experiments conducted and the analyses performed. Areas are indicated where additional research is required for a fuller understanding of cavity flow and of the factors which influence cold and hot flow containment. A bibliography is included with graphic material.

  2. Partitioned fluid-solid coupling for cardiovascular blood flow: left-ventricular fluid mechanics.

    PubMed

    Krittian, Sebastian; Janoske, Uwe; Oertel, Herbert; Böhlke, Thomas

    2010-04-01

    We present a 3D code-coupling approach which has been specialized towards cardiovascular blood flow. For the first time, the prescribed geometry movement of the cardiovascular flow model KaHMo (Karlsruhe Heart Model) has been replaced by a myocardial composite model. Deformation is driven by fluid forces and myocardial response, i.e., both its contractile and constitutive behavior. Whereas the arbitrary Lagrangian-Eulerian formulation (ALE) of the Navier-Stokes equations is discretized by finite volumes (FVM), the solid mechanical finite elasticity equations are discretized by a finite element (FEM) approach. Taking advantage of specialized numerical solution strategies for non-matching fluid and solid domain meshes, an iterative data-exchange guarantees the interface equilibrium of the underlying governing equations. The focus of this work is on left-ventricular fluid-structure interaction based on patient-specific magnetic resonance imaging datasets. Multi-physical phenomena are described by temporal visualization and characteristic FSI numbers. The results gained show flow patterns that are in good agreement with previous observations. A deeper understanding of cavity deformation, blood flow, and their vital interaction can help to improve surgical treatment and clinical therapy planning.

  3. Biology: An Important Agricultural Engineering Mechanism

    ERIC Educational Resources Information Center

    Henderson, S. M.

    1974-01-01

    Describes the field of bioengineering with particular emphasis on agricultural engineering, and presents the results of a survey of schools that combine biology and engineering in their curricula. (JR)

  4. Role of cells in freezing-induced cell-fluid-matrix interactions within engineered tissues.

    PubMed

    Seawright, Angela; Ozcelikkale, Altug; Dutton, Craig; Han, Bumsoo

    2013-09-01

    During cryopreservation, ice forms in the extracellular space resulting in freezing-induced deformation of the tissue, which can be detrimental to the extracellular matrix (ECM) microstructure. Meanwhile, cells dehydrate through an osmotically driven process as the intracellular water is transported to the extracellular space, increasing the volume of fluid for freezing. Therefore, this study examines the effects of cellular presence on tissue deformation and investigates the significance of intracellular water transport and cell-ECM interactions in freezing-induced cell-fluid-matrix interactions. Freezing-induced deformation characteristics were examined through cell image deformetry (CID) measurements of collagenous engineered tissues embedded with different concentrations of MCF7 breast cancer cells versus microspheres as their osmotically inactive counterparts. Additionally, the development of a biophysical model relates the freezing-induced expansion of the tissue due to the cellular water transport and the extracellular freezing thermodynamics for further verification. The magnitude of the freezing-induced dilatation was found to be not affected by the cellular water transport for the cell concentrations considered; however, the deformation patterns for different cell concentrations were different suggesting that cell-matrix interactions may have an effect. It was, therefore, determined that intracellular water transport during freezing was insignificant at the current experimental cell concentrations; however, it may be significant at concentrations similar to native tissue. Finally, the cell-matrix interactions provided mechanical support on the ECM to minimize the expansion regions in the tissues during freezing.

  5. Marine Engine Mechanics. Performance Objectives. Intermediate Course.

    ERIC Educational Resources Information Center

    Jones, Marion

    Several intermediate performance objectives and corresponding criterion measures are presented for each of ten terminal objectives for a two-semester course (3 hours daily). This 540-hour intermediate course includes advanced troubleshooting techniques on outboard marine engines, inboard-outboard marine engines, inboard marine engines, boat…

  6. Performance Analysis of AN Engine Mount Featuring ER Fluids and Piezoactuators

    NASA Astrophysics Data System (ADS)

    Choi, S. H.; Choi, Y. T.; Choi, S. B.; Cheong, C. C.

    Conventional rubber mounts and various types of passive or semi-active hydraulic engine mounts for a passenger vehicle have their own functional aims on the limited frequency band in the broad engine operating frequency range. In order to achieve high system performance over all frequency ranges of the engine operation, a new type of engine mount featuring electro-rheological(ER) fluids and piezoactuators is proposed in this study. A mathematical model of the proposed engine mount is derived using the bond graph method which is inherently adequate to model the interconnected hydromechanical system. In the low frequency domain, the ER fluid is activated upon imposing an electric field for vibration isolation while the piezoactuator is activated in the high frequency domain. A neuro-control algorithm is utilized to determine control electric field for the ER fluid, and H∞ control technique is adopted for the piezoactuator Comparative works between the proposed and single-actuating(ER fluid only or piezoactuator only) engine mounts are undertaken by evaluating force transmissibility over a wide operating frequency range.

  7. Introducing CFD in Introductory Undergraduate Fluid Mechanics Courses

    NASA Astrophysics Data System (ADS)

    Cimbala, John M.

    2005-11-01

    Many instructors want to introduce CFD into their introductory junior-level fluid mechanics course, but cannot because it requires several hours of class time at the cost of displacement of other basic material. A simple but effective method is now available that has been used successfully at Penn State since Spring 2005. It requires minimal instructor preparation time and only about one class period. Namely, immediately after solving the Navier-Stokes equation analytically for simple flows such as Couette and Poiseuille flow, CFD is introduced as a modern tool for solving the same equations numerically. The application of CFD (grid generation, boundary conditions, etc.), rather than numerical algorithms, is stressed. Homework problems are then assigned using pre-defined templates for FlowLab, a student-friendly analysis and visualization package created by Fluent, Inc. The templates and exercises are designed to support and emphasize the theory and concepts taught in class and in the textbook. For example, the new textbook by Cengel and Cimbala (McGraw-Hill 2006) contains 46 end-of-chapter homework problems that are used in conjunction with 42 FlowLab templates. Each exercise has been designed with two major learning objectives in mind: (1) enhance student understanding of a specific fluid mechanics concept, and (2) introduce the student to a specific capability and/or limitation of CFD through hands-on practice.

  8. Respiratory mechanics and fluid dynamics after lung resection surgery.

    PubMed

    Miserocchi, Giuseppe; Beretta, Egidio; Rivolta, Ilaria

    2010-08-01

    Thoracic surgery that requires resection of a portion of lung or of a whole lung profoundly alters the mechanical and fluid dynamic setting of the lung-chest wall coupling, as well as the water balance in the pleural space and in the remaining lung. The most frequent postoperative complications are of a respiratory nature, and their incidence increases the more the preoperative respiratory condition seems compromised. There is an obvious need to identify risk factors concerning mainly the respiratory function, without neglecting the importance of other comorbidities, such as coronary disease. At present, however, a satisfactory predictor of postoperative cardiopulmonary complications is lacking; postoperative morbidity and mortality have remained unchanged in the last 10 years. The aim of this review is to provide a pathophysiologic interpretation of the main respiratory complications of a respiratory nature by relying on new concepts relating to lung fluid dynamics and mechanics. New parameters are proposed to improve evaluation of respiratory function from pre- to the early postoperative period when most of the complications occur.

  9. Competing disturbance amplification mechanisms in two-fluid boundary layers

    NASA Astrophysics Data System (ADS)

    Saha, Sandeep; Page, Jacob; Zaki, Tamer

    2015-11-01

    The linear stability of boundary layers above a thin wall film of lower viscosity is analyzed. Appropriate choice of the film thickness and viscosity excludes the possibility of interfacial instabilities. Transient amplification of disturbances is therefore the relevant destabilizing influence, and can take place via three different mechanisms in the two-fluid configuration. Each is examined in detail by solving an initial value problem whose initial condition comprises a pair of appropriately chosen eigenmodes from the discrete, continuous and interface modes. Two regimes are driven by the lift-up mechanism: (i) The response to a streamwise vortex and (ii) the normal vorticity generated by a stable Tollmien-Schlichting wave. Both are damped due to the film. The third regime is associated with the wall-normal vorticity that is generated by the interface displacement. It can lead to appreciable streamwise velocity disturbances in the near-wall region at relatively low viscosity ratios. The results demonstrate that a wall film can stabilize the early linear stages of boundary-layer transition, and explain the observations from the recent nonlinear direct numerical simulations of this configuration by Jung & Zaki (J. Fluid Mech., vol 772, 2015, 330-360).

  10. The role of computational fluid dynamics in aeronautical engineering

    NASA Astrophysics Data System (ADS)

    Kishimoto, Takuji; Uchida, Takashi

    1988-12-01

    Numerical analyses by solving Euler/Navier-Stokes Equations has been used in practical aeronautical engineerings. Here, the results of two dimensional Navier-Stokes analyses of a multiple slotted flap, and a three dimensional wing design problem using Euler analyses are shown.

  11. Trends in the Education and Training of Professional Mechanical Engineers.

    ERIC Educational Resources Information Center

    Institution of Mechanical Engineers, London (England).

    Twelve papers discussing problems encountered and solutions to them were presented at a symposium which brought together persons concerned with the training of professional mechanical engineers. At Session I, papers covered the need for broadly-based training and engineering practice, training requirements for engineers in the process industries,…

  12. [Present status and trend of heart fluid mechanics research based on medical image analysis].

    PubMed

    Gan, Jianhong; Yin, Lixue; Xie, Shenghua; Li, Wenhua; Lu, Jing; Luo, Anguo

    2014-06-01

    With introduction of current main methods for heart fluid mechanics researches, we studied the characteristics and weakness for three primary analysis methods based on magnetic resonance imaging, color Doppler ultrasound and grayscale ultrasound image, respectively. It is pointed out that particle image velocity (PIV), speckle tracking and block match have the same nature, and three algorithms all adopt block correlation. The further analysis shows that, with the development of information technology and sensor, the research for cardiac function and fluid mechanics will focus on energy transfer process of heart fluid, characteristics of Chamber wall related to blood fluid and Fluid-structure interaction in the future heart fluid mechanics fields.

  13. Serious Fun: Using Toys to Demonstrate Fluid Mechanics Principles

    ERIC Educational Resources Information Center

    Saviz, Camilla M.; Shakerin, Said

    2014-01-01

    Many students have owned or seen fluids toys in which two immiscible fluids within a closed container can be tilted to generate waves. These types of inexpensive and readily available toys are fun to play with, but they are also useful for provoking student learning about fluid properties or complex fluid behavior, including drop formation and…

  14. Mechanical properties of natural cartilage and tissue-engineered constructs.

    PubMed

    Little, Christopher James; Bawolin, Nahshon Kenneth; Chen, Xiongbiao

    2011-08-01

    There has been much research over the past two decades with the aim of engineering cartilage constructs for repairing or restoring damaged cartilage. To engineer healthy neocartilage, the constructs must have mechanical properties matching those of native cartilage as well as appropriate for the loading conditions of the joint. This article discusses the mechanical behavior of native cartilage and surveys different types of tensile, compressive, and shear tests with their limitations. It also comprehensively reviews recent work and achievements in developing the mathematical models representing the mechanical properties of both native and engineered cartilage. Different methods for enhancing the mechanical properties of engineered cartilage are also discussed, including scaffold design, mechanical stimulation, and chemical stimulation. This article concludes with recommendations for future research aimed at achieving engineered cartilage with mechanical properties matching those found in native cartilage.

  15. Computational thermal, chemical, fluid, and solid mechanics for geosystems management.

    SciTech Connect

    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.

  16. Passive mechanical behavior of human neutrophils: power-law fluid.

    PubMed Central

    Tsai, M A; Frank, R S; Waugh, R E

    1993-01-01

    = 130 +/- 23 Pa.s and b = 0.52 +/- 0.09 for normal neutrophils. The power-law approximation has a remarkable ability to reconcile discrepancies among published values of the cytoplasmic viscosity measured using different techniques, even though these values differ by nearly two orders of magnitude. Thus, the power-law fluid model is a promising candidate for describing the passive mechanical behavior of human neutrophils in large deformation. It can also account for some discrepancies between cellular behavior in single-cell micromechanical experiments and predictions based on the assumption that the cytoplasm is a simple Newtonian fluid. Images FIGURE 1 FIGURE 4 PMID:8298037

  17. Links between fluid mechanics and quantum mechanics: a model for information in economics?

    PubMed

    Haven, Emmanuel

    2016-05-28

    This paper tallies the links between fluid mechanics and quantum mechanics, and attempts to show whether those links can aid in beginning to build a formal template which is usable in economics models where time is (a)symmetric and memory is absent or present. An objective of this paper is to contemplate whether those formalisms can allow us to model information in economics in a novel way.

  18. Wentworth Institute Mechanical Engineering Laboratory Manual. Laboratory Study Guide.

    ERIC Educational Resources Information Center

    Avakian, Harry; And Others

    This publication is a laboratory study guide designed for mechanical engineering students. All of the experiments (with the exception of experiment No. 1) contained in the Mechanical Engineering Laboratory Manual have been included in this guide. Brief theoretical backgrounds, examples and their solutions, charts, graphs, illustrations, and…

  19. 2. Photographic copy of engineering drawing showing mechanical systems in ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. Photographic copy of engineering drawing showing mechanical systems in plan and sections of Test Stand 'E,' including tunnel entrance. California Institute of Technology, Jet Propulsion Laboratory, Plant Engineering 'Bldg. E-60 Mechanical, Solid Propellant Test Stand,' sheet E60/13-4, June 20, 1961. - Jet Propulsion Laboratory Edwards Facility, Test Stand E, Edwards Air Force Base, Boron, Kern County, CA

  20. Statistical mechanical description of supercritical fluid extraction and retrograde condensation

    NASA Astrophysics Data System (ADS)

    Park, S. J.; Kwak, T. Y.; Mansoori, G. A.

    1987-07-01

    The phenomena of supercritical fluid extraction (SFE) and its reverse effect, which is known as retrograde condensation (RC), have found new and important applications in industrial separation of chemical compounds and recovery and processing of natural products and fossil fuels. Full-scale industrial utilization of SFE/RC processes requires knowledge about thermodynamic and transport characteristics of the asymmetric mixtures involved and the development of predictive modeling and correlation techniques for performance of the SFE/RC system under consideration. In this report, through the application of statistical mechanical techniques, the reasons for the lack of accuracy of existing predictive approaches are described and they are improved. It is demonstrated that these techniques also allow us to study the effect of mixed supercritical solvents on the solubility of heavy solutes (solids) at different compositions of the solvents, pressures, and temperatures. Fluid phase equilibrium algorithms based on the conformal solution van der Waals mixing rules and different equations of state are presented for the prediction of solubilities of heavy liquid in supercritical gases. It is shown that the Peng-Robinson equation of state based on conformal solution theory can predict solubilites of heavy liquid in supercritical gases more accurately than the van der Waals and Redlich-Kwong equations of state.

  1. Fluid mechanics of biological surfaces and their technological application.

    PubMed

    Bechert, D W; Bruse, M; Hage, W; Meyer, R

    2000-04-01

    A survey is given on fluid-dynamic effects caused by the structure and properties of biological surfaces. It is demonstrated that the results of investigations aiming at technological applications can also provide insights into biophysical phenomena. Techniques are described both for reducing wall shear stresses and for controlling boundary-layer separation. (a) Wall shear stress reduction was investigated experimentally for various riblet surfaces including a shark skin replica. The latter consists of 800 plastic model scales with compliant anchoring. Hairy surfaces are also considered, and surfaces in which the no-slip condition is modified. Self-cleaning surfaces such as that of lotus leaves represent an interesting option to avoid fluid-dynamic deterioration by the agglomeration of dirt. An example of technological implementation is discussed for riblets in long-range commercial aircraft. (b) Separation control is also an important issue in biology. After a few brief comments on vortex generators, the mechanism of separation control by bird feathers is described in detail. Self-activated movable flaps (= artificial bird feathers) represent a high-lift system enhancing the maximum lift of airfoils by about 20%. This is achieved without perceivable deleterious effects under cruise conditions. Finally, flight experiments on an aircraft with laminar wing and movable flaps are presented.

  2. Mechanical Engineering Education and Its Challenges

    NASA Astrophysics Data System (ADS)

    Ow, C. S.; Kanan, M. M.

    2015-09-01

    The paper addresses historical development in Engineering Education in the country, its evolution till present day efforts toward the formation of Professional Engineers (PE). Of particular interest is the proposed recognition of more than one pathways towards PE Certification amongst member countries of the International Engineering Alliance (IEA). However, Engineering Education of Gen Y poses challenges at maintaining relevant benchmarks at the basic degree level. The widespread use of sophisticated software for simulation work in any undergraduate programme has its sacrifices with respect to emphasis on depth of knowledge. A definite mismatch between what is perceived by the educators and the actual performance of graduates had been identified in a forum and an employment survey conducted by the Institution of Engineers Malaysia (IEM). Suggestions as to how this can be addressed include the setting up of a Board of Educators to regulate the education industry.

  3. Development of a rotary fluid transfer coupling and support mechanism for space station

    NASA Technical Reports Server (NTRS)

    Bradley, O. H., Jr.; Costulis, J. A.; Porter, A. H.

    1988-01-01

    A design was developed for a rotary fluid coupling to transfer coolant fluids (primarily anhydrous ammonia) across rotating joints of the space station. Development testing using three conceptual designs yielded data which were used to establish the design of a multipass fluid coupling capable of handling three fluid circuits. In addition, a mechanism to support the fluid coupling and allow an astronaut to replace the coupling quickly and easily was designed.

  4. Shift mechanism for engine starting apparatus

    SciTech Connect

    Colvin, J.A.; Colvill, R.G.; Smock, A.L.

    1986-04-01

    This patent describes a shift lever mechanism for translating axial movement of the plunger of a starter solenoid into axial movement of a pinion of an engine starting apparatus. This apparatus consists of, a starter solenoid having an axially shiftable plunger and a coil winding, a spring opposing pull-in movement of the plunger and a solenoid switch operated to a closed condition when the plunger is completely pulled-in, a shift lever actuator carried by the plunger for axial movement therewith. The actuator has a pair of spaced surfaces, a pivotally mounted shift lever one end of which is adapted to be coupled to the pinion. The opposite end of the shift lever has a pair of opposed shift lever surfaces that respectively engage the surfaces on the actuator. The actuator surfaces and the shift lever surfaces are substantially engaged when the shift lever is in an at rest postion. The surfaces on the shift lever are at different radial distances from the pivot point of the shift lever and are arranged relative to the surfaces on the actuator such that when the solenoid plunger pulls-in the surface on the shift lever that is at the greater radial distance from the pivot point is moved by a surface of the actuator and the other surface on the shift lever becomes separated by a predetermined amount from its cooperating surface on the actuator. The amount of separation is sufficient to allow the solenoid switch to be actuated to an open condition when the solenoid coil winding is deenergized and the spring shifts and plunger to reengage the separated surfaces.

  5. Fluid mechanics relevant to flow through pretreatment of cellulosic biomass.

    PubMed

    Archambault-Léger, Véronique; Lynd, Lee R

    2014-04-01

    The present study investigates fluid mechanical properties of cellulosic feedstocks relevant to flow through (FT) pretreatment for biological conversion of cellulosic biomass. The results inform identifying conditions for which FT pretreatment can be implemented in a practical context. Measurements of pressure drop across packed beds, viscous compaction and water absorption are reported for milled and not milled sugarcane bagasse, switchgrass and poplar, and important factors impacting viscous flow are deduced. Using biomass knife-milled to pass through a 2mm sieve, the observed pressure drop was highest for bagasse, intermediate for switchgrass and lowest for poplar. The highest pressure drop was associated with the presence of more fine particles, greater viscous compaction and the degree of water absorption. Using bagasse without particle size reduction, the instability of the reactor during pretreatment above 140kg/m(3) sets an upper bound on the allowable concentration for continuous stable flow.

  6. An explicit example of Hopf bifurcation in fluid mechanics

    NASA Technical Reports Server (NTRS)

    Kloeden, P.; Wells, R.

    1983-01-01

    It is observed that a complete and explicit example of Hopf bifurcation appears not to be known in fluid mechanics. Such an example is presented for the rotating Benard problem with free boundary conditions on the upper and lower faces, and horizontally periodic solutions. Normal modes are found for the linearization, and the Veronis computation of the wave numbers is modified to take into account the imposed horizontal periodicity. An invariant subspace of the phase space is found in which the hypotheses of the Joseph-Sattinger theorem are verified, thus demonstrating the Hopf bifurcation. The criticality calculations are carried through to demonstrate rigorously, that the bifurcation is subcritical for certain cases, and to demonstrate numerically that it is subcritical for all the cases in the paper.

  7. An intelligent data acquisition system for fluid mechanics research

    NASA Technical Reports Server (NTRS)

    Cantwell, E. R.; Zilliac, G.; Fukunishi, Y.

    1989-01-01

    This paper describes a novel data acquisition system for use with wind-tunnel probe-based measurements, which incorporates a degree of specific fluid dynamics knowledge into a simple expert system-like control program. The concept was developed with a rudimentary expert system coupled to a probe positioning mechanism operating in a small-scale research wind tunnel. The software consisted of two basic elements, a general-purpose data acquisition system and the rulebased control element to take and analyze data and supplying decisions as to where to measure, how many data points to take, and when to stop. The system was validated in an experiment involving a vortical flow field, showing that it was possible to increase the resolution of the experiment or, alternatively, reduce the total number of data points required, to achieve parity with the results of most conventional data acquisition approaches.

  8. Elliptic Functions and Integrals with Real Modulus in Fluid Mechanics

    NASA Technical Reports Server (NTRS)

    Legendre, Robert

    1958-01-01

    Advantage of the elliptic functions and of the more general functions of Schwarz for fluid mechanics. Flows outside and inside polygons. Application to the calculation of an elbow diffuser for a wind tunnel. Properties of the elliptic integrals of the first kind and of the elliptic functions. Properties of the theta functions and decomposition of the elliptic functions into products of theta functions. Properties of the zeta functions. Decomposition of the elliptic functions into sums of zeta functions and calculations of the elliptic integrals. Applications to the calculation of wing profiles, of compressor profiles, and to the study of the vibrations of airplane wings and of compressor vanes. The manuscript of the present paper was checked by Mr. Eichelbrenner who corrected several imperfections and suggested numerous improvements to make reading of the paper easier. However, the limited subject does not permit filling in more than an incomplete knowledge of the properties of analytic functions.

  9. A cubic spline approximation for problems in fluid mechanics

    NASA Technical Reports Server (NTRS)

    Rubin, S. G.; Graves, R. A., Jr.

    1975-01-01

    A cubic spline approximation is presented which is suited for many fluid-mechanics problems. This procedure provides a high degree of accuracy, even with a nonuniform mesh, and leads to an accurate treatment of derivative boundary conditions. The truncation errors and stability limitations of several implicit and explicit integration schemes are presented. For two-dimensional flows, a spline-alternating-direction-implicit method is evaluated. The spline procedure is assessed, and results are presented for the one-dimensional nonlinear Burgers' equation, as well as the two-dimensional diffusion equation and the vorticity-stream function system describing the viscous flow in a driven cavity. Comparisons are made with analytic solutions for the first two problems and with finite-difference calculations for the cavity flow.

  10. Fluid mechanical model of the acoustic impedance of small orifices

    NASA Technical Reports Server (NTRS)

    Hersh, A. S.; Rogers, T.

    1976-01-01

    A fluid mechanical model of the acoustic behavior of small orifices is presented which predicts orifice resistance and reactance as a function of incident sound pressure level, frequency, and orifice geometry. Agreement between predicted and measured values is excellent. The model shows the following: (1) The acoustic flow in immediate neighborhood of the orifice can be modeled as a locally spherical flow. Within this near field, the flow is, to a first approximation, unsteady and incompressible. (2) At very low sound pressure levels, the orifice viscous resistance is directly related to the effect of boundary-layer displacement along the walls containing the orifice, and the orifice reactance is directly related to the inertia of the oscillating flow in the neighborhood of the orifice. (3) For large values of the incident acoustic pressure, the impedance is dominated by nonlinear jet-like effects. (4) For low values of the pressure, the resistance and reactance are roughly equal.

  11. Combustion research in the Internal Fluid Mechanics Division

    NASA Technical Reports Server (NTRS)

    Mularz, Edward J.

    1986-01-01

    The goal of this research is to bring computational fluid dynamics to a state of practical application for the aircraft engine industry. The approach is to have a strongly integrated computational and experimental program for all the disciplines associated with the gas turbine and other aeropropulsion systems by advancing the understanding of flow physics, heat transfer, and combustion processes. The computational and experimental research is integrated in the following way: the experiments that are performed provide an empirical data set so that physical models can be formulated to describe the processes that are occurring - for example, turbulence or chemical reaction. These experiments also form a data base for those who are doing code development by providing experimental data against which the codes can be verified and assesed. Models are generated as closure to some of the numerical codes, and they also provide physical insight for experiments. At the same time, codes which solve the complete Navier-Stokes equations can be used as a kind of numerical experiment from which far more extensive data can be obtained than ever could be obtained experimentally. This could provide physical insight into the complex processes that are taking place. These codes are also exercised against experimental data to assess the accuracy and applicability of models.

  12. Introduction to the internal fluid mechanics research session

    NASA Technical Reports Server (NTRS)

    Miller, Brent A.; Povinelli, Louis A.

    1990-01-01

    Internal fluid mechanics research at LeRC is directed toward an improved understanding of the important flow physics affecting aerospace propulsion systems, and applying this improved understanding to formulate accurate predictive codes. To this end, research is conducted involving detailed experimentation and analysis. The following three papers summarize ongoing work and indicate future emphasis in three major research thrusts: inlets, ducts, and nozzles; turbomachinery; and chemical reacting flows. The underlying goal of the research in each of these areas is to bring internal computational fluid mechanic to a state of practical application for aerospace propulsion systems. Achievement of this goal requires that carefully planned and executed experiments be conducted in order to develop and validate useful codes. It is critical that numerical code development work and experimental work be closely coupled. The insights gained are represented by mathematical models that form the basis for code development. The resultant codes are then tested by comparing them with appropriate experiments in order to ensure their validity and determine their applicable range. The ultimate user community must be a part of this process to assure relevancy of the work and to hasten its practical application. Propulsion systems are characterized by highly complex and dynamic internal flows. Many complex, 3-D flow phenomena may be present, including unsteadiness, shocks, and chemical reactions. By focusing on specific portions of a propulsion system, it is often possible to identify the dominant phenomena that must be understood and modeled for obtaining accurate predictive capability. The three major research thrusts serve as a focus leading to greater understanding of the relevant physics and to an improvement in analytic tools. This in turn will hasten continued advancements in propulsion system performance and capability.

  13. Effect of fluid medium on mechanical behavior of carbon nanotube foam

    NASA Astrophysics Data System (ADS)

    Misra, Abha; Kumar, Praveen; Raney, Jordan R.; Singhal, Anish; Lattanzi, Ludovica; Daraio, Chiara

    2014-06-01

    This study reports the constitutive response and energy absorption capabilities of fluid-impregnated carbon nanotube (CNT) foams under compressive loading as a function of fluid viscosity and loading rates. At all strain rates tested, we observe two characteristic regimes: below a critical value, increasing fluid viscosity increases the load bearing and energy absorption capacities; after a critical value of the fluid's viscosity, we observe a rapid decrease in the systems' mechanical performance. For a given fluid viscosity, the load bearing capacity of the structure slightly decreases with strain rate. A phenomenological model, accounting for fluid-CNT interaction, is developed to explain the observed mechanical behavior.

  14. Fast Prediction of HCCI Combustion with an Artificial Neural Network Linked to a Fluid Mechanics Code

    SciTech Connect

    Aceves, S M; Flowers, D L; Chen, J; Babaimopoulos, A

    2006-08-29

    We have developed an artificial neural network (ANN) based combustion model and have integrated it into a fluid mechanics code (KIVA3V) to produce a new analysis tool (titled KIVA3V-ANN) that can yield accurate HCCI predictions at very low computational cost. The neural network predicts ignition delay as a function of operating parameters (temperature, pressure, equivalence ratio and residual gas fraction). KIVA3V-ANN keeps track of the time history of the ignition delay during the engine cycle to evaluate the ignition integral and predict ignition for each computational cell. After a cell ignites, chemistry becomes active, and a two-step chemical kinetic mechanism predicts composition and heat generation in the ignited cells. KIVA3V-ANN has been validated by comparison with isooctane HCCI experiments in two different engines. The neural network provides reasonable predictions for HCCI combustion and emissions that, although typically not as good as obtained with the more physically representative multi-zone model, are obtained at a much reduced computational cost. KIVA3V-ANN can perform reasonably accurate HCCI calculations while requiring only 10% more computational effort than a motored KIVA3V run. It is therefore considered a valuable tool for evaluation of engine maps or other performance analysis tasks requiring multiple individual runs.

  15. Remaining useful life measurements of diesel engine oils, automotive engine oils, hydraulic fluids, and greases using cyclic voltammetric methods

    SciTech Connect

    Kauffman, R.E.

    1995-03-01

    This paper presents the results of research designed to develop a remaining useful life evaluation rig (RULER) from cyclic voltammetric methods for diesel engine oils, automotive engine oils, hydraulic fluids, and greases. The RULER requires less than one millimeter of sample, less than one minute to perform, and very little technical expertise. Samples of laboratory-stressed and authentic-used oils, fluids, and greases were used in the development of the RULER. The results of this research demonstrate that remaining useful life measurements made by the RULER can be used by oil analysis programs to quantify antioxidant levels of incoming and stored supplies, to predict and extend oil change intervals for normally operating equipment, and to detect abnormally operating equipment prior to malfunction. 13 refs., 8 figs.

  16. A systems approach to theoretical fluid mechanics: Fundamentals

    NASA Technical Reports Server (NTRS)

    Anyiwo, J. C.

    1978-01-01

    A preliminary application of the underlying principles of the investigator's general system theory to the description and analyses of the fluid flow system is presented. An attempt is made to establish practical models, or elements of the general fluid flow system from the point of view of the general system theory fundamental principles. Results obtained are applied to a simple experimental fluid flow system, as test case, with particular emphasis on the understanding of fluid flow instability, transition and turbulence.

  17. A brief tour of the climate machine. 1 - The Climate machine, a two fluids thermal engine

    NASA Astrophysics Data System (ADS)

    Poitou, Jean

    2017-03-01

    The climate machine is a thermal engine that gets all its heat from the sun and redistributes it on the Earth surface through coupled fluid circulation of the atmosphere and the ocean. Water present on Earth in its three physical states — solid, liquid and gas — plays a key role in the climate.

  18. Development of Engineering Design Education in the Department of Mechanical Engineering at Kanazawa Technical College

    NASA Astrophysics Data System (ADS)

    Yamada, Hirofumi; Ten-Nichi, Michio; Mathui, Hirosi; Nakamura, Akizi

    This paper introduces a method of the engineering design education for college of technology mechanical engineering students. In order to teach the practical engineering design, the MIL-STD-499A process is adapted and improved upon for a Mechatronics hands-on lesson used as the MOT method. The educational results in five years indicate that knowledge of the engineering management is useful for college students in learning engineering design. Portfolio for lessons and the hypothesis method also have better effects on the understanding of the engineering specialty.

  19. Ups and downs of using ``kitchen sink'' experiments in an introductory fluid mechanics class

    NASA Astrophysics Data System (ADS)

    Kaye, Nigel

    2015-11-01

    Both positive and negative experiences from two semesters of using take home ``kitchen sink'' experiments in an introductory civil engineering fluid mechanics class are reported. Four different experimental assignments were given each semester to groups of four students. The students were tasked with using common household equipment to measure various properties of fluids or fluid flows. These included the density of cooking oil, the exit velocity from a garden hose, and the mass flux of air from a compressed air can. Students were given minimal guidance on how to do the measurements and each measurement had to be done in at least two different ways. The labs were used to relate their course work to everyday situations and was also used as a platform for discussing experimental uncertainty and error propagation in calculations. In general the students successfully completed each task using at least one method. Finding a second method sometimes proved problematic. The presentation will discuss the logistics of running the program and the positive and negative aspects from the instructor viewpoint. A summary of student feedback on the labs will also be presented. Links to resources for those interested in implementing such a program will be provided.

  20. Fluid dynamic mechanisms and interactions within separated flows

    NASA Astrophysics Data System (ADS)

    Dutton, J. C.; Addy, A. L.

    1990-02-01

    The significant results of a joint research effort investigating the fundamental fluid dynamic mechanisms and interactions within high-speed separated flows are presented in detail. The results have obtained through analytical and numerical approaches, but with primary emphasis on experimental investigations of missile and projectile base flow-related configurations. The objectives of the research program focus on understanding the component mechanisms and interactions which establish and maintain high-speed separated flow regions. The analytical and numerical efforts have centered on unsteady plume-wall interactions in rocket launch tubes and on predictions of the effects of base bleed on transonic and supersonic base flowfields. The experimental efforts have considered the development and use of a state-of-the-art two component laser Doppler velocimeter (LDV) system for experiments with planar, two-dimensional, small-scale models in supersonic flows. The LDV experiments have yielded high quality, well documented mean and turbulence velocity data for a variety of high-speed separated flows including initial shear layer development, recompression/reattachment processes for two supersonic shear layers, oblique shock wave/turbulent boundary layer interactions in a compression corner, and two-stream, supersonic, near-wake flow behind a finite-thickness base.

  1. Computational fluid dynamics applied to flows in an internal combustion engine

    NASA Technical Reports Server (NTRS)

    Griffin, M. D.; Diwakar, R.; Anderson, J. D., Jr.; Jones, E.

    1978-01-01

    The reported investigation is a continuation of studies conducted by Diwakar et al. (1976) and Griffin et al. (1976), who reported the first computational fluid dynamic results for the two-dimensional flowfield for all four strokes of a reciprocating internal combustion (IC) engine cycle. An analysis of rectangular and cylindrical three-dimensional engine models is performed. The working fluid is assumed to be inviscid air of constant specific heats. Calculations are carried out of a four-stroke IC engine flowfield wherein detailed finite-rate chemical combustion of a gasoline-air mixture is included. The calculations remain basically inviscid, except that in some instances thermal conduction is included to allow a more realistic model of the localized sparking of the mixture. All the results of the investigation are obtained by means of an explicity time-dependent finite-difference technique, using a high-speed digital computer.

  2. Hydraulic fluids and jet engine oil: pyrolysis and aircraft air quality.

    PubMed

    van Netten, C; Leung, V

    2001-01-01

    Incidents of smoke in aircraft cabins often result from jet engine oil and/or hydraulic fluid that leaks into ventilation air, which can be subjected to temperatures that exceed 500 degrees C. Exposed flight-crew members have reported symptoms, including dizziness, nausea, disorientation, blurred vision, and tingling in the legs and arms. In this study, the authors investigated pyrolysis products of one jet engine oil and two hydraulic fluids at 525 degrees C. Engine oil was an important source of carbon monoxide. Volatile agents and organophosphate constituents were released from all the agents tested; however, the neurotoxin trimethyl propane phosphate was not found. The authors hypothesized that localized condensation of pyrolysis products in ventilation ducts, followed by mobilization when cabin heat demand was high, accounted for mid-flight incidents. The authors recommended that carbon monoxide data be logged continuously to capture levels during future incidents.

  3. Fundamental Studies of Fluid Mechanics: Stability in Porous Media

    SciTech Connect

    George M. Homsy

    2005-04-28

    This work has been concerned with theoretical, computational and experimental studies of a variety of flow and transport problems that are of generic interest and applicability in energy-related and energy-intensive processes. These include the following. (1) Problems associated with oil recovery: the global economy continues to be dependent on the stable and predictable supply of oil and fossil fuels. This will remain the case for the near term, as current estimates are that world production of oil will peak between 2025 and 2100, depending on assumptions regarding growth. Most of these resources reside in porous rocks and other naturally occurring media. Studies of flow-induced instabilities are relevant to the areas of secondary and enhanced oil recovery. (2) Small scale and Stokes flows: flows in microgeometries and involving interfaces and surfactants are of interest in a myriad of energy-related contexts. These include: pore-level modeling of the fundamental processes by which oil held in porous materials is mobilized and produced; heating and cooling energy cycles involving significant expenditure of energy in conditioning of human environments, heat pipes, and compact heat exchangers; and energy efficiency in large scale separation processes such as distillation and absorption-processes that underlie the chemical process industries. (3) Coating flows: these are of interest in information technologies, including the manufacture of integrated circuits and data storage and retrieval devices. It is estimated that 50-70% of the starting raw materials and intermediate devices in information technology processes must be discarded as a result of imperfections and failure to meet specifications. These in turn are often the result of the inability to control fluid-mechanical processes and flow instabilities. Our work over the grant period is primarily fundamental in nature. We are interested in establishing general principles and behaviors that relate to a variety of

  4. Marine Engine Mechanics. Performance Objectives. Basic Course.

    ERIC Educational Resources Information Center

    Jones, Marion

    Several intermediate performance objectives and corresponding criterion measures are presented for each of six terminal objectives for a two-semester course (2 hours daily) which provides training in the terminology, construction, and function of both two- and four-cycle fuel-air mixture internal combustion engines with emphasis on outboard marine…

  5. Mechanical fuel injector for internal combustion engines

    SciTech Connect

    Beaty, K.D.

    1993-08-31

    An apparatus is described for injecting fuel into an internal combustion engine having an air inlet containing an adjustable air throttle valve, comprising: a hollow injector body having a cylindrical bore therein; a compression head closing one end of the bore; a pump head closing an opposite end of the bore; a plunger piston reciprocally moveable within the cylinder bore defining a variable volume fuel pumping chamber formed by the injector body, the compression head, and a first end of the piston, and a variable volume compression chamber formed by the injector body, the pump head and a second end of the piston; fuel supply means connected to the pumping chamber; fuel passage means interconnecting the pumping chamber, the compression chamber and the fuel supply means; air supply means connected to the fuel passage means; fuel/air discharge means connected to the compression chamber; an injection nozzle located in the engine and connected to the fuel/air discharge means for injecting a mixture of fuel and air into the engine for combustion therein; and actuator means operably interconnecting the piston and the engine for reciprocating the piston within the cylinder bore of the injector body.

  6. Mathematical Building-Blocks in Engineering Mechanics

    ERIC Educational Resources Information Center

    Boyajian, David M.

    2007-01-01

    A gamut of mathematical subjects and concepts are taught within a handful of courses formally required of the typical engineering student who so often questions the relevancy of being bound to certain lower-division prerequisites. Basic classes at the undergraduate level, in this context, include: Integral and Differential Calculus, Differential…

  7. Statistical mechanics of homogeneous partly pinned fluid systems.

    PubMed

    Krakoviack, Vincent

    2010-12-01

    The homogeneous partly pinned fluid systems are simple models of a fluid confined in a disordered porous matrix obtained by arresting randomly chosen particles in a one-component bulk fluid or one of the two components of a binary mixture. In this paper, their configurational properties are investigated. It is shown that a peculiar complementarity exists between the mobile and immobile phases, which originates from the fact that the solid is prepared in presence of and in equilibrium with the adsorbed fluid. Simple identities follow, which connect different types of configurational averages, either relative to the fluid-matrix system or to the bulk fluid from which it is prepared. Crucial simplifications result for the computation of important structural quantities, both in computer simulations and in theoretical approaches. Finally, possible applications of the model in the field of dynamics in confinement or in strongly asymmetric mixtures are suggested.

  8. Introducing Non-Newtonian Fluid Mechanics Computations with Mathematica in the Undergraduate Curriculum

    ERIC Educational Resources Information Center

    Binous, Housam

    2007-01-01

    We study four non-Newtonian fluid mechanics problems using Mathematica[R]. Constitutive equations describing the behavior of power-law, Bingham and Carreau models are recalled. The velocity profile is obtained for the horizontal flow of power-law fluids in pipes and annuli. For the vertical laminar film flow of a Bingham fluid we determine the…

  9. Hydrodynamic parameters modulate biochemical, histological, and mechanical properties of engineered cartilage.

    PubMed

    Bueno, Ericka M; Bilgen, Bahar; Barabino, Gilda A

    2009-04-01

    Functional engineered cartilage constructs represent a promising therapeutic approach for the replacement of damaged articular cartilage. The in vitro generation of cartilage tissue suitable for repair requires an understanding of the complex interrelationships between environmental cues, such as hydrodynamic forces, and tissue growth and development. In the present study, engineered cartilage constructs were cultivated in four well-defined hydrodynamic environments within a bioreactor, and correlations were established between construct ultrastructural and mechanical properties and key hydrodynamic parameters. Results suggest that even for similar composition, constructs may exhibit different mechanical properties due to differences in their ultrastructure that can be modulated by hydrodynamic parameters. For example, improved mechanical properties were observed in constructs that exhibited a thick fibrous outer capsule as a result of cultivation under increased hydrodynamic shear. In particular, uniformity in the contribution of the fluid velocity vectors (axial, radial, and tangential) to the total fluid velocity and shear stress were the hydrodynamic parameters that most affected the construct properties under investigation. The correlations identified here may be useful in the development of engineered tissue growth models that inform the design of bioreactor cultivation systems toward the production of clinically relevant engineered cartilage.

  10. Computational estimation of fluid mechanical benefits from a fluid deflector at the distal end of artificial vascular grafts.

    PubMed

    Roos, M W; Wadbro, E; Berggren, M

    2013-02-01

    Intimal hyperplasia at the distal anastomosis is considered to be an important determinant for arterial and arteriovenous graft failure. The connection between unhealthy hemodynamics and intimal hyperplasia motivates the use of computational fluid dynamics modeling to search for improved graft design. However, studies on the fluid mechanical impact on intimal hyperplasia at the suture line intrusion have previously been scanty. In the present work, we focus on intimal hyperplasia at the suture line and illustrate potential benefits from the introduction of a fluid deflector to shield the suture line from unhealthily high wall shear stress.

  11. Multidimensional Generalized Functions in Aeroacoustics and Fluid Mechanics. Part 1; Basic Concepts and Operations

    NASA Technical Reports Server (NTRS)

    Farassat, Fereidoun; Myers, Michael K.

    2011-01-01

    This paper is the first part of a three part tutorial on multidimensional generalized functions (GFs) and their applications in aeroacoustics and fluid mechanics. The subject is highly fascinating and essential in many areas of science and, in particular, wave propagation problems. In this tutorial, we strive to present rigorously and clearly the basic concepts and the tools that are needed to use GFs in applications effectively and with ease. We give many examples to help the readers in understanding the mathematical ideas presented here. The first part of the tutorial is on the basic concepts of GFs. Here we define GFs, their properties and some common operations on them. We define the important concept of generalized differentiation and then give some interesting elementary and advanced examples on Green's functions and wave propagation problems. Here, the analytic power of GFs in applications is demonstrated with ease and elegance. Part 2 of this tutorial is on the diverse applications of generalized derivatives (GDs). Part 3 is on generalized Fourier transformations and some more advanced topics. One goal of writing this tutorial is to convince readers that, because of their powerful operational properties, GFs are absolutely essential and useful in engineering and physics, particularly in aeroacoustics and fluid mechanics.

  12. Formula Student as Part of a Mechanical Engineering Curriculum

    ERIC Educational Resources Information Center

    Davies, Huw Charles

    2013-01-01

    Formula Student (FS) is a multi-university student design competition managed by the UK Institution of Mechanical Engineers. Students are required to demonstrate and prove their creativity and engineering skills through the design, manufacture and financing of a small formula style race car. This paper seeks to explore the educational value that…

  13. Fluid Shearing for Accelerated Chemical Reactions - Fluid Mechanics in the VFD

    NASA Astrophysics Data System (ADS)

    Leivadarou, Evgenia; Dalziel, Stuart; G. K. Batchelor Laboratory, Department of Applied Mathematics; Theoretical Physics Team

    2016-11-01

    The Vortex Fluidic Device (VFD) is a rapidly rotating tube that can operate under continuous flow with a jet feeding liquid reactants to the tube's hemispherical base. It is a new 'green' approach to the organic synthesis with many industrial applications in cosmetics, protein folding and pharmaceutical production. The rate of reaction in the VFD is enhanced when the collision rate is increased. The aim of the project is to explain the fluid mechanics and optimize the performance of the device. One contribution to the increased yield is believed to be the high levels of shear stress. We attempt to enhance the shear stress by achieving high velocity gradients in the boundary layers. Another factor is the uncontrolled vibrations due to imperfections in the bearings and therefore it is important to assess their influence in the initial spreading. The surface area of the film should be maximized with respect to the rotation rate, geometry and orientation of the tube, flow rate, wettability and contact line dynamics. Experiments are presented for a flat disk and a curved bowl, establishing the optimum height of release, rotation rate and tube orientation. Vibrations were imposed to investigate the changes in the film formation. We discuss the implications of our results in the VFD.

  14. Mechanical Properties of Gels; Stress from Confined Fluids

    SciTech Connect

    George W. Scherer

    2009-12-01

    Abstract for Grant DE-FG02-97ER45642 Period: 1997-2002 Mechanical Properties of Gels 2002-2008 Stress from Confined Fluids Principal investigator: Prof. George W. Scherer Dept. Civil & Env. Eng./PRISM Eng. Quad. E-319 Princeton, NJ 08544 USA Recipient organization: Trustees of Princeton University 4 New South Princeton, NJ 08544 USA Abstract: The initial stage of this project, entitled Mechanical Properties of Gels, was dedicated to characterizing and explaining the properties of inorganic gels. Such materials, made by sol-gel processing, are of interest for fabrication of films, fibers, optical devices, advanced insulation and other uses. However, their poor mechanical properties are an impediment in some applications, so understanding the origin of these properties could lead to enhanced performance. Novel experimental methods were developed and applied to measure the stiffness and permeability of gels and aerogels. Numerical simulations were developed to reproduce the growth process of the gels, resulting in structures whose mechanical properties matched the measurements. The models showed that the gels are formed by the growth of relatively robust clusters of molecules that are joined by tenuous links whose compliance compromises the stiffness of the structure. Therefore, synthetic methods that enhance the links could significantly increase the rigidity of such gels. The next stage of the project focused on Stress from Confined Fluids. The first problem of interest was the enhanced thermal expansion coefficient of water that we measured in the nanometric pores of cement paste. This could have a deleterious effect on the resistance of concrete to rapid heating in fires, because the excessive thermal expansion of water in the pores of the concrete could lead to spalling and collapse. A series of experiments demonstrated that the expansion of water increases as the pore size decreases. To explain this behavior, we undertook a collaboration with Prof. Stephen

  15. Pulsation dampening device for super critical fluid expansion engine, hydraulic engine or pump in cryogenic service

    SciTech Connect

    Ness, L.A.

    1989-11-07

    This patent describes a surge bottle or pressure pulsation dampening device for cryogenic services. It comprises: a liquid sump section, wherein the liquid sump section is comprised of an enclosed area containing a volume of an incompressible fluid; a warm gas volume section, wherein the warm gas volume section is comprised of an enclosed area containing a volume of a compressible warm gas; and a laminar flow section which connects and allows for communication between the liquid sump section and the warm gas volume section. The laminar flow section is comprised of a number of small bore, thin walled tubes which contain the incompressible fluid in the end connected to the liquid sump section and the compressible warm gas in the end connected to the warm gas volume section wherein the bore of the tubes are such that any movement of the either the compressible warm gas or the incompressible fluid would be laminar flow. During operation, the incompressible fluid and the warm compressible gas within the small bore, thin walled tubes move or oscillate a short distance in each of the tubes with minimal intermixing of the incompressible fluid and the warm compressible gas thereby minimizing heat leak from the warm gas volume section to the liquid sump section into the liquid in the sump.

  16. Dynamics of fluid and light intensity in mechanically stirred photobioreactor.

    PubMed

    Zhang, T

    2013-10-10

    Turbulent flows in a single-stage and a two-stage impeller-stirred photobioreactor with a simple geometric configuration were analyzed using computational fluid dynamics. The trajectories of the microorganisms entrained in the flow field were traced by the particle tracking method. By projecting these trajectories onto a radial-axial (r-z) plane with a given azimuth angle, we were able to observe four different dynamics zones: circulation, pure rotation, trap, and slow-motion. Within the pure rotation zone, turbulence can be observed near the edges of the impeller. The light intensity and the light/dark cycles subjected by the microorganisms differ significantly in these zones. These differences can be further changed by providing different incident light illuminations on the reactor surface. The dynamics zones can be altered by modifying the geometric configuration of the reactor and the impeller stirring mechanism. In combination with the utilization of different incident light illuminations, the light intensity dynamics and the light/dark cycles subjected by the microorganisms can be controlled such that an optimal photobioreactor design with a high efficiency of light utilization and a high formation rate of the biochemical products can be realized.

  17. Immunosensor with fluid control mechanism for salivary cortisol analysis.

    PubMed

    Yamaguchi, Masaki; Matsuda, Yohei; Sasaki, Shohei; Sasaki, Makoto; Kadoma, Yoshihiro; Imai, Yoshikatsu; Niwa, Daisuke; Shetty, Vivek

    2013-03-15

    The purpose of this research is to demonstrate a new design for a cortisol immunosensor for the noninvasive and quantitative analysis of salivary cortisol. We propose a cortisol immunosensor with a fluid control mechanism which has both a vertical flow and a lateral flow. The detected current resulting from a competitive reaction between the sample cortisol and a glucose oxidase (GOD)-labeled cortisol conjugate was found to be inversely related to the concentration of cortisol in the sample solution. A calibration curve using the relative detected current showed a R(2)=0.98 and CV=14% for a range of standard cortisol solutions corresponding to the concentrations of native salivary cortisol (0.1-10 ng/ml). The measurement could be accomplished within 35 min and the cortisol immunosensor could be reused. These results show promise for realizing an on-site and easy-to-use biosensor for cortisol. Used for evaluation of human salivary cortisol levels, the cortisol immunosensor measurement corresponded closely with commercially available ELISA method (R(2)=0.92). Our results indicate the promise of the new cortisol immunosensor for noninvasive, point of care measurement of human salivary cortisol levels.

  18. RECENT ADVANCES IN COMPUTATIONAL MECHANICS FOR CIVIL ENGINEERING

    NASA Astrophysics Data System (ADS)

    Applied Mechanics Committee, Computational Mechanics Subcommittee,

    In order to clarify mechanical phenomena in civil engineering, it is necessary to improve computational theory and technique in consideration of the particularity of objects to be analyzed and to update computational mechanics focusing on practical use. In addition to the analysis of infrastructure, for damage prediction of natural disasters such as earthquake, tsunami and flood, since it is essential to reflect broad ranges in space and time inherent to fields of civil engineering as well as material properties, it is important to newly develop computational method in view of the particularity of fields of civil engineering. In this context, research trend of methods of computational mechanics which is noteworthy for resolving the complex mechanics problems in civil engineering is reviewed in this paper.

  19. 20. Photocopy of drawing (1961 mechanical drawing by Kaiser Engineers) ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. Photocopy of drawing (1961 mechanical drawing by Kaiser Engineers) ELECTRICAL LAYOUTS FOR VEHICLE SUPPORT BUILDING, SHEET E-2 - Vandenberg Air Force Base, Space Launch Complex 3, Vehicle Support Building, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  20. Quarterly Bulletin of the Division of Mechanical Engineering and the National Aeronautical Establishment, 1 October to 31 December 1975.

    DTIC Science & Technology

    AERONAUTICS, * MECHANICAL ENGINEERING , SHIPS, CONTROL SYSTEMS, AIRCRAFT, CANADA, HUMAN FACTORS ENGINEERING, GAS DYNAMICS, MECHANICS, FUELS, ENGINES, MARINE ENGINEERING, HYDRODYNAMICS, HARBORS, AERODYNAMICS, FLIGHT RECORDERS.

  1. Controlling health risks from workplace exposure to metalworking fluids in the United Kingdom engineering industry.

    PubMed

    Stear, Martin A

    2003-11-01

    On October 15, 2002, the United Kingdom (UK) Health and Safety Executive (HSE) launched new guidance for the engineering industry, aimed at reducing health risks from metalworking fluids (MWFs). This guidance was the culmination of many years of work on this subject. In the early 1990s, the UK occupational exposure standards (OES) for oil mist were 5 mg/m(-3) 8-hour time-weighted average (TWA), and 10 mg/m(-3) short-term exposure limit (STEL). This was only applicable to highly refined mineral oil mists and there was no exposure limit for water-mix MWFs (emulsions, semi-synthetics, and synthetics). HSE therefore undertook to review the existing exposure limit for neat mineral oil mists (neat oils are fluids that contain highly refined mineral oils and additives, and are used neat without mixing with water) and consider developing one for water-mix MWFs. This led to the development of new air-sampling methods, a comprehensive survey, and the development of new good practice guidance in the place of statutory exposure limits. This new good practice guidance has been endorsed and launched with the help of relevant industry supplier, employer, and employee associations. The guidance builds on the philosophy of tackling health risks as a holistic approach; for example, not just tackling mist control through the use of ventilation, but also fluid selection, fluid delivery, and fluid management (fluid management means to effectively manage all aspects of the fluid, from storage and stock preparation to sump cleaning and fluid disposal, etc.). Tools, such as laminated task sheets, are provided to make it user friendly. It also demonstrates the business benefits from this approach, that managing your MWFs effectively can reduce the incidence of ill health, reduce fluid and disposal costs, increase tool life, and improve machining performance.

  2. Nanoscale engineering materials by supercritical fluid and atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Peng, Qing

    , complex coaxial Al2O3/ZnO/Al2O3 multilayed microtubular structure is fabricated, which provides an unique platform to study the solid state reaction and diffusion process (Kirkendall Effect) between Al2 O3 shells and the confined middle ZnO layers by annealing the samples at 700°C. (6) The extension of ALD-MLD process of polyamides, zinc hybrid, aminosilane self assembly monolayers were studied by various techniques to illustrate the surface reaction mechanism.

  3. Welcoming speech from Dean Faculty of Mechanical Engineering, UMP

    NASA Astrophysics Data System (ADS)

    Taha, Zahari

    2012-09-01

    In the Name of Allah, the Most Beneficent, the Most Merciful. It is with great pleasure that I welcome the participants of the International Conference of Mechanical Engineering Research 2011. The Prophet Muhammad (peace be upon him) said 'Acquire knowledge and impart it to the people.' (Al Tirmidhi). The quest for knowledge has been from the beginning of time but knowledge only becomes valuable when it is disseminated and applied to benefit humankind. It is hoped that ICMER 2011 will be a platform to gather and disseminate the latest knowledge in mechanical engineering. Academicians, Scientist, Researchers and practitioners of mechanical engineering will be able to share and discuss new findings and applications of mechanical engineering. It is envisaged that the intellectual discourse will result in future collaborations between universities, research institutions and industry both locally and internationally. In particular it is expected that focus will be given to issues on environmental and energy sustainability. Researchers in the mechanical engineering faculty at UMP have a keen interest in technology to harness energy from the ocean. Lowering vehicle emissions has been a primary goal of researchers in the mechanical engineering faculty and the automotive engineering centre as well including developing vehicles using alternative fuels such as biodiesel and renewable sources such as solar driven electric vehicles. Finally I would like to congratulate the organizing committee for their tremendous efforts in organizing the conference. As I wrote this in the Holy Land of Makkah, I pray to Allah swt that the conference will be a success. Prof. Dr. Zahari Taha CEng, MIED, FASc Dean, Faculty of Mechanical Engineering Universiti Malaysia Pahang

  4. Mechanical Engineering at KSC: 'How I spend My Hours from 9 to 5 and Draw a Paycheck'

    NASA Technical Reports Server (NTRS)

    Randazzo, John; Steinrock. Todd (Technical Monitor)

    2003-01-01

    This viewgraph presentation provides an overview of a senior mechanical engineer's role in designing and testing sensors to fly aboard the shuttle Discovery during STS-95 and STS-98. Topics covered include: software development tools, computation fluid dynamics, structural analysis, housing design, and systems integration.

  5. Left ventricular muscle and fluid mechanics in acute myocardial infarction.

    PubMed

    Nucifora, Gaetano; Delgado, Victoria; Bertini, Matteo; Marsan, Nina Ajmone; Van de Veire, Nico R; Ng, Arnold C T; Siebelink, Hans-Marc J; Schalij, Martin J; Holman, Eduard R; Sengupta, Partho P; Bax, Jeroen J

    2010-11-15

    Left ventricular (LV) diastolic filling is characterized by the formation of intraventricular rotational bodies of fluid (termed "vortex rings") that optimize the efficiency of LV ejection. The aim of the present study was to evaluate the morphology and dynamics of LV diastolic vortex ring formation early after acute myocardial infarction (AMI), in relation to LV diastolic function and infarct size. A total of 94 patients with a first ST-segment elevation AMI (59 ± 11 years; 78% men) were included. All patients underwent primary percutaneous coronary intervention. After 48 hours, the following examinations were performed: 2-dimensional echocardiography with speckle-tracking analysis to assess the LV systolic and diastolic function, the vortex formation time (VFT, a dimensionless index for characterizing vortex formation), and the LV untwisting rate; contrast echocardiography to assess LV vortex morphology; and myocardial contrast echocardiography to identify the infarct size. Patients with a large infarct size (≥ 3 LV segments) had a significantly lower VFT (p <0.001) and vortex sphericity index (p <0.001). On univariate analysis, several variables were significantly related to the VFT, including anterior AMI, LV end-systolic volume, LV ejection fraction, grade of diastolic dysfunction, LV untwisting rate, and infarct size. On multivariate analysis, the LV untwisting rate (β = -0.43, p <0.001) and infarct size (β = -0.33, p = 0.005) were independently associated with VFT. In conclusion, early in AMI, both the LV infarct size and the mechanical sequence of diastolic restoration play key roles in modulating the morphology and dynamics of early diastolic vortex ring formation.

  6. Mechanics of undulatory swimming in a frictional fluid.

    PubMed

    Ding, Yang; Sharpe, Sarah S; Masse, Andrew; Goldman, Daniel I

    2012-01-01

    The sandfish lizard (Scincus scincus) swims within granular media (sand) using axial body undulations to propel itself without the use of limbs. In previous work we predicted average swimming speed by developing a numerical simulation that incorporated experimentally measured biological kinematics into a multibody sandfish model. The model was coupled to an experimentally validated soft sphere discrete element method simulation of the granular medium. In this paper, we use the simulation to study the detailed mechanics of undulatory swimming in a "granular frictional fluid" and compare the predictions to our previously developed resistive force theory (RFT) which models sand-swimming using empirically determined granular drag laws. The simulation reveals that the forward speed of the center of mass (CoM) oscillates about its average speed in antiphase with head drag. The coupling between overall body motion and body deformation results in a non-trivial pattern in the magnitude of lateral displacement of the segments along the body. The actuator torque and segment power are maximal near the center of the body and decrease to zero toward the head and the tail. Approximately 30% of the net swimming power is dissipated in head drag. The power consumption is proportional to the frequency in the biologically relevant range, which confirms that frictional forces dominate during sand-swimming by the sandfish. Comparison of the segmental forces measured in simulation with the force on a laterally oscillating rod reveals that a granular hysteresis effect causes the overestimation of the body thrust forces in the RFT. Our models provide detailed testable predictions for biological locomotion in a granular environment.

  7. Analysis of sponge zones for computational fluid mechanics

    SciTech Connect

    Bodony, Daniel J. . E-mail: bodony@stanford.edu

    2006-03-01

    The use of sponge regions, or sponge zones, which add the forcing term -{sigma}(q - q {sub ref}) to the right-hand-side of the governing equations in computational fluid mechanics as an ad hoc boundary treatment is widespread. They are used to absorb and minimize reflections from computational boundaries and as forcing sponges to introduce prescribed disturbances into a calculation. A less common usage is as a means of extending a calculation from a smaller domain into a larger one, such as in computing the far-field sound generated in a localized region. By analogy to the penalty method of finite elements, the method is placed on a solid foundation, complete with estimates of convergence. The analysis generalizes the work of Israeli and Orszag [M. Israeli, S.A. Orszag, Approximation of radiation boundary conditions, J. Comp. Phys. 41 (1981) 115-135] and confirms their findings when applied as a special case to one-dimensional wave propagation in an absorbing sponge. It is found that the rate of convergence of the actual solution to the target solution, with an appropriate norm, is inversely proportional to the sponge strength. A detailed analysis for acoustic wave propagation in one-dimension verifies the convergence rate given by the general theory. The exponential point-wise convergence derived by Israeli and Orszag in the high-frequency limit is recovered and found to hold over all frequencies. A weakly nonlinear analysis of the method when applied to Burgers' equation shows similar convergence properties. Three numerical examples are given to confirm the analysis: the acoustic extension of a two-dimensional time-harmonic point source, the acoustic extension of a three-dimensional initial-value problem of a sound pulse, and the introduction of unstable eigenmodes from linear stability theory into a two-dimensional shear layer.

  8. Teaching Fluid Mechanics to the Beginning Graduate Student--An Objective-Oriented Approach.

    ERIC Educational Resources Information Center

    Liu, Henry

    A premature embarkation in specialized areas of fluid mechanics by the beginning graduate student, without having first thoroughly learned the basics, leads to learning difficulties and destroys zeal for learning. To avoid these problems, many schools in the U.S. offer beginning graduate courses in fluid mechanics (BGCFM). Because the success or…

  9. Optimization of new magnetorheological fluid mount for vibration control of start/stop engine mode

    NASA Astrophysics Data System (ADS)

    Chung, Jye Ung; Phu, Do Xuan; Choi, Seung-Bok

    2015-04-01

    The technologies related to saving energy/or green vehicles are actively researched. In this tendency, the problem for reducing exhausted gas is in development with various ways. Those efforts are directly related to the operation of engine which emits exhausted gas. The auto start/stop of vehicle engine when a vehicle stop at road is currently as a main stream of vehicle industry resulting in reducing exhausted gas. However, this technology automatically turns on and off engine frequently. This motion induces vehicle engine to transmit vibration of engine which has large displacement, and torsional impact to chassis. These vibrations causing uncomfortable feeling to passengers are transmitted through the steering wheel and the gear knob. In this work, in order to resolve this vibration issue, a new proposed magnetorheological (MR) fluid based engine mount (MR mount in short) is presented. The proposed MR mount is designed to satisfy large damping force in various frequency ranges. It is shown that the proposed mount can have large damping force and large force ratio which is enough to control unwanted vibrations of engine start/stop mode.

  10. Engineering a General Education Program: Designing Mechanical Engineering General Education Courses

    ERIC Educational Resources Information Center

    Fagette, Paul; Chen, Shih-Jiun; Baran, George R.; Samuel, Solomon P.; Kiani, Mohammad F.

    2013-01-01

    The Department of Mechanical Engineering at our institution created two engineering courses for the General Education Program that count towards second level general science credit (traditional science courses are first level). The courses were designed for the general student population based upon the requirements of our General Education Program…

  11. Control Engineering as a Part of Undergraduate Curriculum for Mechanical Engineering in India

    ERIC Educational Resources Information Center

    Akhtar, Shagil; Iqbal, Syed Muneeb; Bajpai, Shrish

    2016-01-01

    In this present study we have traced the genesis of control engineering in the scope of mechanical engineering and then some analysis on its recent developments, their increasing need and how this particular subject has evolved machines functioning nowadays specifically its standard of education in India. We have probed this field right from its…

  12. Deconstructing Engineering Education Programmes: The DEEP Project to Reform the Mechanical Engineering Curriculum

    ERIC Educational Resources Information Center

    Busch-Vishniac, Ilene; Kibler, Tom; Campbell, Patricia B.; Patterson, Eann; Guillaume, Darrell; Jarosz, Jeffrey; Chassapis, Constantin; Emery, Ashley; Ellis, Glenn; Whitworth, Horace; Metz, Susan; Brainard, Suzanne; Ray, Pradosh

    2011-01-01

    The goal of the Deconstructing Engineering Education Programmes project is to revise the mechanical engineering undergraduate curriculum to make the discipline more able to attract and retain a diverse community of students. The project seeks to reduce and reorder the prerequisite structure linking courses to offer greater flexibility for…

  13. Valve actuating mechanism for internal combustion engine

    SciTech Connect

    Kuroda, Y.

    1987-01-20

    This patent describes an internal combustion engine comprising a cylinder having a bore, a cylinder head fixed relative to the cylinder, and three poppet type valves supported by the cylinder head for reciprocation about respective axes all positioned on the same side of a plane containing the axis of the cylinder bore. It also comprises a single camshaft having three respective cam lobes each associated with a respective of the valves, the camshaft being rotatable about an axis extending parallel to the plane and lying on the same side thereof as the valve axes. A rocker arms means is associated with one of the cam lobes for operating its associated valve, and means is included for directly operating the remainder of the valves from the remaining cam lobes.

  14. Control Engineering Analysis of Mechanical Pitch Systems

    NASA Astrophysics Data System (ADS)

    Bernicke, Olaf; Gauterin, Eckhard; Schulte, Horst; Zajac, Michal

    2014-12-01

    With the help of a local stability analysis the coefficient range of a discrete damper, used for centrifugal forced, mechanical pitch system of small wind turbines (SWT), is gained for equilibrium points. - By a global stability analysis the gained coefficient range can be validated. An appropriate approach by Takagi-Sugeno is presented in the paper.

  15. Influence of Reduced Mass Flow Rate and Chamber Backpressure on Swirl Injector Fluid Mechanics

    NASA Technical Reports Server (NTRS)

    Kenny, R Jeremy; Hulka, James R.

    2008-01-01

    Industry interest in variable-thrust liquid rocket engines places a demand on engine injector technology to operate over a wide range of liquid mass flow rates and chamber backpressures. One injection technology of current interest for variable thrust applications is an injector design with swirled fluids. Current swirl injector design methodologies do not take into account how swirl injector design parameters respond to elevated chamber backpressures at less than design mass flow rates. The current work was created to improve state-of-the-art swirl injector design methods in this area. The specific objective was to study the effects of elevated chamber backpressure and off-design mass flow rates on swirl injector fluid mechanics. Using a backpressure chamber with optical access, water was flowed through a swirl injector at various combinations of chamber backpressure and mass flow rates. The film thickness profile down the swirl injector nozzle section was measured through a transparent nozzle section of the injector. High speed video showed measurable increases in the film thickness profile with application of chamber backpressure and mass flow rates less than design. At prescribed combinations of chamber backpressure and injected mass flow rate, a discrete change in the film thickness profile was observed. Measured injector discharge coefficient values showed different trends with increasing chamber backpressure at low mass flow rates as opposed to near-design mass flow rates. Downstream spray angles showed classic changes in morphology as the mass flow rate was decreased below the design value. Increasing chamber backpressure decreased the spray angle at any injection mass flow rate. Experimental measurements and discussion of these results are reported in this paper.

  16. Modelling of a hydraulic engine mount with fluid-structure interaction finite element analysis

    NASA Astrophysics Data System (ADS)

    Shangguan, Wen-Bin; Lu, Zhen-Hua

    2004-08-01

    Hydraulic engine mount (HEM) is now widely used as a highly effective vibration isolator in automotive powertrain. A lumped parameter (LP) model is a traditional model for modelling the dynamic characteristics of HEM, in which the system parameters are usually obtained by experiments. In this paper, a fluid-structure interaction (FSI) finite element analysis (FEA) method and a non-linear FEA technology are used to determine the system parameters, and a fully coupled FSI model is developed for modelling the static and lower-frequency performance of an HEM. A FSI FEA technique is used to estimate the parameters of volumetric compliances, equivalent piston area, inertia and resistance of the fluid in the inertia track and the decoupler of an HEM. A non-linear FEA method is applied to determine the dynamic stiffness of rubber spring of the HEM. The system parameters predicated by FEA are compared favorably with experimental data and/or analytical solutions. A numerical simulation for an HEM with an inertia track and a free decoupler is performed based on the FSI model and the LP model along with the estimated system parameters, and again the simulation results are compared with experimental data. The calculated time histories of some variables in the model, such as the pressure in the upper chamber, the displacement of the free decoupler and the volume flow through the inertia track and the decoupler, under different excitations, elucidate the working mechanism of the HEM. The pressure distribution calculated with the FSI model in the chambers of the HEM validates the assumption that the pressure distribution in the upper and lower chamber is uniform in the LP model. The work conducted in the paper demonstrates that the methods for estimating the system parameters in the LP model and the FSI model for modelling HEM are effective, with which the dynamic characteristic analysis and design optimization of an HEM can be performed before its prototype development, and this

  17. Valve actuating mechanism for internal combustion engine

    SciTech Connect

    Tsuchida, N.

    1986-06-03

    A valve train for an internal combustion engine is described having a cylinder head assembly, a first poppet valve supported by the cylinder head assembly for reciprocation along an axis defined by its stem, a second poppet valve supported by the cylinder head assembly for reciprocation along an axis defined by its stem, a camshaft supported by the cylinder head assembly for rotation about a rotational axis intersected by the first poppet valve stem axis, cam means on the camshaft, a tappet slidably supported by the cylinder head assembly and associated with the cam means and the first valve for opening directly the first valve, a rocker arm supported for pivotal movement and associated with the cam means for pivoting the rocker arm, and means on the rocker arm operative to actuate the second valve upon pivotal movement of the rocker arm. The improvement described here consists of the rocker arm being pivotally supported by a rocker arm shaft carried by the cylinder head assembly and lubricant passage means extending through the cylinder head assembly and through the rocker arm shaft for lubricating the pivotal support for the rocker arm and the sliding support for the tappet.

  18. Investigation of the in vitro culture process for skeletal-tissue-engineered constructs using computational fluid dynamics and experimental methods.

    PubMed

    Hossain, Md Shakhawath; Chen, X B; Bergstrom, D J

    2012-12-01

    The in vitro culture process via bioreactors is critical to create tissue-engineered constructs (TECs) to repair or replace the damaged tissues/organs in various engineered applications. In the past, the TEC culture process was typically treated as a black box and performed on the basis of trial and error. Recently, computational fluid dynamics (CFD) has demonstrated its potential to analyze the fluid flow inside and around the TECs, therefore, being able to provide insight into the culture process, such as information on the velocity field and shear stress distribution that can significantly affect such cellular activities as cell viability and proliferation during the culture process. This paper briefly reviews the CFD and experimental methods used to investigate the in vitro culture process of skeletal-type TECs in bioreactors, where mechanical deformation of the TEC can be ignored. Specifically, this paper presents CFD modeling approaches for the analysis of the velocity and shear stress fields, mass transfer, and cell growth during the culture process and also describes various particle image velocimetry (PIV) based experimental methods to measure the velocity and shear stress in the in vitro culture process. Some key issues and challenges are also identified and discussed along with recommendations for future research.

  19. Hydro-mechanical overhead for internal combustion engine

    SciTech Connect

    Meistrick, Z.S.; Price, R.B.

    1987-05-12

    This patent describes a hydro-mechanical overhead for a multi-cylinder four-cycle internal combustion engine having a camshaft, intake valve pushtube means driven by the camshaft, exhaust valve pushtube means driven by the camshaft, at least one intake and exhaust valve for each cylinder of the multi-cylinder internal combustion engines and a piston for each cylinder of the engine. The process comprises an intake valve master piston means for each engine cylinder. Each intake valve master piston means is driven by one of the intake valve pushtube means. There is an exhaust valve master piston means for each engine cylinder, and each exhaust valve master piston means is driven by one of the exhaust valve pushtube means.

  20. Cell patterning for liver tissue engineering via dielectrophoretic mechanisms.

    PubMed

    Yahya, Wan Nurlina Wan; Kadri, Nahrizul Adib; Ibrahim, Fatimah

    2014-07-02

    Liver transplantation is the most common treatment for patients with end-stage liver failure. However, liver transplantation is greatly limited by a shortage of donors. Liver tissue engineering may offer an alternative by providing an implantable engineered liver. Currently, diverse types of engineering approaches for in vitro liver cell culture are available, including scaffold-based methods, microfluidic platforms, and micropatterning techniques. Active cell patterning via dielectrophoretic (DEP) force showed some advantages over other methods, including high speed, ease of handling, high precision and being label-free. This article summarizes liver function and regenerative mechanisms for better understanding in developing engineered liver. We then review recent advances in liver tissue engineering techniques and focus on DEP-based cell patterning, including microelectrode design and patterning configuration.

  1. Cell Patterning for Liver Tissue Engineering via Dielectrophoretic Mechanisms

    PubMed Central

    Yahya, Wan Nurlina Wan; Kadri, Nahrizul Adib; Ibrahim, Fatimah

    2014-01-01

    Liver transplantation is the most common treatment for patients with end-stage liver failure. However, liver transplantation is greatly limited by a shortage of donors. Liver tissue engineering may offer an alternative by providing an implantable engineered liver. Currently, diverse types of engineering approaches for in vitro liver cell culture are available, including scaffold-based methods, microfluidic platforms, and micropatterning techniques. Active cell patterning via dielectrophoretic (DEP) force showed some advantages over other methods, including high speed, ease of handling, high precision and being label-free. This article summarizes liver function and regenerative mechanisms for better understanding in developing engineered liver. We then review recent advances in liver tissue engineering techniques and focus on DEP-based cell patterning, including microelectrode design and patterning configuration. PMID:24991941

  2. Sensing fluid viscosity and density through mechanical impedance measurement using a whisker transducer

    NASA Astrophysics Data System (ADS)

    Ju, Feng; Ling, Shih-Fu

    2013-05-01

    This paper presents a new technique for fluid viscosity and density sensing through measuring the mechanical impedance of the fluid load applied on a sphere. A piezoelectric whisker transducer (WT) is proposed which acts simultaneously as both the actuator to excite the sphere tip to oscillate in the fluid and the sensor to measure the force, velocity and mechanical impedance. The relationship between mechanical impedance of the fluid load and electrical impedance of the WT is derived based on a transduction matrix model which characterizes the electro-mechanical transduction process of the WT in both directions. The mechanical impedance is further related to the fluid viscosity and density using a theoretical model. The establishment of this fluid-mechanical-electrical relationship allows the WT to extract the fluid viscosity and density conveniently and accurately just from its electrical impedance. Experimental studies are carried out to calibrate the WT and test its performance using glycerol-water mixtures. It is concluded that the WT is capable of providing results comparable to those of standard viscometers within a wide measurement range due to its low working frequency and large vibration amplitude. Its unique self-actuation-and-sensing feature makes it a suitable solution for online fluid sensing.

  3. Interactive Approach on Experiments in Mechanical Engineering : Vibration

    NASA Astrophysics Data System (ADS)

    Kumon, Makoto; Torigoe, Ippei; Mizumoto, Ikuro; Yamaguchi, Teruo; Kohzawa, Ryuichi; Ohshima, Yasutaka

    Experiments in the engineering education play important roles in motivating students to study voluntarily. A trial aiming to enhance this effect in the experiment of vibration at Mechanical System Engineering, Kumamoto University is introduced. The trial consists of 1) oral presentation by students, 2) web-based learning system and 3) feedback through reports. An evaluation by questionnaire was conducted to show the validity of this trial. This result revealed that the trial succeeded to encourage students.

  4. MECHANICAL DESIGN CRITERIA FOR INTERVERTEBRAL DISC TISSUE ENGINEERING

    PubMed Central

    Nerurkar, Nandan L.; Elliott, Dawn M.; Mauck, Robert L.

    2009-01-01

    Due to the inability of current clinical practices to restore function to degenerated intervertebral discs, the arena of disc tissue engineering has received substantial attention in recent years. Despite tremendous growth and progress in this field, translation to clinical implementation has been hindered by a lack of well-defined functional benchmarks. Because successful replacement of the disc is contingent upon replication of some or all of its complex mechanical behaviour, it is critically important that disc mechanics be well characterized in order to establish discrete functional goals for tissue engineering. In this review, the key functional signatures of the intervertebral disc are discussed and used to propose a series of native tissue benchmarks to guide the development of engineered replacement tissues. These benchmarks include measures of mechanical function under tensile, compressive and shear deformations for the disc and its substructures. In some cases, important functional measures are identified that have yet to be measured in the native tissue. Ultimately, native tissue benchmark values are compared to measurements that have been made on engineered disc tissues, identifying measures where functional equivalence was achieved, and others where there remain opportunities for advancement. Several excellent reviews exist regarding disc composition and structure, as well as recent tissue engineering strategies; therefore this review will remain focused on the functional aspects of disc tissue engineering. PMID:20080239

  5. 46 CFR 113.35-15 - Mechanical engine order telegraph systems; application.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Mechanical engine order telegraph systems; application...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-15 Mechanical engine order telegraph systems; application. If a mechanical engine order...

  6. 46 CFR 113.35-15 - Mechanical engine order telegraph systems; application.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Mechanical engine order telegraph systems; application...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-15 Mechanical engine order telegraph systems; application. If a mechanical engine order...

  7. 46 CFR 113.35-15 - Mechanical engine order telegraph systems; application.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Mechanical engine order telegraph systems; application...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-15 Mechanical engine order telegraph systems; application. If a mechanical engine order...

  8. 46 CFR 113.35-15 - Mechanical engine order telegraph systems; application.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Mechanical engine order telegraph systems; application...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-15 Mechanical engine order telegraph systems; application. If a mechanical engine order...

  9. 46 CFR 113.35-15 - Mechanical engine order telegraph systems; application.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Mechanical engine order telegraph systems; application...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-15 Mechanical engine order telegraph systems; application. If a mechanical engine order...

  10. Teaching Computer-Aided Design of Fluid Flow and Heat Transfer Engineering Equipment.

    ERIC Educational Resources Information Center

    Gosman, A. D.; And Others

    1979-01-01

    Describes a teaching program for fluid mechanics and heat transfer which contains both computer aided learning (CAL) and computer aided design (CAD) components and argues that the understanding of the physical and numerical modeling taught in the CAL course is essential to the proper implementation of CAD. (Author/CMV)

  11. Mechanisms of protein evolution and their application to protein engineering.

    PubMed

    Glasner, Margaret E; Gerlt, John A; Babbitt, Patricia C

    2007-01-01

    Protein engineering holds great promise for the development of new biosensors, diagnostics, therapeutics, and agents for bioremediation. Despite some remarkable successes in experimental and computational protein design, engineered proteins rarely achieve the efficiency or specificity of natural enzymes. Current protein design methods utilize evolutionary concepts, including mutation, recombination, and selection, but the inability to fully recapitulate the success of natural evolution suggests that some evolutionary principles have not been fully exploited. One aspect of protein engineering that has received little attention is how to select the most promising proteins to serve as templates, or scaffolds, for engineering. Two evolutionary concepts that could provide a rational basis for template selection are the conservation of catalytic mechanisms and functional promiscuity. Knowledge of the catalytic motifs responsible for conserved aspects of catalysis in mechanistically diverse superfamilies could be used to identify promising templates for protein engineering. Second, protein evolution often proceeds through promiscuous intermediates, suggesting that templates which are naturally promiscuous for a target reaction could enhance protein engineering strategies. This review explores these ideas and alternative hypotheses concerning protein evolution and engineering. Future research will determine if application of these principles will lead to a protein engineering methodology governed by predictable rules for designing efficient, novel catalysts.

  12. Computational Fluid Dynamics Analysis Method Developed for Rocket-Based Combined Cycle Engine Inlet

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Renewed interest in hypersonic propulsion systems has led to research programs investigating combined cycle engines that are designed to operate efficiently across the flight regime. The Rocket-Based Combined Cycle Engine is a propulsion system under development at the NASA Lewis Research Center. This engine integrates a high specific impulse, low thrust-to-weight, airbreathing engine with a low-impulse, high thrust-to-weight rocket. From takeoff to Mach 2.5, the engine operates as an air-augmented rocket. At Mach 2.5, the engine becomes a dual-mode ramjet; and beyond Mach 8, the rocket is turned back on. One Rocket-Based Combined Cycle Engine variation known as the "Strut-Jet" concept is being investigated jointly by NASA Lewis, the U.S. Air Force, Gencorp Aerojet, General Applied Science Labs (GASL), and Lockheed Martin Corporation. Work thus far has included wind tunnel experiments and computational fluid dynamics (CFD) investigations with the NPARC code. The CFD method was initiated by modeling the geometry of the Strut-Jet with the GRIDGEN structured grid generator. Grids representing a subscale inlet model and the full-scale demonstrator geometry were constructed. These grids modeled one-half of the symmetric inlet flow path, including the precompression plate, diverter, center duct, side duct, and combustor. After the grid generation, full Navier-Stokes flow simulations were conducted with the NPARC Navier-Stokes code. The Chien low-Reynolds-number k-e turbulence model was employed to simulate the high-speed turbulent flow. Finally, the CFD solutions were postprocessed with a Fortran code. This code provided wall static pressure distributions, pitot pressure distributions, mass flow rates, and internal drag. These results were compared with experimental data from a subscale inlet test for code validation; then they were used to help evaluate the demonstrator engine net thrust.

  13. Sputtering. [as deposition technique in mechanical engineering

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1976-01-01

    This paper primarily reviews the potential of using the sputtering process as a deposition technique; however, the manufacturing and sputter etching aspects are also discussed. Since sputtering is not regulated by classical thermodynamics, new multicomponent materials can be developed in any possible chemical composition. The basic mechanism for dc and rf sputtering is described. Sputter-deposition is described in terms of the unique advantageous features it offers such as versatility, momentum transfer, stoichiometry, sputter-etching, target geometry (coating complex surfaces), precise controls, flexibility, ecology, and sputtering rates. Sputtered film characteristics, such as strong adherence and coherence and film morphology, are briefly evaluated in terms of varying the sputtering parameters. Also described are some of the specific industrial areas which are turning to sputter-deposition techniques.

  14. A biocompatible tissue scaffold produced by supercritical fluid processing for cartilage tissue engineering.

    PubMed

    Kim, Su Hee; Jung, Youngmee; Kim, Soo Hyun

    2013-03-01

    Supercritical fluids are used in various industrial fields, such as the food and medical industries, because they have beneficial physical and chemical properties and are also nonflammable and inexpensive. In particular, supercritical carbon dioxide (ScCO(2)) is attractive due to its mild critical temperature, pressure values, and nontoxicity. Poly(L-lactide-co-ɛ-caprolactone) (PLCL), which is a biocompatible, biodegradable, and very elastic polymer, has been used in cartilage tissue engineering. However, organic solvents, such as chloroform or dichloromethane, are usually used for the fabrication of a PLCL scaffold through conventional methods. This leads to a cytotoxic effect and long processing time for removing solvents. To alleviate these problems, supercritical fluid processing is introduced here. In this study, we fabricated a mechano-active PLCL scaffold by supercritical fluid processing for cartilage tissue engineering, and we compared it with a scaffold made by a conventional solvent-casting method in terms of physical and biological performance. Also, to examine the optimum condition for preparing scaffolds with ScCO(2), we investigated the effects of pressure, temperature, and the depressurization rate on PLCL foaming. The PLCL scaffolds produced by supercritical fluid processing had a homogeneously interconnected porous structure, and they exhibited a narrow pore size distribution. Also, there was no cytotoxicity of the scaffolds made with ScCO(2) compared to the scaffolds made by the solvent-pressing method. The scaffolds were seeded with chondrocytes, and they were subcutaneously implanted into nude mice for up to 4 weeks. In vivo accumulation of extracellular matrix of cell-scaffold constructs demonstrated that the PLCL scaffold made with ScCO(2) formed a mature and well-developed cartilaginous tissue compared to the PLCL scaffold formed by solvent pressing. Consequently, these results indicated that the PLCL scaffolds made by supercritical fluid

  15. Engineering three-dimensional cell mechanical microenvironment with hydrogels.

    PubMed

    Huang, Guoyou; Wang, Lin; Wang, Shuqi; Han, Yulong; Wu, Jinhui; Zhang, Qiancheng; Xu, Feng; Lu, Tian Jian

    2012-12-01

    Cell mechanical microenvironment (CMM) significantly affects cell behaviors such as spreading, migration, proliferation and differentiation. However, most studies on cell response to mechanical stimulation are based on two-dimensional (2D) planar substrates, which cannot mimic native three-dimensional (3D) CMM. Accumulating evidence has shown that there is a significant difference in cell behavior in 2D and 3D microenvironments. Among the materials used for engineering 3D CMM, hydrogels have gained increasing attention due to their tunable properties (e.g. chemical and mechanical properties). In this paper, we provide an overview of recent advances in engineering hydrogel-based 3D CMM. Effects of mechanical cues (e.g. hydrogel stiffness and externally induced stress/strain in hydrogels) on cell behaviors are described. A variety of approaches to load mechanical stimuli in 3D hydrogel-based constructs are also discussed.

  16. Neutron imaging of hydrogen-rich fluids in geomaterials and engineered porous media: A review

    NASA Astrophysics Data System (ADS)

    Perfect, E.; Cheng, C.-L.; Kang, M.; Bilheux, H. Z.; Lamanna, J. M.; Gragg, M. J.; Wright, D. M.

    2014-02-01

    Recent advances in visualization technologies are providing new discoveries as well as answering old questions with respect to the phase structure and flow of hydrogen-rich fluids, such as water and oil, within porous media. Magnetic resonance and x-ray imaging are sometimes employed in this context, but are subject to significant limitations. In contrast, neutrons are ideally suited for imaging hydrogen-rich fluids in abiotic non-hydrogenous porous media because they are strongly attenuated by hydrogen and can "see" through the solid matrix in a non-destructive fashion. This review paper provides an overview of the general principles behind the use of neutrons to image hydrogen-rich fluids in both 2-dimensions (radiography) and 3-dimensions (tomography). Engineering standards for the neutron imaging method are examined. The main body of the paper consists of a comprehensive review of the diverse scientific literature on neutron imaging of static and dynamic experiments involving variably-saturated geomaterials (rocks and soils) and engineered porous media (bricks and ceramics, concrete, fuel cells, heat pipes, and porous glass). Finally some emerging areas that offer promising opportunities for future research are discussed.

  17. Development of a peristaltic crawling robot using magnetic fluid on the basis of the locomotion mechanism of the earthworm

    NASA Astrophysics Data System (ADS)

    Saga, Norihiko; Nakamura, Taro

    2004-06-01

    In the field of bio-engineering the aim of developing new machines which utilize the motion and control of organisms as a model is attracting attention. This technology is pursued by paying attention to various shapes and movements of organisms and autonomous system of organisms that act in response to the environment surrounding them, and by mechanically elucidating the locomotion mechanism, propulsive mechanism, nerve system and sensation system for these organisms. On the other hand, in the field of hydrodynamics, magnetic fluid that changes its apparent viscosity depending on the magnetic field has been developed, and its utilization is under trial in various fields. Attention has been paid to the peristaltic crawling of the earthworm as a transport function in place of wheels or ambulation, and based on these observations a micro-robot running inside a tube using magnetic fluid has been developed. In this micro-robot, individual cells corresponding to the earthworm's segment are composed of a natural rubber tube sealed with water-based magnetic fluid, and several cells are connected with elastic rods made of natural rubber. The feature of this micro-robot is that its structure is simply composed, and it can be controlled with external wireless force, by providing it with moving magnetism from the outside. This paper presents the analytical result on the peristaltic crawling of an actual earthworm and the evaluation result for the transport mechanism of a prototype micro-robot moved by an external magnetic field.

  18. Mechanical Architecture and Engineering of PAZ Instrument

    NASA Astrophysics Data System (ADS)

    Bautista Juzgado, Victor

    2012-07-01

    PAZ is a highly flexible X-Band Synthetic Aperture Radar satellite devoted to global Earth Observation. It fulfills the strategic needs of the Spanish Government within the National Earth Observation Program. This satellite will be capable of providing high quality SAR images up to very high resolution (e.g. meter and sub- meter). Its flexibility lies on the various instrument modes (Stripmap, ScanSAR, Sporlight...) with a wide number of configurations, both in left and right-looking scanning. The S/C will cover the Earth with a mean revisit time of 1 day taking around 200000 images per day over an area above 300000km2. In the frame of this program, EADS CASA Espacio (ECE) stands as satellite prime contractor as well as responsible for the design and development of the SAR instrument, also called Front End. This paper describes the mechanical architecture, driving requirements, analyses, tests and main challenges found during the Front End development at ECE from the structural point of view.

  19. Semi-active engine mount design using auxiliary magneto-rheological fluid compliance chamber

    NASA Astrophysics Data System (ADS)

    Mansour, H.; Arzanpour, S.; Golnaraghi, M. F.; Parameswaran, A. M.

    2011-03-01

    Engine mounts are used in the automotive industry to isolate engine and chassis by reducing the noise and vibration imposed from one to the other. This paper describes modelling, simulation and design of a semi-active engine mount that is designed specifically to address the complicated vibration pattern of variable displacement engines (VDE). The ideal isolation for VDE requires the stiffness to be switchable upon cylinder activation/deactivation operating modes. In order to have a modular design, the same hydraulic engine mount components are maintained and a novel auxiliary magneto-rheological (MR) fluid chamber is developed and retrofitted inside the pumping chamber. The new compliance chamber is a controllable pressure regulator, which can effectively alter the dynamic performance of the mount. Switching between different modes happens by turning the electrical current to the MR chamber magnetic coil on and off. A model has been developed for the passive hydraulic mount and then it is extended to include the MR auxiliary chamber as well. A proof-of-concept prototype of the design has been fabricated which validates the mathematical model. The results demonstrate unique capability of the developed semi-active mount to be used for VDE application.

  20. A high throughput mechanical screening device for cartilage tissue engineering.

    PubMed

    Mohanraj, Bhavana; Hou, Chieh; Meloni, Gregory R; Cosgrove, Brian D; Dodge, George R; Mauck, Robert L

    2014-06-27

    Articular cartilage enables efficient and near-frictionless load transmission, but suffers from poor inherent healing capacity. As such, cartilage tissue engineering strategies have focused on mimicking both compositional and mechanical properties of native tissue in order to provide effective repair materials for the treatment of damaged or degenerated joint surfaces. However, given the large number design parameters available (e.g. cell sources, scaffold designs, and growth factors), it is difficult to conduct combinatorial experiments of engineered cartilage. This is particularly exacerbated when mechanical properties are a primary outcome, given the long time required for testing of individual samples. High throughput screening is utilized widely in the pharmaceutical industry to rapidly and cost-effectively assess the effects of thousands of compounds for therapeutic discovery. Here we adapted this approach to develop a high throughput mechanical screening (HTMS) system capable of measuring the mechanical properties of up to 48 materials simultaneously. The HTMS device was validated by testing various biomaterials and engineered cartilage constructs and by comparing the HTMS results to those derived from conventional single sample compression tests. Further evaluation showed that the HTMS system was capable of distinguishing and identifying 'hits', or factors that influence the degree of tissue maturation. Future iterations of this device will focus on reducing data variability, increasing force sensitivity and range, as well as scaling-up to even larger (96-well) formats. This HTMS device provides a novel tool for cartilage tissue engineering, freeing experimental design from the limitations of mechanical testing throughput.

  1. A High Throughput Mechanical Screening Device for Cartilage Tissue Engineering

    PubMed Central

    Mohanraj, Bhavana; Hou, Chieh; Meloni, Greg R.; Cosgrove, Brian D.; Dodge, George R.; Mauck, Robert L.

    2014-01-01

    Articular cartilage enables efficient and near-frictionless load transmission, but suffers from poor inherent healing capacity. As such, cartilage tissue engineering strategies have focused on mimicking both compositional and mechanical properties of native tissue in order to provide effective repair materials for the treatment of damaged or degenerated joint surfaces. However, given the large number design parameters available (e.g. cell sources, scaffold designs, and growth factors), it is difficult to conduct combinatorial experiments of engineered cartilage. This is particularly exacerbated when mechanical properties are a primary outcome given the long time required for testing of individual samples. High throughput screening is utilized widely in the pharmaceutical industry to rapidly and cost-effectively assess the effects of thousands of compounds for therapeutic discovery. Here we adapted this approach to develop a high throughput mechanical screening (HTMS) system capable of measuring the mechanical properties of up to 48 materials simultaneously. The HTMS device was validated by testing various biomaterials and engineered cartilage constructs and by comparing the HTMS results to those derived from conventional single sample compression tests. Further evaluation showed that the HTMS system was capable of distinguishing and identifying ‘hits’, or factors that influence the degree of tissue maturation. Future iterations of this device will focus on reducing data variability, increasing force sensitivity and range, as well as scaling-up to even larger (96-well) formats. This HTMS device provides a novel tool for cartilage tissue engineering, freeing experimental design from the limitations of mechanical testing throughput. PMID:24275442

  2. Automatic compression adjusting mechanism for internal combustion engines

    NASA Technical Reports Server (NTRS)

    Akkerman, J. W. (Inventor)

    1983-01-01

    Means for controlling the compression pressure in an internal combustion engine having one or more cylinders and subject to widely varying power output requirements are provided. Received between each crank pin and connecting rod is an eccentric sleeve selectively capable of rotation about the crank pin and/or inside the rod and for latching with the rod to vary the effective length of the connecting rod and thereby the clearance volume of the engine. The eccentric normally rotates inside the connecting rod during the exhaust and intake strokes but a latching pawl carried by the eccentric is movable radially outwardly to latch the rod and eccentric together during the compression and power strokes. A control valve responds to intake manifold pressure to time the supply of hydraulic fluid to move the latch-pawl outwardly, varying the effective rod length to maintain a substantially optimum firing chamber pressure at all intake manifold pressures.

  3. Revisiting Newtonian and Non-Newtonian Fluid Mechanics Using Computer Algebra

    ERIC Educational Resources Information Center

    Knight, D. G.

    2006-01-01

    This article illustrates how a computer algebra system, such as Maple[R], can assist in the study of theoretical fluid mechanics, for both Newtonian and non-Newtonian fluids. The continuity equation, the stress equations of motion, the Navier-Stokes equations, and various constitutive equations are treated, using a full, but straightforward,…

  4. Fluid mechanics phenomena in microgravity; ASME Winter Annual Meeting, Anaheim, CA, Nov. 8-13, 1992

    NASA Technical Reports Server (NTRS)

    Siginer, Dennis A. (Editor); Weislogel, Mark M. (Editor)

    1992-01-01

    This paper is the first in a series of symposia presenting research activity in microgravity fluid mechanics. General topics addressed include two-phase flow and transport phenomena, thermo-capillary flow, and interfacial stability. Papers present mathmatical models of fluid dynamics in the microgravity environment. Applications suggested include space manufacturing and storage of liquids in low gravity.

  5. Cerebrospinal Fluid Mechanics and Its Coupling to Cerebrovascular Dynamics

    NASA Astrophysics Data System (ADS)

    Linninger, Andreas A.; Tangen, Kevin; Hsu, Chih-Yang; Frim, David

    2016-01-01

    Cerebrospinal fluid (CSF) is not stagnant but displays fascinating oscillatory flow patterns inside the ventricular system and reversing fluid exchange between the cranial vault and spinal compartment. This review provides an overview of the current knowledge of pulsatile CSF motion. Observations contradicting classical views about its bulk production and clearance are highlighted. A clinical account of diseases of abnormal CSF flow dynamics, including hydrocephalus, syringomyelia, Chiari malformation type 1, and pseudotumor cerebri, is also given. We survey medical imaging modalities used to observe intracranial dynamics in vivo. Additionally, we assess the state of the art in predictive models of CSF dynamics. The discussion addresses open questions regarding CSF dynamics as they relate to the understanding and management of diseases.

  6. A mathematical model of post-instability in fluid mechanics

    NASA Technical Reports Server (NTRS)

    Zak, M. A.

    1982-01-01

    Postinstability of fluids is eliminated in numerical models by introducing multivalued velocity fields after discarding the principle of impenetrability. Smooth functions are shown to be incapable of keeping the derivatives from going towards infinity when iterating solutions for the governing equations such as those defined by Navier-Stokes. Enlarging the class of functions is shown to be necessary to eliminate the appearance of imaginary characteristic roots in the systems of arbitrary partial differential equations, a condition which leads to physically impossible motions. The enlarging is demonstrated to be achievable by allowing several individual particles with different velocities to appear at the same point of space, and the subsequent multivaluedness of the solutions is purely a mathematical concern, rather than one of actual physical existence. Applications are provided for an inviscid fluid and for turbulence.

  7. Micronization processes with supercritical fluids: fundamentals and mechanisms.

    PubMed

    Martín, A; Cocero, M J

    2008-02-14

    Supercritical fluid techniques for materials precipitation have been proposed as an alternative to conventional precipitation processes as they allow to improve the performance of these processes in terms of reduction of particle size and control of morphology and particle size distribution, without degradation or contamination of the product. These techniques have received much attention during the last years, and their feasibility and performance have been experimentally demonstrated for many substances. One of the main pending tasks is the development of a systematic procedure for the design and scale-up of these processes. This requires not only empirical knowledge, but also information about the fundamentals of the process. This work aims to review the published literature dealing with a fundamental investigation or modeling of supercritical fluid precipitation processes.

  8. Mechanisms of Fluid-Mud Interactions Under Waves

    DTIC Science & Technology

    2006-01-01

    can be modeled as a constant, Bingham plastic with viscosity regularization, or a general Herschel-Bulkley fluid. The implementation of an implicit...results to SWAN simulations. He found that the wave attenuation in periods with moderate waves and low wind was fairly well described with friction ... factors that are typical of rippled sandy sea floors. He also found that in periods with stronger winds the spectral energy balance was sensitive

  9. Fluid mechanics, acoustics, and design of turbomachinery, part 2

    NASA Technical Reports Server (NTRS)

    Lakshminarayana, B. (Editor); Britsch, W. R. (Editor); Gearhart, W. S. (Editor)

    1974-01-01

    A conference was conducted to investigate various parameters involved in the design of turbomachinery. The acoustic properties of compressor rotors at subsonic speeds are described to show the sources of sound in fluid flows and sound radiation from the rotors. The design criteria for turbomachinery are examined to show impeller design methods, transonic compressor technology, and blade selection for an axial flow compressor. Specific applications of turbomachinery used as pumps for aerospace applications and turbomachinery for marine propulsion are described.

  10. Comparing the mechanical properties of the porcine knee meniscus when hydrated in saline versus synovial fluid.

    PubMed

    Lakes, Emily H; Kline, Courtney L; McFetridge, Peter S; Allen, Kyle D

    2015-12-16

    As research progresses to find a suitable knee meniscus replacement, accurate in vitro testing becomes critical for feasibility and comparison studies of mechanical integrity. Within the knee, the meniscus is bathed in synovial fluid, yet the most common hydration fluid in laboratory testing is phosphate buffered saline (PBS). PBS is a relatively simple salt solution, while synovial fluid is a complex non-Newtonian fluid with multiple lubricating factors. As such, PBS may interact with meniscal tissue differently than synovial fluid, and thus, the hydration fluid may be an important factor in obtaining accurate results during in vitro testing. To evaluate these effects, medial porcine menisci were used to evaluate tissue mechanics in tension (n=11) and compression (n=15). In all tests, two samples from the same meniscus were taken, where one sample was hydrated in PBS and the other was hydrated in synovial fluid. Statistical analysis revealed no significant differences between the mean mechanical properties of samples tested in PBS compared to synovial fluid; however, compressive testing revealed the variability between samples was significantly reduced if samples were tested in synovial fluid. For example, the compressive Young׳s Modulus was 12.69±7.49MPa in PBS versus 12.34±4.27MPa in synovial fluid. These results indicate testing meniscal tissue in PBS will largely not affect the mean value of the mechanical properties, but performing compression testing in synovial fluid may provide more consistent results between samples and assist in reducing sample numbers in some experiments.

  11. Analytical and Numerical Studies of Several Fluid Mechanical Problems

    NASA Astrophysics Data System (ADS)

    Kong, D. L.

    2014-03-01

    In this thesis, three parts, each with several chapters, are respectively devoted to hydrostatic, viscous, and inertial fluids theories and applications. Involved topics include planetary, biological fluid systems, and high performance computing technology. In the hydrostatics part, the classical Maclaurin spheroids theory is generalized, for the first time, to a more realistic multi-layer model, establishing geometries of both the outer surface and the interfaces. For one of its astrophysical applications, the theory explicitly predicts physical shapes of surface and core-mantle-boundary for layered terrestrial planets, which enables the studies of some gravity problems, and the direct numerical simulations of dynamo flows in rotating planetary cores. As another application of the figure theory, the zonal flow in the deep atmosphere of Jupiter is investigated for a better understanding of the Jovian gravity field. An upper bound of gravity field distortions, especially in higher-order zonal gravitational coefficients, induced by deep zonal winds is estimated firstly. The oblate spheroidal shape of an undistorted Jupiter resulting from its fast solid body rotation is fully taken into account, which marks the most significant improvement from previous approximation based Jovian wind theories. High viscosity flows, for example Stokes flows, occur in a lot of processes involving low-speed motions in fluids. Microorganism swimming is such a typical case. A fully three dimensional analytic solution of incompressible Stokes equation is derived in the exterior domain of an arbitrarily translating and rotating prolate spheroid, which models a large family of microorganisms such as cocci bacteria. The solution is then applied to the magnetotactic bacteria swimming problem, and good consistency has been found between theoretical predictions and laboratory observations of the moving patterns of such bacteria under magnetic fields. In the analysis of dynamics of planetary

  12. FLUID MECHANICS AND TANKAGE DESIGN FOR LOW GRAVITY ENVIRONMENT

    DTIC Science & Technology

    tankage delivers only single-phase propellants. The requirements for feed systems of electric engines are described briefly. Also, the 1.85-second drop...direction of mass transfer in tapered tubes and liquid-vapor interface shapes in an annular space between concentric cylinders. Possible feed systems

  13. Contact mechanics for poroelastic, fluid-filled media, with application to cartilage.

    PubMed

    Persson, B N J

    2016-12-21

    I study a simple contact mechanics model for a poroelastic, fluid-filled solid squeezed against a rigid, randomly rough substrate. I study how the fluid is squeezed out from the interface, and how the area of contact, and the average interfacial separation, change with time. I present numerical results relevant for a human cartilage. I show that for a fluid filled poroelastic solid the probability of cavitation (and the related wear as the cavities implode), and dynamical scraping (defined below and in Hutt and Persson, J. Chem. Phys. 144, 124903 (2016)), may be suppressed by fluid flow from the poroelastic solid into the (roughness induced) interfacial gap between the solids.

  14. Contact mechanics for poroelastic, fluid-filled media, with application to cartilage

    NASA Astrophysics Data System (ADS)

    Persson, B. N. J.

    2016-12-01

    I study a simple contact mechanics model for a poroelastic, fluid-filled solid squeezed against a rigid, randomly rough substrate. I study how the fluid is squeezed out from the interface, and how the area of contact, and the average interfacial separation, change with time. I present numerical results relevant for a human cartilage. I show that for a fluid filled poroelastic solid the probability of cavitation (and the related wear as the cavities implode), and dynamical scraping (defined below and in Hutt and Persson, J. Chem. Phys. 144, 124903 (2016)), may be suppressed by fluid flow from the poroelastic solid into the (roughness induced) interfacial gap between the solids.

  15. Mechanical modulation of nascent stem cell lineage commitment in tissue engineering scaffolds.

    PubMed

    Song, Min Jae; Dean, David; Knothe Tate, Melissa L

    2013-07-01

    Taking inspiration from tissue morphogenesis in utero, this study tests the concept of using tissue engineering scaffolds as delivery devices to modulate emergent structure-function relationships at early stages of tissue genesis. We report on the use of a combined computational fluid dynamics (CFD) modeling, advanced manufacturing methods, and experimental fluid mechanics (micro-piv and strain mapping) for the prospective design of tissue engineering scaffold geometries that deliver spatially resolved mechanical cues to stem cells seeded within. When subjected to a constant magnitude global flow regime, the local scaffold geometry dictates the magnitudes of mechanical stresses and strains experienced by a given cell, and in a spatially resolved fashion, similar to patterning during morphogenesis. In addition, early markers of mesenchymal stem cell lineage commitment relate significantly to the local mechanical environment of the cell. Finally, by plotting the range of stress-strain states for all data corresponding to nascent cell lineage commitment (95% CI), we begin to "map the mechanome", defining stress-strain states most conducive to targeted cell fates. In sum, we provide a library of reference mechanical cues that can be delivered to cells seeded on tissue engineering scaffolds to guide target tissue phenotypes in a temporally and spatially resolved manner. Knowledge of these effects allows for prospective scaffold design optimization using virtual models prior to prototyping and clinical implementation. Finally, this approach enables the development of next generation scaffolds cum delivery devices for genesis of complex tissues with heterogenous properties, e.g., organs, joints or interface tissues such as growth plates.

  16. Mechanical Modulation of Nascent Stem Cell Lineage Commitment in Tissue Engineering Scaffolds

    PubMed Central

    Song, Min Jae; Dean, David; Tate, Melissa L. Knothe

    2013-01-01

    Taking inspiration from tissue morphogenesis in utero, this study tests the concept of using tissue engineering scaffolds as delivery devices to modulate emergent structure-function relationships at early stages of tissue genesis. We report on the use of a combined computational fluid dynamics (CFD) modeling, advanced manufacturing methods, and experimental fluid mechanics (micro-piv and strain mapping) for the prospective design of tissue engineering scaffold geometries that deliver spatially resolved mechanical cues to cells seeded within. When subjected to a constant magnitude global flow regime, the local scaffold geometry dictates the magnitudes of mechanical stresses and strains experienced by a given cell, and in a spatially resolved fashion, similar to patterning during morphogenesis. In addition, early markers of mesenchymal stem cell lineage commitment relate significantly to the local mechanical environment of the cell. Finally, by plotting the range of stress-strain states for all data corresponding to nascent cell lineage commitment (95% CI), we begin to “map the mechanome”, defining stress-strain states most conducive to targeted cell fates. In sum, we provide a library of reference mechanical cues that can be delivered to cells seeded on tissue engineering scaffolds to guide target tissue phenotypes in a temporally and spatially resolved manner. Knowledge of these effects allows for prospective scaffold design optimization using virtual models prior to prototyping and clinical implementation. Finally, this approach enables the development of next generation scaffolds cum delivery devices for genesis of complex tissues with heterogenous properties, e.g., organs, joints or interface tissues such as growth plates. PMID:23660249

  17. MECHANISMS OF FLUID SHEAR-INDUCED INHIBITION OF POPULATION GROWTH IN A RED-TIDE DINOFLAGELLATE

    EPA Science Inventory

    Net population growth of some dinoflagellates is inhibited by fluid shear at shear stresses comparable with those generated during oceanic turbulence. Decreased net growth may occur through lowered cell division, increased mortality, or both. The dominant mechanism under various ...

  18. Contact mechanics of reverse engineered distal humeral hemiarthroplasty implants.

    PubMed

    Willing, Ryan; King, Graham J W; Johnson, James A

    2015-11-26

    Erosion of articular cartilage is a concern following distal humeral hemiarthroplasty, because native cartilage surfaces are placed in contact with stiff metallic implant components, which causes decreases in contact area and increases in contact stresses. Recently, reverse engineered implants have been proposed which are intended to promote more natural contact mechanics by reproducing the native bone or cartilage shape. In this study, finite element modeling is used in order to calculate changes in cartilage contact areas and stresses following distal humeral hemiarthroplasty with commercially available and reverse engineered implant designs. At the ulna, decreases in contact area were -34±3% (p=0.002), -27±1% (p<0.001) and -14±2% (p=0.008) using commercially available, bone reverse engineered and cartilage reverse engineered designs, respectively. Peak contact stresses increased by 461±57% (p=0.008), 387±127% (p=0.229) and 165±16% (p=0.003). At the radius, decreases in contact area were -21±3% (p=0.013), -13±2% (p<0.006) and -6±1% (p=0.020), and peak contact stresses increased by 75±52% (p>0.999), 241±32% (p=0.010) and 61±10% (p=0.021). Between the three different implant designs, the cartilage reverse engineered design yielded the largest contact areas and lowest contact stresses, but was still unable to reproduce the contact mechanics of the native joint. These findings align with a growing body of evidence indicating that although reverse engineered hemiarthroplasty implants can provide small improvements in contact mechanics when compared with commercially available designs, further optimization of shape and material properties is required in order reproduce native joint contact mechanics.

  19. Engine Fundamentals: Automotive Mechanics Instructional Program. Block 2.

    ERIC Educational Resources Information Center

    O'Brien, Ralph D.

    The second of six instructional blocks in automotive mechanics, the lessons and supportive information in the document provide a guide for teachers in planning an instructional program in engine fundamentals at the secondary and postsecondary level. The material, as organized, is a suggested sequence of instruction within each block. Each lesson…

  20. Evaluating Risk Awareness in Undergraduate Students Studying Mechanical Engineering

    ERIC Educational Resources Information Center

    Langdon, G. S.; Balchin, K.; Mufamadi, P.

    2010-01-01

    This paper examines the development of risk awareness among undergraduate students studying mechanical engineering at a South African university. A questionnaire developed at the University of Liverpool was modified and used on students from the first, second and third year cohorts to assess their awareness in the areas of professional…

  1. Basic Gasoline Engine Mechanics. Florida Vocational Program Guide.

    ERIC Educational Resources Information Center

    University of South Florida, Tampa. Dept. of Adult and Vocational Education.

    This packet contains a program guide and Career Merit Achievement Plan (Career MAP) for the implementation of a basic gasoline engine mechanics program in Florida secondary and postsecondary schools. The program guide describes the program content and structure, provides a program description, lists job titles under the program, and includes a…

  2. Structural and vascular analysis of tissue engineering scaffolds, Part 1: Numerical fluid analysis.

    PubMed

    Almeida, Henrique A; Bártolo, Paulo J

    2012-01-01

    Rapid prototyping technologies were recently introduced in the medical field, being particularly viable to produce porous scaffolds for tissue engineering. These scaffolds should be biocompatible, biodegradable, with appropriate porosity, pore structure, and pore distribution on top of presenting both surface and structural compatibility. This chapter presents the state-of-the-art in tissue engineering and scaffold design using numerical fluid analysis for optimal vascular design. The vascularization of scaffolds is an important aspect due to its influence regarding the normal flow of biofluids within the human body. This computational tool also allows to design either a scaffold offering less resistance to the normal flow of biofluids or reducing the possibility for blood coagulation through forcing the flow toward a specific direction.

  3. Development and Use of Engineering Standards for Computational Fluid Dynamics for Complex Aerospace Systems

    NASA Technical Reports Server (NTRS)

    Lee, Hyung B.; Ghia, Urmila; Bayyuk, Sami; Oberkampf, William L.; Roy, Christopher J.; Benek, John A.; Rumsey, Christopher L.; Powers, Joseph M.; Bush, Robert H.; Mani, Mortaza

    2016-01-01

    Computational fluid dynamics (CFD) and other advanced modeling and simulation (M&S) methods are increasingly relied on for predictive performance, reliability and safety of engineering systems. Analysts, designers, decision makers, and project managers, who must depend on simulation, need practical techniques and methods for assessing simulation credibility. The AIAA Guide for Verification and Validation of Computational Fluid Dynamics Simulations (AIAA G-077-1998 (2002)), originally published in 1998, was the first engineering standards document available to the engineering community for verification and validation (V&V) of simulations. Much progress has been made in these areas since 1998. The AIAA Committee on Standards for CFD is currently updating this Guide to incorporate in it the important developments that have taken place in V&V concepts, methods, and practices, particularly with regard to the broader context of predictive capability and uncertainty quantification (UQ) methods and approaches. This paper will provide an overview of the changes and extensions currently underway to update the AIAA Guide. Specifically, a framework for predictive capability will be described for incorporating a wide range of error and uncertainty sources identified during the modeling, verification, and validation processes, with the goal of estimating the total prediction uncertainty of the simulation. The Guide's goal is to provide a foundation for understanding and addressing major issues and concepts in predictive CFD. However, this Guide will not recommend specific approaches in these areas as the field is rapidly evolving. It is hoped that the guidelines provided in this paper, and explained in more detail in the Guide, will aid in the research, development, and use of CFD in engineering decision-making.

  4. Movement of geothermal fluid in the Cerro Prieto field as determined from well log and reservoir engineering data

    SciTech Connect

    Halfman, S.E.; Lippmann, M.J.; Zelwer, R.

    1982-01-01

    A hydrogeologic model of the Cerro Prieto geothermal field in its undisturbed state, developed on the basis of well log and reservoir engineering data, is discussed. According to this model, geothermal fluid enters the field from the east through a deep (>10,000 ft) sandstone aquifer which is overlain by a thick shale unit which locally prevents the upward migration of the fluid. As it flows westward, the fluid gradually rises through faults and sandy gaps in the shale unit. Eventually, some of the fluid leaks to the surface in the western part of the field, while the rest mixes with surrounding colder waters.

  5. Ongoing Analysis of Rocket Based Combined Cycle Engines by the Applied Fluid Dynamics Analysis Group at Marshall Space Flight Center

    NASA Technical Reports Server (NTRS)

    Ruf, Joseph; Holt, James B.; Canabal, Francisco

    1999-01-01

    This paper presents the status of analyses on three Rocket Based Combined Cycle configurations underway in the Applied Fluid Dynamics Analysis Group (TD64). TD64 is performing computational fluid dynamics analysis on a Penn State RBCC test rig, the proposed Draco axisymmetric RBCC engine and the Trailblazer engine. The intent of the analysis on the Penn State test rig is to benchmark the Finite Difference Navier Stokes code for ejector mode fluid dynamics. The Draco engine analysis is a trade study to determine the ejector mode performance as a function of three engine design variables. The Trailblazer analysis is to evaluate the nozzle performance in scramjet mode. Results to date of each analysis are presented.

  6. Mechanism of Headward Fluid Shift During Exposure To Microgravity

    NASA Technical Reports Server (NTRS)

    Hargens, Alan R.; Parazynski, Scott E.; Watenpaugh, Donald E.; Aratow, Michael; Murthy, Gita; Kawai, Yasuaki

    1994-01-01

    A prominent feature of early cardiovascular adaptation to the microgravity of space flight is a shift of blood and tissue fluid from the lower body to the upper body. Symptoms of this fluid shift include facial edema, nasal congestion, and headache. Normally on Earth, the human body is exposed to hydrostatic (gravitational) blood pressure gradients during upright posture. In this posture, mean arterial pressures at head, heart, and foot levels are approximately 70, 100, and 200 mm Hg, respectively. Theoretically, all hydrostatic pressures within arteries and veins are lost during exposure to microgravity so that mean arterial pressure in all regions of the body is uniform and approximately equal to that at heart level (100 mm Hg). Acute studies of 60 head-down tilt (simulated microgravity on Earth) indicate that facial edema is caused by: 1) elevation of capillary blood pressure from 28 to 34 mm Hg, 2) reduction of blood colloid osmotic pressure 22 to 18 mm Hg, and 3) 50% increase of blood perfusion in tissues of the head. Furthermore, as compared to microvasculature in the feet, microvessels of the head have a low capacity to constrict and diminish local perfusion. Elevation of blood and tissue fluid pressures/flow in the head may also explain the higher headward bone density associated with long-term head-down tilt. These mechanistic studies of head-down tilt, along with a better understanding of the relative stresses involved with upright posture and lower body negative pressure, have facilitated development of physiologic countermeasures to maintain astronaut health during microgravity. Presently no exercise hardware is available to provide a blood pressure gradient from head to feet in space. However, recent studies in our laboratory suggest that treadmill exercise within lower body negative pressure provides equivalent or greater physiologic stress as compared to similar upright exercise on Earth.

  7. Use of piezoelectric multicomponent force measuring devices in fluid mechanics

    NASA Technical Reports Server (NTRS)

    Richter, A.; Stefan, K.

    1979-01-01

    The characterisitics of piezoelectric multicomponent transducers are discussed, giving attention to the advantages of quartz over other materials. The main advantage of piezoelectric devices in aerodynamic studies is their ability to indicate rapid changes in the values of physical parameters. Problems in the accuracy of measurments by piezoelectric devices can be overcome by suitable design approaches. A practical example is given of how such can be utilized to measure rapid fluctuations of fluid forces exerted on a circular cylinder mounted in a water channel.

  8. Crystal Growth and Fluid Mechanics Problems in Directional Solidification

    NASA Technical Reports Server (NTRS)

    Tanveer, Saleh A.; Baker, Gregory R.; Foster, Michael R.

    2001-01-01

    Our work in directional solidification has been in the following areas: (1) Dynamics of dendrites including rigorous mathematical analysis of the resulting equations; (2) Examination of the near-structurally unstable features of the mathematically related Hele-Shaw dynamics; (3) Numerical studies of steady temperature distribution in a vertical Bridgman device; (4) Numerical study of transient effects in a vertical Bridgman device; (5) Asymptotic treatment of quasi-steady operation of a vertical Bridgman furnace for large Rayleigh numbers and small Biot number in 3D; and (6) Understanding of Mullins-Sererka transition in a Bridgman device with fluid dynamics is accounted for.

  9. Design of a new engine mount for vertical and horizontal vibration control using magnetorheological fluid

    NASA Astrophysics Data System (ADS)

    Phu, D. X.; Choi, S. B.; Lee, Y. S.; Han, M. S.

    2014-10-01

    This paper presents a new design of a magnetorheological fluid (MR) mount for vibration control considering both vertical forces and horizontal moments such as are met in various engine systems, including a medium high-speed engine of ship. The newly designed mount, called a MR brake mount, offers several salient benefits such as small size and relatively high load capacity compared with a conventional MR engine mount that can control vertical vibration only. The principal design parameters of the proposed mount are optimally determined to achieve maximum torque with geometric and spatial constraints. Subsequently, the proposed MR mount is designed and manufactured based on the optimized design parameters. It is shown from experimental testing that the proposed mount, which combines MR mount with MR brake, can produce the desired force and torque to reduce unwanted vibration of a medium high-speed engine system of ship subjected to both vertical and horizontal exciting motions. In addition, it is verified that there is no large difference between experiment results and simulation results that are obtained from an analytical model derived in this work.

  10. Error Estimation and Uncertainty Propagation in Computational Fluid Mechanics

    NASA Technical Reports Server (NTRS)

    Zhu, J. Z.; He, Guowei; Bushnell, Dennis M. (Technical Monitor)

    2002-01-01

    Numerical simulation has now become an integral part of engineering design process. Critical design decisions are routinely made based on the simulation results and conclusions. Verification and validation of the reliability of the numerical simulation is therefore vitally important in the engineering design processes. We propose to develop theories and methodologies that can automatically provide quantitative information about the reliability of the numerical simulation by estimating numerical approximation error, computational model induced errors and the uncertainties contained in the mathematical models so that the reliability of the numerical simulation can be verified and validated. We also propose to develop and implement methodologies and techniques that can control the error and uncertainty during the numerical simulation so that the reliability of the numerical simulation can be improved.

  11. Experience revising an advanced-undergraduate/beginning-graduate fluid mechanics textbook

    NASA Astrophysics Data System (ADS)

    Dowling, David

    2012-11-01

    In the fall of 2009, Elsevier Inc. approached me about taking over as the lead author of the fluid mechanics textbook by P. K. Kundu and I. M. Cohen. I subsequently agreed and this presentation provides the story of the process and the approach taken to revising this fluid mechanics textbook which has been in print for approximately 15 years. The goal of the revision was to produce an excellent textbook for second courses in fluid mechanics taken by advanced undergraduate and beginning graduate students while maintaining the book's appeal to instructors who used prior editions. Thus, I sought to maintain or expand the text's fluid mechanics content, while adjusting the text's tone so that this content might be more readily reached by students who may have had only one prior course in fluid mechanics, or who may not specialize in fluid mechanics but do possess appropriate mathematical skills. The entire revision process involved seven steps: (i) formulating a revision plan that was independently reviewed, (ii) agreeing to a formal contract with deadlines, (iii) revising the text, figures, and front matter, (iv) proof reading and correcting copy-edited text, (v) correcting page proofs, (vi) generating the solutions manual, and (vii) tabulating errata. Formulating and executing the

  12. Fluid Mechanics and Heat Transfer Spirally Fluted Tubing.

    DTIC Science & Technology

    1984-12-01

    on a flat strip and subsequently welding the corregated strip to form spiral fluted tubing results in a low fabrication cost approximately equal to...G., "Intensification of Convective Heat Exchange by Spiral Swirlers in the Flow of Anomalously Viscous Liquid in Pipes ", Journal of Engineering...axial velocity at the pipe axis w (V w ( velocity components in the (Z ( z ,(Z)) co-ordinate system x x x ( co-ordinate system following the spiralling Of

  13. Adaptive Local Grid Refinement in Computational Fluid Mechanics.

    DTIC Science & Technology

    1987-11-01

    Adaptive mesh refinements in reservoir simulation applications (R.E. Ew- ing), Proceedings Intl. Conference on Accuracy Est. and Adaptive Refine... reservoir simulation (R.E. Ewing and .J.V. 1{oebbe), Innovati’ve Numerical Mlethods in Engineering, (R.P. Shaw, J. Pc- riaux, A. Chaudouet, J. Wu...Universities, Cheyenne, Wyoming, February 21, 1986, O 9. Finite element techniques for reservoir simulation , Fourth International Sym- posium on Numerical

  14. Comparison of Venous Return Characteristics with Right Ventricular Mechanics During Cephalic Fluid Shift

    NASA Technical Reports Server (NTRS)

    Elliott, Morgan; Martin, David

    2015-01-01

    For my summer internship project, I organized a pilot study to analyze the effects of a cephalic fluid shift on venous return and right ventricular mechanics to increase right ventricular and venous knowledge. To accomplish this pilot study, I wrote a testing protocol, obtained Institutional Review Board (IRB) approval, completed subject payment forms, lead testing sessions, and analyzed the data. This experiment used -20deg head down tilt (20 HDT) as the ground based simulation for the fluid shift that occurs during spaceflight and compared it to data obtained from the seated and supine positions. Using echocardiography, data was collected for the right ventricle, hepatic vein, internal jugular vein, external jugular vein, and inferior vena cava. Additionally, non-invasive venous pressure measurements, similar to those soon to be done in-orbit, were collected. It was determined that the venous return from below the heard is increased during 20 HDT, which was supported by increased hepatic vein velocities, increased right ventricular inflow, and increased right ventricular strain at 20 HDT relative to seated values. Jugular veins in the neck undergo an increase in pressure and area, but no significant increase in flow, relative to seated values when a subject is tilted 20 HDT. Contrary to the initial expectations based on this jugular flow, there was no significant increase in central venous pressure, as evidenced by no change in Doppler indices for right arterial pressure or inferior vena cava diameter. It is suspected that these differences in pressure are due to the hydrostatic pressure indifference point shifting during tilt; there is a potential for a similar phenomenon with microgravity. This data will hopefully lead to a more in-depth understanding of the response of the body to microgravity and how those relate to the previously mentioned cardiovascular risk of fluid shift that is associated with spaceflight. These results were presented in greater detail

  15. Thermophysical property data - Who needs them. [similarity principle applications in fluid mechanics and heat transfer

    NASA Technical Reports Server (NTRS)

    Hendricks, R. C.

    1979-01-01

    Specific examples are cited herein to illustrate the universal needs and demands for thermophysical property data. Applications of the principle of similarity in fluid mechanics and heat transfer and extensions of the principle to fluid mixtures are discussed. It becomes quite clear that no matter how eloquent theories or experiments in fluid mechanics or heat transfer are, the results of their application can be no more accurate than the thermophysical properties required to transform these theories into practice, or in the case of an experiment, to reduce the data. Present-day projects take place on such a scale that the need for international standards and mutual cooperation is evident.

  16. GEORGE KEITH BATCHELOR 8 March 1920 30 March 2000 Founding Editor, Journal of Fluid Mechanics, 1956

    NASA Astrophysics Data System (ADS)

    Huppert, Herbert E.

    2000-10-01

    George Batchelor was one of the giants of fluid mechanics in the second half of the twentieth century. He had a passion for physical and quantitative understanding of fluid flows and a single-minded determination that fluid mechanics should be pursued as a subject in its own right. He once wrote that he ‘spent a lifetime happily within its boundaries’. Six feet tall, thin and youthful in appearance, George's unchanging attire and demeanour contrasted with his ever-evolving scientific insights and contributions. His strongly held and carefully articulated opinions, coupled with his forthright objectivity, shone through everything he undertook.

  17. The mechanical response in a fluid of synthetic antiferromagnetic and ferrimagnetic microdiscs with perpendicular magnetic anisotropy.

    PubMed

    Vemulkar, T; Welbourne, E N; Mansell, R; Petit, D C M C; Cowburn, R P

    2017-01-23

    In this article, we demonstrate the magneto-mechanic behavior in a fluid environment of perpendicularly magnetized microdiscs with antiferromagnetic interlayer coupling. When suspended in a fluid and under the influence of a simple uniaxial applied magnetic field sequence, the microdiscs mechanically rotate to access the magnetic saturation processes that are either that of the easy axis, hard axis, or in-between the two, in order to lower their energy. Further, these transitions enable the magnetic particles to form reconfigurable magnetic chains, and transduce torque from uniaxial applied fields. These microdiscs offer an attractive platform for the fabrication of fluid based micro- and nanodevices, and dynamically self assembled complex architectures.

  18. The mechanical response in a fluid of synthetic antiferromagnetic and ferrimagnetic microdiscs with perpendicular magnetic anisotropy

    PubMed Central

    Vemulkar, T.; Welbourne, E. N.; Petit, D. C. M. C.; Cowburn, R. P.

    2017-01-01

    In this article, we demonstrate the magneto-mechanic behavior in a fluid environment of perpendicularly magnetized microdiscs with antiferromagnetic interlayer coupling. When suspended in a fluid and under the influence of a simple uniaxial applied magnetic field sequence, the microdiscs mechanically rotate to access the magnetic saturation processes that are either that of the easy axis, hard axis, or in-between the two, in order to lower their energy. Further, these transitions enable the magnetic particles to form reconfigurable magnetic chains, and transduce torque from uniaxial applied fields. These microdiscs offer an attractive platform for the fabrication of fluid based micro- and nanodevices, and dynamically self assembled complex architectures. PMID:28190886

  19. The mechanical response in a fluid of synthetic antiferromagnetic and ferrimagnetic microdiscs with perpendicular magnetic anisotropy

    NASA Astrophysics Data System (ADS)

    Vemulkar, T.; Welbourne, E. N.; Mansell, R.; Petit, D. C. M. C.; Cowburn, R. P.

    2017-01-01

    In this article, we demonstrate the magneto-mechanic behavior in a fluid environment of perpendicularly magnetized microdiscs with antiferromagnetic interlayer coupling. When suspended in a fluid and under the influence of a simple uniaxial applied magnetic field sequence, the microdiscs mechanically rotate to access the magnetic saturation processes that are either that of the easy axis, hard axis, or in-between the two, in order to lower their energy. Further, these transitions enable the magnetic particles to form reconfigurable magnetic chains, and transduce torque from uniaxial applied fields. These microdiscs offer an attractive platform for the fabrication of fluid based micro- and nanodevices, and dynamically self assembled complex architectures.

  20. Electroresponsive Aqueous Silk Protein As “Smart” Mechanical Damping Fluid

    PubMed Central

    2015-01-01

    Here we demonstrate the effectiveness of an electroresponsive aqueous silk protein polymer as a smart mechanical damping fluid. The aqueous polymer solution is liquid under ambient conditions, but is reversibly converted into a gel once subjected to an electric current, thereby increasing or decreasing in viscosity. This nontoxic, biodegradable, reversible, edible fluid also bonds to device surfaces and is demonstrated to reduce friction and provide striking wear protection. The friction and mechanical damping coefficients are shown to modulate with electric field exposure time and/or intensity. Damping coefficient can be modulated electrically, and then preserved without continued power for longer time scales than conventional “smart” fluid dampers. PMID:24750065

  1. Mechanotransduction in bone: osteoblasts are more responsive to fluid forces than mechanical strain

    NASA Technical Reports Server (NTRS)

    Owan, I.; Burr, D. B.; Turner, C. H.; Qiu, J.; Tu, Y.; Onyia, J. E.; Duncan, R. L.

    1997-01-01

    Mechanical force applied to bone produces two localized mechanical signals on the cell: deformation of the extracellular matrix (substrate strain) and extracellular fluid flow. To study the effects of these stimuli on osteoblasts, MC3T3-E1 cells were grown on type I collagen-coated plastic plates and subjected to four-point bending. This technique produces uniform levels of physiological strain and fluid forces on the cells. Each of these parameters can be varied independently. Osteopontin (OPN) mRNA expression was used to assess the anabolic response of MC3T3-E1 cells. When fluid forces were low, neither strain magnitude nor strain rate was correlated with OPN expression. However, higher-magnitude fluid forces significantly increased OPN message levels independently of the strain magnitude or rate. These data indicate that fluid forces, and not mechanical stretch, influence OPN expression in osteoblasts and suggest that fluid forces induced by extracellular fluid flow within the bone matrix may play an important role in bone formation in response to mechanical loading.

  2. A review of interaction mechanisms in fluid-solid flows

    SciTech Connect

    Johnson, G.; Rajagopal, K.R. . Dept. of Mechanical Engineering); Massoudi, M. )

    1990-09-01

    Multiphase flows have become the subject of considerable attention because of their importance in many industrial applications, such as fluidized beds, pneumatic transport of solids, coal combustion, etc. Fundamental research into the nature of pneumatic transport has made significant progress in identifying key parameters controlling the characteristics of these processes. The emphasis of this study is on a mixture composed of spherical particles of uniform size and a linearly viscous fluid. Section 1 introduces our approach and the importance of this study. In Section 2, the dynamics of a single particle as studied in classical hydrodynamics and fluid dynamics is presented. This has been a subject of study for more than 200 years. In Section 3, we review the literature for the constitutive relations as given in multiphase studies, i.e., generalization of single particle and as given in literature concerning the continuum theories of mixtures or multicomponent systems. In Section 4, a comparison between these representations and the earlier approach, i.e., forces acting on a single particle will be made. The importance of flow regimes, particle concentration, particle size and shape, rotation of the particle, effect of solid walls, etc. are discussed. 141 refs.

  3. Experiments and Modeling of G-Jitter Fluid Mechanics

    NASA Technical Reports Server (NTRS)

    Leslie, F. W.; Ramachandran, N.; Whitaker, Ann F. (Technical Monitor)

    2002-01-01

    While there is a general understanding of the acceleration environment onboard an orbiting spacecraft, past research efforts in the modeling and analysis area have still not produced a general theory that predicts the effects of multi-spectral periodic accelerations on a general class of experiments nor have they produced scaling laws that a prospective experimenter can use to assess how an experiment might be affected by this acceleration environment. Furthermore, there are no actual flight experimental data that correlates heat or mass transport with measurements of the periodic acceleration environment. The present investigation approaches this problem with carefully conducted terrestrial experiments and rigorous numerical modeling for better understanding the effect of residual gravity and gentler on experiments. The approach is to use magnetic fluids that respond to an imposed magnetic field gradient in much the same way as fluid density responds to a gravitational field. By utilizing a programmable power source in conjunction with an electromagnet, both static and dynamic body forces can be simulated in lab experiments. The paper provides an overview of the technique and includes recent results from the experiments.

  4. The instanton method and its numerical implementation in fluid mechanics

    NASA Astrophysics Data System (ADS)

    Grafke, Tobias; Grauer, Rainer; Schäfer, Tobias

    2015-08-01

    A precise characterization of structures occurring in turbulent fluid flows at high Reynolds numbers is one of the last open problems of classical physics. In this review we discuss recent developments related to the application of instanton methods to turbulence. Instantons are saddle point configurations of the underlying path integrals. They are equivalent to minimizers of the related Freidlin-Wentzell action and known to be able to characterize rare events in such systems. While there is an impressive body of work concerning their analytical description, this review focuses on the question on how to compute these minimizers numerically. In a short introduction we present the relevant mathematical and physical background before we discuss the stochastic Burgers equation in detail. We present algorithms to compute instantons numerically by an efficient solution of the corresponding Euler-Lagrange equations. A second focus is the discussion of a recently developed numerical filtering technique that allows to extract instantons from direct numerical simulations. In the following we present modifications of the algorithms to make them efficient when applied to two- or three-dimensional (2D or 3D) fluid dynamical problems. We illustrate these ideas using the 2D Burgers equation and the 3D Navier-Stokes equations.

  5. Mechanical stimulation in the engineering of heart muscle.

    PubMed

    Liaw, Norman Yu; Zimmermann, Wolfram-Hubertus

    2016-01-15

    Recreating the beating heart in the laboratory continues to be a formidable bioengineering challenge. The fundamental feature of the heart is its pumping action, requiring considerable mechanical forces to compress a blood filled chamber with a defined in- and outlet. Ventricular output crucially depends on venous loading of the ventricles (preload) and on the force generated by the preloaded ventricles to overcome arterial blood pressure (afterload). The rate of contraction is controlled by the spontaneously active sinus node and transmission of its electrical impulses into the ventricles. The underlying principles for these physiological processes are described by the Frank-Starling mechanism and Bowditch phenomenon. It is essential to consider these principles in the design and evaluation of tissue engineered myocardium. This review focuses on current strategies to evoke mechanical loading in hydrogel-based heart muscle engineering.

  6. Fracture mechanics criteria for turbine engine hot section components

    NASA Technical Reports Server (NTRS)

    Meyers, G. J.

    1982-01-01

    The application of several fracture mechanics data correlation parameters to predicting the crack propagation life of turbine engine hot section components was evaluated. An engine survey was conducted to determine the locations where conventional fracture mechanics approaches may not be adequate to characterize cracking behavior. Both linear and nonlinear fracture mechanics analyses of a cracked annular combustor liner configuration were performed. Isothermal and variable temperature crack propagation tests were performed on Hastelloy X combustor liner material. The crack growth data was reduced using the stress intensity factor, the strain intensity factor, the J integral, crack opening displacement, and Tomkins' model. The parameter which showed the most effectiveness in correlation high temperature and variable temperature Hastelloy X crack growth data was crack opening displacement.

  7. Mechanisms of mechanosensing - mechanosensitive channels, function and re-engineering.

    PubMed

    Kocer, Armagan

    2015-12-01

    Sensing and responding to mechanical stimuli is an ancient behavior and ubiquitous to all forms of life. One of its players 'mechanosensitive ion channels' are involved in processes from osmosensing in bacteria to pain in humans. However, the mechanism of mechanosensing is yet to be elucidated. This review describes recent developments in the understanding of a bacterial mechanosensitive channel. Force from the lipid principle of mechanosensation, new methods to understand protein-lipid interactions, the role of water in the gating, the use of engineered mechanosensitive channels in the understanding of the gating mechanism and application of the accumulated knowledge in the field of drug delivery, drug design and sensor technologies are discussed.

  8. Methodological advances in predicting flow-induced dynamics of plants using mechanical-engineering theory.

    PubMed

    de Langre, Emmanuel

    2012-03-15

    The modeling of fluid-structure interactions, such as flow-induced vibrations, is a well-developed field of mechanical engineering. Many methods exist, and it seems natural to apply them to model the behavior of plants, and potentially other cantilever-like biological structures, under flow. Overcoming this disciplinary divide, and the application of such models to biological systems, will significantly advance our understanding of ecological patterns and processes and improve our predictive capabilities. Nonetheless, several methodological issues must first be addressed, which I describe here using two practical examples that have strong similarities: one from agricultural sciences and the other from nuclear engineering. Very similar issues arise in both: individual and collective behavior, small and large space and time scales, porous modeling, standard and extreme events, trade-off between the surface of exchange and individual or collective risk of damage, variability, hostile environments and, in some aspects, evolution. The conclusion is that, although similar issues do exist, which need to be exploited in some detail, there is a significant gap that requires new developments. It is obvious that living plants grow in and adapt to their environment, which certainly makes plant biomechanics fundamentally distinct from classical mechanical engineering. Moreover, the selection processes in biology and in human engineering are truly different, making the issue of safety different as well. A thorough understanding of these similarities and differences is needed to work efficiently in the application of a mechanistic approach to ecology.

  9. Reverse engineering systems models of regulation: discovery, prediction and mechanisms.

    PubMed

    Ashworth, Justin; Wurtmann, Elisabeth J; Baliga, Nitin S

    2012-08-01

    Biological systems can now be understood in comprehensive and quantitative detail using systems biology approaches. Putative genome-scale models can be built rapidly based upon biological inventories and strategic system-wide molecular measurements. Current models combine statistical associations, causative abstractions, and known molecular mechanisms to explain and predict quantitative and complex phenotypes. This top-down 'reverse engineering' approach generates useful organism-scale models despite noise and incompleteness in data and knowledge. Here we review and discuss the reverse engineering of biological systems using top-down data-driven approaches, in order to improve discovery, hypothesis generation, and the inference of biological properties.

  10. 9. Photographic copy of engineering drawing showing the mechanical layout ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. Photographic copy of engineering drawing showing the mechanical layout of Test Stand 'C' Cv Cell, vacuum line, and scrubber-condenser as erected in 1977-78. JPL drawing by VTN Consolidated, Inc. Engineers, Architects, Planners, 2301 Campus Drive, Irvine, California 92664: 'JPL-ETS E-18 (C-Stand Modifications) Control Elevations & Schematics,' sheet M-5 (JPL sheet number E18/44-0), 1 September 1977. - Jet Propulsion Laboratory Edwards Facility, Test Stand C, Edwards Air Force Base, Boron, Kern County, CA

  11. Valve operating and interrupting mechanism for internal combustion engine

    SciTech Connect

    Ajiki, Y.; Kajiwara, S.

    1986-09-23

    A valve operating mechanism is described for an internal combustion engine having a pair of intake or exhaust valves for each engine cylinder, comprising, a camshaft having high speed and low speed cams thereon, a rocker arm shaft having first second and third rocker arms pivotally mounted thereon in mutually adjacent relationship. The first and third rocker arms engage pair of valves, the first and second rocker arms engaging the low speed and high speed cams, respectively. The piston means in the rocker arms is electively shiftable between positions connecting the rocker arms for pivotal movement in unison and disconnecting the rocker arms for independent movement.

  12. Valve timing adjusting mechanism for internal combustion engine for adjusting timing of intake valve and/or exhaust valve corresponding to engine operating conditions

    SciTech Connect

    Akassaka, A.; Suga, S.; Sawada, T.

    1989-03-14

    A valve timing adjusting mechanism for an internal combustion engine is described, comprising: a camshaft carrying a cam for driving one of an intake valve and an exhaust valve, the camshaft having a section formed with first helical gear teeth; a cam pulley engaging a timing belt driven by the engine for rotation in synchronism with engine revolution, the cam pulley having second helical gear teeth; a ring gear having inner and outer helical gear teeth engageable with the first and second gear teeth of the camshaft and the cam pulley; first means for defining an enclosed chamber facing one planar face of the ring gear and connected with a fluid pressure source to receive pressurized fluid therefrom; a spring means associated with the other planar face of the ring gear for exerting an initial biasing force on the ring gear in opposition to the force due to the pressure on the ring gear from the enclosed chamber; and second means for controlling the fluid pressure introduced into the enclosed chamber in accordance with engine operating conditions so as to shift the ring gear between two positions.

  13. Investigation of thermal-fluid mechanical characteristics of the capillary pump and the pumped two-phase loop

    NASA Technical Reports Server (NTRS)

    Kiper, Ali M.

    1987-01-01

    This first semi-annual report summarized progress made on NASA Goddard Space Flight Center (GSFC) Grant NAG 5-834 during the period September 1, 1986 to February 28, 1987. The goal of the project is to gain a better understanding of the transient behavior of the Capillary Pump Loop (CPL) developed and tested by the GSFC. The investigation is directed toward development of analytical models to represent the transient thermal-fluid mechanic processes occurring in different parts of the CPL engineering model. Evaluation of the available test data has been the starting point for the investigation. Based on results of this evaluation, supplementary tests will be conducted by using a CPL test system already operational in the Heat Transfer laboratory of the university. Of particular interest is the oscillatory behavior of the CPL engineering model exhibited during some of the earlier test runs conducted at NASA-GSFC and Johnson Space Center (JSC).

  14. Summer Work Experience: Determining Methane Combustion Mechanisms and Sub-Scale Diffuser Properties for Space Transporation System Engine Testing

    NASA Technical Reports Server (NTRS)

    Williams, Powtawche N.

    1998-01-01

    To assess engine performance during the testing of Space Shuttle Main Engines (SSMEs), the design of an optimal altitude diffuser is studied for future Space Transportation Systems (STS). For other Space Transportation Systems, rocket propellant using kerosene is also studied. Methane and dodecane have similar reaction schemes as kerosene, and are used to simulate kerosene combustion processes at various temperatures. The equations for the methane combustion mechanism at high temperature are given, and engine combustion is simulated on the General Aerodynamic Simulation Program (GASP). The successful design of an altitude diffuser depends on the study of a sub-scaled diffuser model tested through two-dimensional (2-D) flow-techniques. Subroutines given calculate the static temperature and pressure at each Mach number within the diffuser flow. Implementing these subroutines into program code for the properties of 2-D compressible fluid flow determines all fluid characteristics, and will be used in the development of an optimal diffuser design.

  15. Using reverse engineering and computational fluid dynamics to investigate a lower arm amputee swimmer's performance.

    PubMed

    Lecrivain, Gregory; Slaouti, Arezki; Payton, Carl; Kennedy, Ian

    2008-09-18

    In front crawl swimming, the hand and the corresponding forearm generate major propulsive forces. Such forces have been studied largely through experimental tests and more recently through the use of steady computational fluid dynamics (CFD). However, the effect of the upper arm on the propulsive forces has generally not been taken into consideration. An understanding of such forces is fundamental for the performance of swimmers who have an arm amputation at the level of the elbow. This study introduces the great potential offered by the multidisciplinary approach combining reverse engineering and unsteady CFD in a novel dynamic and interactive way. A complex CFD mesh model, representing the swimmer body and its upper arm, is produced. The model, including the arm rotation and a body roll movement, interacts dynamically with the fluid flow. Forces generated by the upper arm can then be investigated in great detail. In this particular study, it is found that the upper arm effectively contributes to the propulsion of the body. The propulsive force was numerically computed throughout the pull and reaches maxima of 8 N. Results obtained in this study could be extended in a similar way to any other limb movement within a fluid flow.

  16. Atomization and dense-fluid breakup regimes in liquid rocket engines

    DOE PAGES

    Oefelein, Joseph; Dahms, Rainer Norbert Uwe

    2015-04-20

    Until recently, modern theory has lacked a fundamentally based model to predict the operating pressures where classical sprays transition to dense-fluid mixing with diminished surface tension. In this paper, such a model is presented to quantify this transition for liquid-oxygen–hydrogen and n-decane–gaseous-oxygen injection processes. The analysis reveals that respective molecular interfaces break down not necessarily because of vanishing surface tension forces but instead because of the combination of broadened interfaces and a reduction in mean free molecular path. When this occurs, the interfacial structure itself enters the continuum regime, where transport processes rather than intermolecular forces dominate. Using this model,more » regime diagrams for the respective systems are constructed that show the range of operating pressures and temperatures where this transition occurs. The analysis also reveals the conditions where classical spray dynamics persists even at high supercritical pressures. As a result, it demonstrates that, depending on the composition and temperature of the injected fluids, the injection process can exhibit either classical spray atomization, dense-fluid diffusion-dominated mixing, or supercritical mixing phenomena at chamber pressures encountered in state-of-the-art liquid rocket engines.« less

  17. Atomization and dense-fluid breakup regimes in liquid rocket engines

    SciTech Connect

    Oefelein, Joseph; Dahms, Rainer Norbert Uwe

    2015-04-20

    Until recently, modern theory has lacked a fundamentally based model to predict the operating pressures where classical sprays transition to dense-fluid mixing with diminished surface tension. In this paper, such a model is presented to quantify this transition for liquid-oxygen–hydrogen and n-decane–gaseous-oxygen injection processes. The analysis reveals that respective molecular interfaces break down not necessarily because of vanishing surface tension forces but instead because of the combination of broadened interfaces and a reduction in mean free molecular path. When this occurs, the interfacial structure itself enters the continuum regime, where transport processes rather than intermolecular forces dominate. Using this model, regime diagrams for the respective systems are constructed that show the range of operating pressures and temperatures where this transition occurs. The analysis also reveals the conditions where classical spray dynamics persists even at high supercritical pressures. As a result, it demonstrates that, depending on the composition and temperature of the injected fluids, the injection process can exhibit either classical spray atomization, dense-fluid diffusion-dominated mixing, or supercritical mixing phenomena at chamber pressures encountered in state-of-the-art liquid rocket engines.

  18. PREFACE: 1st International Conference on Mechanical Engineering Research 2011 (ICMER2011)

    NASA Astrophysics Data System (ADS)

    Abu Bakar, Rosli

    2012-09-01

    The year 2010 represented a significant milestone in the history of the Mechanical Engineering community with the organization of the first and second national level conferences (National Conference in Mechanical Engineering for Research, 1st and 2nd NCMER) at Universiti Malaysia Pahang on 26-27 May and 3-4 December 2010. The conferences attracted a large number of delegates from different premier academic and research institutions in the country to participate and share their research experiences at the conference. The International Conference on Mechanical Engineering Research (ICMER 2011) followed on from the first and second conferences due to good support from researchers. The ICMER 2011 is a good platform for researchers and postgraduate students to present their latest finding in research. The conference covers a wide range of topics including the internal combustion engine, machining processes, heat and mass transfer, fuel, biomechanical analysis, aerodynamic analysis, thermal comfort, computational techniques, design and simulation, automotive transmission, optimization techniques, hybrid electric vehicles, engine vibration, heat exchangers, finite element analysis, computational fluid dynamics, green energy, vehicle dynamics renewable energy, combustion, design, product development, advanced experimentation techniques, to name but a few. The international conference has helped to bridge the gap between researchers working at different institutions and in different countries to share their knowledge and has helped to motivate young scientists with their research. This has also given some clear direction for further research from the deliberations of the conference. Several people have contributed in different ways to the success of the conference. We thank the keynote speakers and all authors of the contributed papers, for the cooperation rendered to us in the publication of the CD conference proceedings. In particular, we would like to place on record our

  19. Quarterly Bulletin of the Division of Mechanical Engineering and the National Aeronautical Establishment.

    DTIC Science & Technology

    PHYSICS LABORATORIES, REPORTS), (*SCIENTIFIC RESEARCH, CANADA), ACOUSTICS, WIND TUNNEL MODELS, TURBULENCE, MECHANICAL ENGINEERING , TURBOJET ENGINES, BUILDINGS, GUST LOADS, NOISE, STRESS(PHYSIOLOGY), RADIOBIOLOGY, AIR POLLUTION

  20. The NASA Lewis Research Center Internal Fluid Mechanics Facility

    NASA Technical Reports Server (NTRS)

    Porro, A. R.; Hingst, W. R.; Wasserbauer, C. A.; Andrews, T. B.

    1991-01-01

    An experimental facility specifically designed to investigate internal fluid duct flows is described. It is built in a modular fashion so that a variety of internal flow test hardware can be installed in the facility with minimal facility reconfiguration. The facility and test hardware interfaces are discussed along with design constraints of future test hardware. The plenum flow conditioning approach is also detailed. Available instrumentation and data acquisition capabilities are discussed. The incoming flow quality was documented over the current facility operating range. The incoming flow produces well behaved turbulent boundary layers with a uniform core. For the calibration duct used, the boundary layers approached 10 percent of the duct radius. Freestream turbulence levels at the various operating conditions varied from 0.64 to 0.69 percent of the average freestream velocity.

  1. Personal Computer (PC) based image processing applied to fluid mechanics

    NASA Astrophysics Data System (ADS)

    Cho, Y.-C.; McLachlan, B. G.

    1987-10-01

    A PC based image processing system was employed to determine the instantaneous velocity field of a two-dimensional unsteady flow. The flow was visualized using a suspension of seeding particles in water, and a laser sheet for illumination. With a finite time exposure, the particle motion was captured on a photograph as a pattern of streaks. The streak pattern was digitized and processed using various imaging operations, including contrast manipulation, noise cleaning, filtering, statistical differencing, and thresholding. Information concerning the velocity was extracted from the enhanced image by measuring the length and orientation of the individual streaks. The fluid velocities deduced from the randomly distributed particle streaks were interpolated to obtain velocities at uniform grid points. For the interpolation a simple convolution technique with an adaptive Gaussian window was used. The results are compared with a numerical prediction by a Navier-Stokes computation.

  2. Personal Computer (PC) based image processing applied to fluid mechanics

    NASA Technical Reports Server (NTRS)

    Cho, Y.-C.; Mclachlan, B. G.

    1987-01-01

    A PC based image processing system was employed to determine the instantaneous velocity field of a two-dimensional unsteady flow. The flow was visualized using a suspension of seeding particles in water, and a laser sheet for illumination. With a finite time exposure, the particle motion was captured on a photograph as a pattern of streaks. The streak pattern was digitized and processed using various imaging operations, including contrast manipulation, noise cleaning, filtering, statistical differencing, and thresholding. Information concerning the velocity was extracted from the enhanced image by measuring the length and orientation of the individual streaks. The fluid velocities deduced from the randomly distributed particle streaks were interpolated to obtain velocities at uniform grid points. For the interpolation a simple convolution technique with an adaptive Gaussian window was used. The results are compared with a numerical prediction by a Navier-Stokes computation.

  3. The Influence of Fluid Overload on the Length of Mechanical Ventilation in Pediatric Congenital Heart Surgery.

    PubMed

    Sampaio, Tatiana Z A L; O'Hearn, Katie; Reddy, Deepti; Menon, Kusum

    2015-12-01

    Fluid overload and prolonged mechanical ventilation lead to worse outcomes in critically ill children. However, the association between these variables in children following congenital heart surgery is unknown. The objectives of this study were to describe the association between fluid overload and duration of mechanical ventilation, oxygen requirement and radiologic findings of pulmonary and chest wall edema. This study is a retrospective chart review of patients who underwent congenital heart surgery between June 2010 and December 2013. Univariate and multivariate associations between maximum cumulative fluid balance and length of mechanical ventilation and OI were tested using the Spearman correlation test and multiple linear regression models, respectively. There were 85 eligible patients. Maximum cumulative fluid balance was associated with duration of mechanical ventilation (adjusted analysis beta coefficient = 0.53, CI 0.38-0.66, P < 0.001), length of stay in the pediatric intensive care unit (Spearman's correlation = 0.45, P < 0.001), and presence of chest wall edema and pleural effusions on chest radiograph (Mann-Whitney test, P = 0.003). Amount of red blood cells transfused and use of nitric oxide were independently associated with increased duration of mechanical ventilation (P = 0.012 and 0.014, respectively). Fluid overload is associated with prolonged duration of mechanical ventilation and PICU length of stay after congenital heart surgery. Fluid overload was also associated with physiological markers of respiratory restriction. A randomized controlled trial of a restrictive versus liberal fluid replacement strategy is necessary in this patient population, but in the meantime, accumulating observational evidence suggests that cautious use of fluid in the postoperative care may be warranted.

  4. Mechanics of interstitial-lymphatic fluid transport: theoretical foundation and experimental validation.

    PubMed

    Swartz, M A; Kaipainen, A; Netti, P A; Brekken, C; Boucher, Y; Grodzinsky, A J; Jain, R K

    1999-12-01

    Interstitial fluid movement is intrinsically linked to lymphatic drainage. However, their relationship is poorly understood, and associated pathologies are mostly untreatable. In this work we test the hypothesis that bulk tissue fluid movement can be evaluated in situ and described by a linear biphasic theory which integrates the regulatory function of the lymphatics with the mechanical stresses of the tissue. To accomplish this, we develop a novel experimental and theoretical model using the skin of the mouse tail. We then use the model to demonstrate how interstitial-lymphatic fluid movement depends on a balance between the elasticity, hydraulic conductivity, and lymphatic conductance as well as to demonstrate how chronic swelling (edema) alters the equipoise between tissue fluid balance parameters. Specifically, tissue fluid equilibrium is perturbed with a continuous interstitial infusion of saline into the tip of the tail. The resulting gradients in tissue stress are measured in terms of interstitial fluid pressure using a servo-null system. These measurements are then fit to the theory to provide in vivo estimates of the tissue hydraulic conductivity, elastic modulus, and overall resistance to lymphatic drainage. Additional experiments are performed on edematous tails to show that although chronic swelling causes an increase in the hydraulic conductivity, its greatly increased distensibility (due to matrix remodeling) dampens the driving forces for fluid movement and leads to fluid stagnation. This model is useful for examining potential treatments for edema and lymphatic disorders as well as substances which may alter tissue fluid balance and/or lymphatic drainage.

  5. Innovative Mechanical Engineering Technologies, Equipment and Materials-2013

    NASA Astrophysics Data System (ADS)

    Ilnaz Izailovich, Fayrushin; Nail Faikovich, Kashapov; Mahmut Mashutovich, Ganiev

    2014-12-01

    In the period from 25 to 27 September 2013 the city of Kazan hosted the International Scientific Conference "Innovative mechanical engineering technologies, equipment and materials - 2013" (IRTC "IMETEM - 2013"). The conference was held on the grounds of "Kazanskaya Yarmarka" (Kazan). The conference plenary meeting was held with the participation of the Republic of Tatarstan, breakout sessions, forum "Improving the competitiveness and efficiency of engineering enterprises in the WTO" and a number of round tables. Traditionally, the event was followed by the 13th International specialized exhibition "Engineering. Metalworking. Kazan ", in which were presented the development of innovative enterprises in the interests of the Russian Federation of Industry of Republic of Tatarstan, to support the "Foundation for Assistance to Small Innovative Enterprises in Science and Technology" and the 8th specialized exhibition "TechnoWelding". Kashapov Nail, D.Sc., professor (Kazan Federal University)

  6. Interactive training model of TRIZ for mechanical engineers in China

    NASA Astrophysics Data System (ADS)

    Tan, Runhua; Zhang, Huangao

    2014-03-01

    Innovation is a process of taking an original idea and converting it into a business value, in which the engineers face some inventive problems which can be solved hardly by experience. TRIZ, as a new theory for companies in China, provides both conceptual and procedural knowledge for finding and solving inventive problems. Because the government plays a leading role in the diffusion of TRIZ, too many companies from different industries are waiting to be trained, but the quantity of the trainers mastering TRIZ is incompatible with that requirement. In this context, to improve the training effect, an interactive training model of TRIZ for the mechanical engineers in China is developed and the implementation in the form of training classes is carried out. The training process is divided into 6 phases as follows: selecting engineers, training stage-1, finding problems, training stage-2, finding solutions and summing up. The government, TRIZ institutions and companies to join the programs interact during the process. The government initiates and monitors a project in form of a training class of TRIZ and selects companies to join the programs. Each selected companies choose a few engineers to join the class and supervises the training result. The TRIZ institutions design the training courses and carry out training curriculum. With the beginning of the class, an effective communication channel is established by means of interview, discussion face to face, E-mail, QQ and so on. After two years training practices, the results show that innovative abilities of the engineers to join and pass the final examinations increased distinctly, and most of companies joined the training class have taken congnizance of the power of TRIZ for product innovation. This research proposes an interactive training model of TRIZ for mechanical engineers in China to expedite the knowledge diffusion of TRIZ.

  7. Formula student as part of a mechanical engineering curriculum

    NASA Astrophysics Data System (ADS)

    Davies, Huw Charles

    2013-10-01

    Formula Student (FS) is a multi-university student design competition managed by the UK Institution of Mechanical Engineers. Students are required to demonstrate and prove their creativity and engineering skills through the design, manufacture and financing of a small formula style race car. This paper seeks to explore the educational value that derives from the FS activity through a series of semi-structured interviews with key stakeholders. Through the analysis of the interview data, it was found that the FS activity supported development of student skills and competencies in the following areas: use of engineering knowledge to support the application of existing and emerging technology; application of theoretical and practical knowledge to the solution of engineering problems; development of technical and commercial management skills; development of effective interpersonal skills, including communication skills; and demonstration of personal commitment to professional development. In addition, a number of areas for implementing 'good practise' have been identified. The information herein supports educators in their responsibility to help meet the needs of the engineering industry for high quality graduates.

  8. Applied environmental fluid mechanics: what's the weather in your backyard?

    NASA Astrophysics Data System (ADS)

    Chow, F. K.

    2011-12-01

    The microclimates of the San Francisco Bay Area can lead to 30-40F differences in temperature from the coast to just 30 miles inland. The reasons for this include local topography which affects development of the atmospheric boundary layer. A Bay Area resident's experience of fog, air pollution, and weather events therefore differs greatly depending on exactly where they live. Such local weather phenomena provide a natural topic for introduction to boundary layer processes and are the basis of a new course developed at the University of California, Berkeley. This course complements the PI's research focus on numerical methods applied to atmospheric boundary layer flow over complex terrain. This new outreach and research-based course was created to teach students about the boundary layer and teach them how to use a community weather prediction model, WRF, to simulate conditions in the local area, while at the same time being actively involved in public outreach. The course was offered in the Civil and Environmental Engineering department with the collaboration and support of the Lawrence Hall of Science, Berkeley's public science museum. The students chose topics such as air quality, wind energy, climate change, and plume dispersion, all applied to the local San Francisco Bay Area. The students conducted independent research on their team projects, involving literature reviews, numerical model setup, and analysis of model results through comparison with field observations. The outreach component of the course included website design and culminated in demonstrations at the Lawrence Hall of Science. The seven student teams presented hands-on demos to 300-400 visitors, mostly kids 4-9 years old and their parents. Involving students directly in outreach efforts is hoped to encourage continued integration of research and education in their own careers. Early exposure to numerical modeling also improves student technical skills for future career experiences . Given

  9. Analysis of the Lifecycle of Mechanical Engineering Products

    NASA Astrophysics Data System (ADS)

    Gubaydulina, R. H.; Gruby, S. V.; Davlatov, G. D.

    2016-08-01

    Principal phases of the lifecycle of mechanical engineering products are analyzed in the paper. The authors have developed methods and procedures to improve designing, manufacturing, operating and recycling of the machine. It has been revealed that economic lifecycle of the product is a base for appropriate organization of mechanical engineering production. This lifecycle is calculated as a minimal sum total of consumer and producer costs. The machine construction and its manufacturing technology are interrelated through a maximal possible company profit. The products are to be recycled by their producer. Recycling should be considered as a feedback phase, necessary to make the whole lifecycle of the product a constantly functioning self-organizing system. The principles, outlined in this paper can be used as fundamentals to develop an automated PLM-system.

  10. Mechanics of fluid flow over compliant wrinkled polymeric surfaces

    NASA Astrophysics Data System (ADS)

    Raayai, Shabnam; McKinley, Gareth; Boyce, Mary

    2014-03-01

    Skin friction coefficients (based on frontal area) of sharks and dolphins are lower than birds, fish and swimming beetles. By either exploiting flow-induced changes in their flexible skin or microscale textures, dolphins and sharks can change the structure of the fluid flow around them and thus reduce viscous drag forces on their bodies. Inspired by this ability, investigators have tried using compliant walls and riblet-like textures as drag reduction methods in aircraft and marine industries and have been able to achieve reductions up to 19%. Here we investigate flow-structure interaction and wrinkling of soft polymer surfaces that can emulate shark riblets and dolphin's flexible skin. Wrinkling arises spontaneously as the result of mismatched deformation of a thin stiff coating bound to a thick soft elastic substrate. Wrinkles can be fabricated by controlling the ratio of the stiffness of the coating and substrate, the applied displacement and the thickness of the coating. In this work we will examine the evolution in the kinematic structures associated with steady viscous flow over the polymer wrinkled surfaces and in particular compare the skin friction with corresponding results for flow over non-textured and rigid surfaces.

  11. Fluid Mechanics Produces Conflicting Constraints During Olfactory Navigation

    NASA Astrophysics Data System (ADS)

    Webster, D. R.; Weissburg, M. J.

    2002-11-01

    Blue crabs foraging in turbulent odor plumes must acquire useful chemical cues in addition to responding to fluid forces imposed on their body. The drag force experienced by blue crabs is shown to be a function of the body orientation angle relative to the flow (maximum at 0 deg and minimum at 90 degrees). Crabs turn their body to an orientation (near 90 deg) that minimizes the drag force in high-speed flows with and without odor present in order to lower the cost of locomotion. At lower flow speeds they turn to a higher drag orientation (near 50 deg) only in the presence of odor. At a smaller relative orientation angle to the flow, the antennules receive more direct contact with the advected odor filaments, which mediate upstream movement, and the appendage chemosensors are separated in the cross-stream direction, which facilitates a useful bilateral comparison. Thus, blue crabs appear to accept a higher drag force (and cost of locomotion) in order to place their antennules and appendages in positions to collect useful chemosensory information. They do so only at low flow speeds, which suggests that they weigh the potential benefits to the costs.

  12. Crystal growth and fluid mechanics problems in directional solidification

    NASA Technical Reports Server (NTRS)

    Tanveer, Saleh; Baker, Gregory R.; Foster, Michael R.

    1994-01-01

    Broadly speaking, our efforts have been concentrated in two aspects of directional solidification: (A) a more complete theoretical understanding of convection effects in a Bridgman apparatus; and (B) a clear understanding of scalings of various features of dendritic crystal growth in the sensitive limit of small capillary effects. For studies that fall within class A, the principal objectives are as follows: (A1) Derive analytical formulas for segregation, interfacial shape and fluid velocities in mathematically amenable asymptotic limits. (A2) Numerically verify and extend asymptotic results to other ranges of parameter space with a view to a broader physical understanding of the general trends. With respect to studies that fall within class B, the principal objectives include answering the following questions about dendritic crystal growth: (B1) Are there unsteady dendrite solutions in 2-D to the completely nonlinear time evolving equations in the small surface tension limit with only a locally steady tip region with well defined tip radius and velocity? Is anisotropy in surface tension necessary for the existence of such solutions as it is for a true steady state needle crystal? How does the size of such a local region depend on capillary effects, anisotropy and undercooling? (B2) How do the different control parameters affect the nonlinear amplification of tip noise and dendritic side branch coarsening?

  13. Patterns for Fluid Management: The Mechanical Origins of Microarchitectures

    NASA Astrophysics Data System (ADS)

    Radja, Asja; Lavrentovich, Maxim; Horsley, Eric; Kamien, Randall; Sweeney, Alison

    Pollen grains are the vehicles for the male germ line in land plants and are famous for the intricate microarchitectures of their protective coverings. It is not known whether these sub-micron-scale patterns have a functional role. A given microarchitectural pattern is maintained over geological time within a single species, yet, despite similar mechanisms of pollen development in all species, different species have extremely variable patterns. Until recently, many proposed mechanisms of pollen pattern formation were attributed to top-down assembly processes directed by the pollen cytoskeleton. We propose a novel view in which bottom-up mechanical processes akin to thermodynamic phase transitions may cause the final pollen structure. Here, we present a temporal view of pattern formation using several microscopy techniques. Our data show a rapid appearance of surface microstructures. We test the hypothesis of bottom-up pattern formation by physically manipulating the pattern formation process with mechanical forces and chemical solvents. Our data are consistent with bottom-up formation of these patterns; we discuss a hypothesis of pattern formation in this system involving Brazovskii phase transitions templated on a spherical geometry.

  14. Ongoing Analyses of Rocket Based Combined Cycle Engines by the Applied Fluid Dynamics Analysis Group at Marshall Space Flight Center

    NASA Technical Reports Server (NTRS)

    Ruf, Joseph H.; Holt, James B.; Canabal, Francisco

    2001-01-01

    This paper presents the status of analyses on three Rocket Based Combined Cycle (RBCC) configurations underway in the Applied Fluid Dynamics Analysis Group (TD64). TD64 is performing computational fluid dynamics (CFD) analysis on a Penn State RBCC test rig, the proposed Draco axisymmetric RBCC engine and the Trailblazer engine. The intent of the analysis on the Penn State test rig is to benchmark the Finite Difference Navier Stokes (FDNS) code for ejector mode fluid dynamics. The Draco analysis was a trade study to determine the ejector mode performance as a function of three engine design variables. The Trailblazer analysis is to evaluate the nozzle performance in scramjet mode. Results to date of each analysis are presented.

  15. Mechanics of layered anisotropic poroelastic media with applications to effective stress for fluid permeability

    SciTech Connect

    Berryman, J.G.

    2010-06-01

    The mechanics of vertically layered porous media has some similarities to and some differences from the more typical layered analysis for purely elastic media. Assuming welded solid contact at the solid-solid interfaces implies the usual continuity conditions, which are continuity of the vertical (layering direction) stress components and the horizontal strain components. These conditions are valid for both elastic and poroelastic media. Differences arise through the conditions for the pore pressure and the increment of fluid content in the context of fluid-saturated porous media. The two distinct conditions most often considered between any pair of contiguous layers are: (1) an undrained fluid condition at the interface, meaning that the increment of fluid content is zero (i.e., {delta}{zeta} = 0), or (2) fluid pressure continuity at the interface, implying that the change in fluid pressure is zero across the interface (i.e., {delta}p{sub f} = 0). Depending on the types of measurements being made on the system and the pertinent boundary conditions for these measurements, either (or neither) of these two conditions might be directly pertinent. But these conditions are sufficient nevertheless to be used as thought experiments to determine the expected values of all the poroelastic coefficients. For quasi-static mechanical changes over long time periods, we expect drained conditions to hold, so the pressure must then be continuous. For high frequency wave propagation, the pore-fluid typically acts as if it were undrained (or very nearly so), with vanishing of the fluid increment at the boundaries being appropriate. Poroelastic analysis of both these end-member cases is discussed, and the general equations for a variety of applications to heterogeneous porous media are developed. In particular, effective stress for the fluid permeability of such poroelastic systems is considered; fluid permeabilities characteristic of granular media or tubular pore shapes are treated

  16. Finite element procedures for coupled linear analysis of heat transfer, fluid and solid mechanics

    NASA Technical Reports Server (NTRS)

    Sutjahjo, Edhi; Chamis, Christos C.

    1993-01-01

    Coupled finite element formulations for fluid mechanics, heat transfer, and solid mechanics are derived from the conservation laws for energy, mass, and momentum. To model the physics of interactions among the participating disciplines, the linearized equations are coupled by combining domain and boundary coupling procedures. Iterative numerical solution strategy is presented to solve the equations, with the partitioning of temporal discretization implemented.

  17. Mechanical instability induced by water weakening in laboratory fluid injection tests

    NASA Astrophysics Data System (ADS)

    David, C.; Dautriat, J.; Sarout, J.; Delle Piane, C.; Menéndez, B.; Macault, R.; Bertauld, D.

    2015-06-01

    To assess water-weakening effects in reservoir rocks, previous experimental studies have focused on changes in the failure envelopes derived from mechanical tests conducted on rocks fully saturated either with water or with inert fluids. So far, little attention has been paid to the mechanical behavior during fluid injection under conditions similar to enhanced oil recovery operations. We studied the effect of fluid injection on the mechanical behavior of the weakly consolidated Sherwood sandstone in laboratory experiments. Our specimens were instrumented with 16 ultrasonic P wave transducers for both passive and active acoustic monitoring during loading and fluid injection to record the acoustic signature of fluid migration in the pore space and the development of damage. Calibration triaxial tests were conducted on three samples saturated with air, water, or oil. In a second series of experiments, water and inert oil were injected into samples critically loaded up to 80% or 70% of the dry or oil-saturated compressive strength, respectively, to assess the impact of fluid migration on mechanical strength and elastic properties. The fluids were injected with a low back pressure to minimize effective stress variations during injection. Our observations show that creep takes place with a much higher strain rate for water injection compared to oil injection. The most remarkable difference is that water injection in both dry and oil-saturated samples triggers mechanical instability (macroscopic failure) within half an hour whereas oil injection does not after several hours. The analysis of X-ray computed tomography images of postmortem samples revealed that the mechanical instability was probably linked to loss of cohesion in the water-invaded region.

  18. Modeling Potential Carbon Monoxide Exposure Due to Operation of a Major Rocket Engine Altitude Test Facility Using Computational Fluid Dynamics

    NASA Technical Reports Server (NTRS)

    Blotzer, Michael J.; Woods, Jody L.

    2009-01-01

    This viewgraph presentation reviews computational fluid dynamics as a tool for modelling the dispersion of carbon monoxide at the Stennis Space Center's A3 Test Stand. The contents include: 1) Constellation Program; 2) Constellation Launch Vehicles; 3) J2X Engine; 4) A-3 Test Stand; 5) Chemical Steam Generators; 6) Emission Estimates; 7) Located in Existing Test Complex; 8) Computational Fluid Dynamics; 9) Computational Tools; 10) CO Modeling; 11) CO Model results; and 12) Next steps.

  19. Channelled scaffolds for engineering myocardium with mechanical stimulation.

    PubMed

    Zhang, Ting; Wan, Leo Q; Xiong, Zhuo; Marsano, Anna; Maidhof, Robert; Park, Miri; Yan, Yongnian; Vunjak-Novakovic, Gordana

    2012-10-01

    The characteristics of the matrix (composition, structure, mechanical properties) and external culture environment (pulsatile perfusion, physical stimulation) of the heart are important characteristics in the engineering of functional myocardial tissue. This study reports on the development of chitosan-collagen scaffolds with micropores and an array of parallel channels (~ 200 µm in diameter) that were specifically designed for cardiac tissue engineering using mechanical stimulation. The scaffolds were designed to have similar structural and mechanical properties of those of native heart matrix. Scaffolds were seeded with neonatal rat heart cells and subjected to dynamic tensile stretch using a custom designed bioreactor. The channels enhanced oxygen transport and facilitated the establishment of cell connections within the construct. The myocardial patches (14 mm in diameter, 1-2 mm thick) consisted of metabolically active cells that began to contract synchronously after 3 days of culture. Mechanical stimulation with high tensile stress promoted cell alignment, elongation, and expression of connexin-43 (Cx-43). This study confirms the importance of scaffold design and mechanical stimulation for the formation of contractile cardiac constructs.

  20. Channeled Scaffolds for Engineering Myocardium with Mechanical Stimulation

    PubMed Central

    Zhang, Ting; Wan, Leo Q.; Xiong, Zhuo; Marsano, Anna; Maidhof, Robert; Park, Miri; Yan, Yongnian; Vunjak-Novakovic, Gordana

    2011-01-01

    The characteristics of the matrix (composition, structure, mechanical properties) and external culture environment (pulsatile perfusion, physical stimulation) are critically important for engineering functional myocardial tissue. We report the development of chitosan-collagen scaffolds with micro-pores and an array of parallel channels (~200 μm in diameter) that were specifically designed for cardiac tissue engineering with mechanical stimulation. The scaffolds were designed to have the structural and mechanical properties similar to those of the native human heart matrix. Scaffolds were seeded with neonatal rat heart cells and subjected to dynamic tensile stretch using a custom-designed bioreactor. The channels enhanced oxygen transport and facilitated the establishment of cell connections within the construct. The myocardial patches (14 mm in diameter, 1–2 mm thick) consisted of metabolically active cells and started to contract synchronously after 3 days of culture. Mechanical stimulation with high tensile stresses promoted cell alignment, elongation, and the expression of connexin-43 (Cx-43). This study confirms the importance of scaffold design and mechanical stimulation for the formation of contractile cardiac constructs. PMID:22081518

  1. Fluid flow structure around the mixer in a reactor with mechanical mixing

    SciTech Connect

    Lecheva, A.; Zheleva, I.

    2015-10-28

    Fluid flow structure around the mixer in a cylindrical reactor with mechanical mixing is studied and numerical results are presented in this article. The model area is complex because of the presence of convex corners of the mixer in the fluid flow. Proper boundary conditions for the vorticity calculated on the base of the stream function values near solid boundaries of the examined area are presented. The boundary value problem of motion of swirling incompressible viscous fluid in a vertical tank reactor with a mixer is solved numerically. The calculations are made by a computer code, written in MATLAB. The complex structure of the flow around the mixing disk is described and commented.

  2. Stress Fracture Etiology as Dependent on Mechanically Induced Fluid Flow

    DTIC Science & Technology

    2004-08-01

    Martin, M . B. Schaffler, and C. H . Turner. Bone microdamage and skeletal fragility in osteoporotic and stress fractures. J.Bone Miner.Res. 12:6...ulnae (Adams et al., 1995). Endosteal and periosteal were labeled weekly using tetracycline solution (15 ing- new bone formation, as well as...Transport mechanism operating Huiskes, R.. Weinans, H ., Grootenboer, H.J., Dalstra, M ., Fudala. B., between blood supply and osteocytes in long bones

  3. Constraints from fluid inclusions on sulfide precipitation mechanisms and ore fluid migration in the Viburnum Trend lead district, Missouri

    USGS Publications Warehouse

    Rowan, E.L.; Leach, D.L.

    1989-01-01

    Homogenization temperatures and freezing point depressions were determined for fluid inclusions in Bonneterre Dolomite-hosted dolomite cements in mine samples, as well as drill core from up to 13 km outside of the district. A well-defined cathodoluminescent zonation distinguishes dolomite growth zones as older or younger than main-stage mineralization. Homogenization temperatures and salinities in samples from mines are not systematically different from those of samples outside of the district. The absence of a significant, recognizable decrease in temperature either vertically within the section or east-west across the district, coupled with the minor amount of silica in the district, argues against cooling as a primary cause of sulfide precipitation. In a reduced sulfur mineralization model with Pb carried as chloride complexes, dilution is also a possible sulfide precipitation mechanism. The difference in Pb solubility in the extremes of the chloride concentration range, 3.9 vs. 5.9 molal, reaches 1 ppm only for pH values below approximately 4.5. The distribution of warm inclusions beyond the Viburnum Trend district implies that fluid migration was regional in scale. Elevated temperatures observed in fluid inclusions at shallow stratigraphic depths are consistent with a gravity flow hydrologic system characterized by rapid flow rates and the capacity for advective heat transport. -from Authors

  4. Computational fluid dynamics modeling of momentum transport in rotating wall perfused bioreactor for cartilage tissue engineering.

    PubMed

    Cinbiz, Mahmut N; Tığli, R Seda; Beşkardeş, Işil Gerçek; Gümüşderelioğlu, Menemşe; Colak, Uner

    2010-11-01

    In this study, computational fluid dynamics (CFD) analysis of a rotating-wall perfused-vessel (RWPV) bioreactor is performed to characterize the complex hydrodynamic environment for the simulation of cartilage development in RWPV bioreactor in the presence of tissue-engineered cartilage constructs, i.e., cell-chitosan scaffolds. Shear stress exerted on chitosan scaffolds in bioreactor was calculated for different rotational velocities in the range of 33-38 rpm. According to the calculations, the lateral and lower surfaces were exposed to 0.07926-0.11069 dyne/cm(2) and 0.05974-0.08345 dyne/cm(2), respectively, while upper surfaces of constructs were exposed to 0.09196-0.12847 dyne/cm(2). Results validate adequate hydrodynamic environment for scaffolds in RWPV bioreactor for cartilage tissue development which concludes the suitability of operational conditions of RWPV bioreactor.

  5. Validation of Computational Fluid Dynamic analysis of a rocket engine turbopump impeller

    NASA Astrophysics Data System (ADS)

    Prueger, George H.; Lin, S. J.; Chan, Daniel C.; Eastland, Anthony H.

    1993-06-01

    Incorporation of Computational Fluid Dynamic analysis into the design process of turbomachinery components requires extensive validation of the analysis tools. This validation must include not only investigation of the capabilities of the CFD tool to adequately predict the flow structures present, but also the level of geometric modeling and grid sizes required. Validation of Rocketdyne's Three-Dimensional Elliptic Analysis Code for Turbomachinery, REACT3D, was accomplished by comparison to test data obtained with the Space Shuttle Main Engine High Pressure Fuel Pump impeller. Comparisons were made for averaged quantities which are commonly used in the design process as well as for the detail jet-wake features of the impeller discharge flow. The validation shows that with current computer technology it is feasible to use CFD analysis within the limits of design schedules and budgets.

  6. The fluid mechanics of continuous flow electrophoresis in perspective

    NASA Technical Reports Server (NTRS)

    Saville, D. A.

    1980-01-01

    Buoyancy alters the flow in continuous flow electrophoresis chambers through the mechanism of hydrodynamic instability and, when the instability is supressed by careful cooling of the chamber boundaries, by restructuring the axial flow. The expanded roles of buoyancy follow upon adapting the size of the chamber and the electric field so as to fractionate certain sorts of cell populations. Scale-up problems, hydrodynamic stability and the altered flow fields are discussed to show how phenomena overlooked in the design and operations of narrow-gap devices take on an overwhelming importance in wide-gap chambers

  7. 46 CFR 113.35-9 - Mechanical engine order telegraph systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Mechanical engine order telegraph systems. 113.35-9 Section 113.35-9 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-9 Mechanical engine...

  8. 46 CFR 113.35-9 - Mechanical engine order telegraph systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Mechanical engine order telegraph systems. 113.35-9 Section 113.35-9 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-9 Mechanical engine...

  9. 46 CFR 113.35-13 - Mechanical engine order telegraph systems; operation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Mechanical engine order telegraph systems; operation...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-13 Mechanical engine order telegraph systems; operation. If more than one transmitter operates...

  10. 46 CFR 113.35-13 - Mechanical engine order telegraph systems; operation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Mechanical engine order telegraph systems; operation...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-13 Mechanical engine order telegraph systems; operation. If more than one transmitter operates...

  11. 46 CFR 113.35-9 - Mechanical engine order telegraph systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Mechanical engine order telegraph systems. 113.35-9 Section 113.35-9 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-9 Mechanical engine...

  12. 46 CFR 113.35-9 - Mechanical engine order telegraph systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Mechanical engine order telegraph systems. 113.35-9 Section 113.35-9 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-9 Mechanical engine...

  13. 46 CFR 113.35-13 - Mechanical engine order telegraph systems; operation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Mechanical engine order telegraph systems; operation...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-13 Mechanical engine order telegraph systems; operation. If more than one transmitter operates...

  14. 46 CFR 113.35-13 - Mechanical engine order telegraph systems; operation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Mechanical engine order telegraph systems; operation...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-13 Mechanical engine order telegraph systems; operation. If more than one transmitter operates...

  15. 46 CFR 113.35-9 - Mechanical engine order telegraph systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Mechanical engine order telegraph systems. 113.35-9 Section 113.35-9 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-9 Mechanical engine...

  16. 46 CFR 113.35-13 - Mechanical engine order telegraph systems; operation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Mechanical engine order telegraph systems; operation...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-13 Mechanical engine order telegraph systems; operation. If more than one transmitter operates...

  17. Mechanical stimulation improves tissue-engineered human skeletal muscle.

    PubMed

    Powell, Courtney A; Smiley, Beth L; Mills, John; Vandenburgh, Herman H

    2002-11-01

    Human bioartificial muscles (HBAMs) are tissue engineered by suspending muscle cells in collagen/MATRIGEL, casting in a silicone mold containing end attachment sites, and allowing the cells to differentiate for 8 to 16 days. The resulting HBAMs are representative of skeletal muscle in that they contain parallel arrays of postmitotic myofibers; however, they differ in many other morphological characteristics. To engineer improved HBAMs, i.e., more in vivo-like, we developed Mechanical Cell Stimulator (MCS) hardware to apply in vivo-like forces directly to the engineered tissue. A sensitive force transducer attached to the HBAM measured real-time, internally generated, as well as externally applied, forces. The muscle cells generated increasing internal forces during formation which were inhibitable with a cytoskeleton depolymerizer. Repetitive stretch/relaxation for 8 days increased the HBAM elasticity two- to threefold, mean myofiber diameter 12%, and myofiber area percent 40%. This system allows engineering of improved skeletal muscle analogs as well as a nondestructive method to determine passive force and viscoelastic properties of the resulting tissue.

  18. Mechanical stimulation improves tissue-engineered human skeletal muscle

    NASA Technical Reports Server (NTRS)

    Powell, Courtney A.; Smiley, Beth L.; Mills, John; Vandenburgh, Herman H.

    2002-01-01

    Human bioartificial muscles (HBAMs) are tissue engineered by suspending muscle cells in collagen/MATRIGEL, casting in a silicone mold containing end attachment sites, and allowing the cells to differentiate for 8 to 16 days. The resulting HBAMs are representative of skeletal muscle in that they contain parallel arrays of postmitotic myofibers; however, they differ in many other morphological characteristics. To engineer improved HBAMs, i.e., more in vivo-like, we developed Mechanical Cell Stimulator (MCS) hardware to apply in vivo-like forces directly to the engineered tissue. A sensitive force transducer attached to the HBAM measured real-time, internally generated, as well as externally applied, forces. The muscle cells generated increasing internal forces during formation which were inhibitable with a cytoskeleton depolymerizer. Repetitive stretch/relaxation for 8 days increased the HBAM elasticity two- to threefold, mean myofiber diameter 12%, and myofiber area percent 40%. This system allows engineering of improved skeletal muscle analogs as well as a nondestructive method to determine passive force and viscoelastic properties of the resulting tissue.

  19. Magnetorheological fluid template for basic studies of mechanical-chemical effects during polishing

    NASA Astrophysics Data System (ADS)

    Miao, Chunlin; Bristol, Kirk M.; Marino, Anne E.; Shafrir, Shai N.; DeGroote, Jessica E.; Jacobs, Stephen D.

    2007-09-01

    We developed a new magnetorheological (MR) fluid for studying the relative contributions of mechanics and chemistry in polishing hard materials. The base carrier fluid is a mixture of two non-aqueous liquids. At conventional carbonyl iron (CI) magnetic particle concentrations, removal rates with this formulation were unacceptably low for the polycrystalline optical ceramic aluminum oxynitride (ALON). We overcame this problem by creating a high magnetic solids concentration suspension consisting of a blend of large and small CI particles. Our test bed for experiments was a magnetorheological finishing (MRF) spot-taking machine (STM) that can only polish spots into a non-rotating part. We demonstrated that, using this new MR fluid formulation, we could substantially increase peak removal rates on ALON with small additions of nonmagnetic, nanodiamond abrasives. Material removal with this fluid was assumed to be predominately driven by mechanics. With the addition of small amounts of DI water to the base fluid containing nanodiamonds, the peak removal rate showed an additional increase, presumably due to the altered fluid rheology and possibly chemical interactions. It is possible, however, that this result is due to increased fluid viscosity as well. Interestingly, the microtexture on the surfaces of the ALON grains (albeit-two different ALON parts) showed distinctly different features when spotted with nanodiamonds or with nanodiamonds and water, and an understanding of this phenomenon is the goal of future work. In this paper we describe the difficult fluid viscosity issues that were addressed in creating a viable, high removal rate, non-aqueous MR fluid template that could be pumped in the STM for several days of experiments.

  20. Monitoring fluid evolution in an Engineered Barrier System using NEO-magnets

    NASA Astrophysics Data System (ADS)

    Rigonat, N.; Butler, I. B.

    2015-12-01

    Long-term monitoring of the evolution of the engineered barrier system (EBS) of a Geological Disposal Facility (GDF) is important for establishing the safety case for deep disposal of the UK inventory of high level radioactive waste. With a view to developing techniques for remote fluid monitoring using magnetic properties, we have examined the correlation between the corrosion properties of NEO-magnets and related changes in the magnetic properties of the alloy with fluid chemistry and crystal-chemical changes of the Na-bentonite matrix. Batch experiments comprised fragments of NEO-magnets with deionised water, saline and alkaline solution both in the presence and absence of MX-80 bentonite, and were performed in sealed vessels for durations of up to 5 months at 70°C. This study combined PXRD, thermomagnetic and hysteresis analysis to demonstrate how progressive hydrogenation of the main magnetic phase led to a maximum loss of remanence and coercitivity and increasing Curie temperature in the samples reacted with deionised water with the samples reacted in saline and alkaline solutions showing smaller changes. Semi-quantitative analysis allowed comparison of the Curie temperatures with crystal-chemical parameters. This reveals a clear positive correlation of increasing lattice parameters a and c (and cell volume) with mean hydrogens per unit formula and the Curie temperature of the product NdFeB hydrides. Precipitation of Nd and Fe hydrides/oxyhydroxides is also demonstated by the PXRD data. A crucial role is played by the transformations occurring to the smectite matrix, in particular by the cation exchange in the interlayer, which causes precipitation of highly charged K- and Ca-smectites. This study demonstrates how NEO-magnets are capable of detecting water saturation in the EBS, and that the NdFeB corrosion properties are strongly controlled by the initial fluid composition and presence / absence of the bentonite matrix.

  1. Smart multifunctional fluids for lithium ion batteries: enhanced rate performance and intrinsic mechanical protection.

    PubMed

    Ding, Jie; Tian, Tongfei; Meng, Qing; Guo, Zaiping; Li, Weihua; Zhang, Peng; Ciacchi, Fabio T; Huang, Jewel; Yang, Wenrong

    2013-01-01

    Lithium ion batteries are attractive power sources for the consumer electronics market and are being aggressively developed for road transportation. Nevertheless, issues with safety and reliability need to be solved prior to the large-scale uptake of these batteries. There have recently been significant development and assessment of materials with resistance to mechanical abuse, with the aims of reinforcing the battery and preventing puncturing during a crash. Most of the work on battery mechanical safety has concentrated on the external packaging of batteries, with little attention being paid to the enclosed electrolyte. We report on smart multifunctional fluids that act as both highly conductive electrolytes and intrinsic mechanical protectors for lithium ion batteries. These fluids exhibit a shear thickening effect under pressure or impact and thus demonstrate excellent resistance to crushing. Also, the fluids show higher ionic conductivities and comparable redox stability windows to the commercial liquid electrolytes.

  2. Topological selection mechanism for conservation laws in incompressible stratified Euler fluids

    NASA Astrophysics Data System (ADS)

    Ortenzi, Giovanni; Chen, Shengqian; Camassa, Roberto; Falqui, Gregorio; Pedroni, Marco

    2014-11-01

    With his Kaffeeloeffel thought (``gedanken'') experiment, in 1910 Klein suggested that a topological change of an ideal fluid's domain can provide a mechanism for breaking the conservation of circulation enforced by Kelvin's Theorem. In our study, we extend this idea to more general conservation laws and explore the role of topological properties in the dynamics of an incompressible Euler fluid with stratification. In particular, we show that topologically non-trivial configurations of stratified fluid domains generate selection mechanisms for conserved quantities other than vorticity. In the talk we concentrate on the simple example of an air-water system in a channel, which encapsulates all the main points of these selection mechanisms. Among other examples, we show that the connection properties of the air domain affect total horizontal momentum conservation, despite the translational invariance of the system and its consequences by Noether's Theorem.

  3. The Effects of Fluid Absorption on the Mechanical Properties of Joint Prostheses Components

    NASA Astrophysics Data System (ADS)

    Yarbrough, David; Viano, Ann

    2010-02-01

    Ultra-high-molecular-weight polyethylene (UHMWPE) is the material playing the role of cartilage in human prosthetic joints. Wear debris from UHMWPE is a common reason for joint arthroplasty failure, and the exact mechanism responsible for wear remains an area of investigation. In this study, the microstructure of UHMWPE was examined as a function of fluid absorption. Samples with varying exposure to e-beam radiation (as part of the manufacturing process) were soaked for forty days in saline or artificial synovial fluid, under zero or 100 lbs load. Samples were then tensile-tested according to ASTM D-3895. The post-stressed material was then examined by transmission electron microscopy to evaluate the molecular response to stress, which correlates with macroscopic mechanical properties. Three parameters of the crystalline lamellae were measured: thickness, stacking ratio, and alignment to stress direction. Results indicate that fluid absorption does affect the mechanical properties of UHMWPE at both the microscopic and microscopic levels. )

  4. Tensor Arithmetic, Geometric and Mathematic Principles of Fluid Mechanics in Implementation of Direct Computational Experiments

    NASA Astrophysics Data System (ADS)

    Bogdanov, Alexander; Khramushin, Vasily

    2016-02-01

    The architecture of a digital computing system determines the technical foundation of a unified mathematical language for exact arithmetic-logical description of phenomena and laws of continuum mechanics for applications in fluid mechanics and theoretical physics. The deep parallelization of the computing processes results in functional programming at a new technological level, providing traceability of the computing processes with automatic application of multiscale hybrid circuits and adaptive mathematical models for the true reproduction of the fundamental laws of physics and continuum mechanics.

  5. Colloidal binary mixtures at fluid-fluid interfaces under steady shear: structural, dynamical and mechanical response†

    PubMed Central

    Zell, Zachary A.; Squires, Todd M.; Isa, Lucio

    2015-01-01

    We experimentally study the link between structure, dynamics and mechanical response of two-dimensional (2D) binary mixtures of colloidal microparticles spread at water/oil interfaces. The particles are driven into steady shear by a microdisk forced to rotate at a controlled angular velocity. The flow causes particles to layer into alternating concentric rings of small and big colloids. The formation of such layers is linked to the local, position-dependent shear rate, which triggers two distinct dynamical regimes: particles either move continuously (“Flowing”) close to the microdisk, or exhibit intermittent “Hopping” between local energy minima farther away. The shear-rate-dependent surface viscosity of the monolayers can be extracted from a local interfacial stress balance, giving “macroscopic” flow curves whose behavior corresponds to the distinct microscopic regimes of particle motion. Hopping Regions reveal a higher resistance to flow compared to the Flowing Regions, where spatial organization into layers reduces dissipation. PMID:26347409

  6. Fluid Mechanics of Heart Valves and Their Replacements

    NASA Astrophysics Data System (ADS)

    Sotiropoulos, Fotis; Le, Trung Bao; Gilmanov, Anvar

    2016-01-01

    As the pulsatile cardiac blood flow drives the heart valve leaflets to open and close, the flow in the vicinity of the valve resembles a pulsed jet through a nonaxisymmetric orifice with a dynamically changing area. As a result, three-dimensional vortex rings with intricate topology emerge that interact with the complex cardiac anatomy and give rise to shear layers, regions of recirculation, and flow instabilities that could ultimately lead to transition to turbulence. Such complex flow patterns, which are inherently valve- and patient-specific, lead to mechanical forces at scales that can cause blood cell damage and thrombosis, increasing the likelihood of stroke, and can trigger the pathogenesis of various life-threatening valvular heart diseases. We summarize the current understanding of flow phenomena induced by heart valves, discuss their linkage with disease pathways, and emphasize the research advances required to translate in-depth understanding of valvular hemodynamics into effective patient therapies.

  7. Obstructive renal injury: from fluid mechanics to molecular cell biology.

    PubMed

    Ucero, Alvaro C; Gonçalves, Sara; Benito-Martin, Alberto; Santamaría, Beatriz; Ramos, Adrian M; Berzal, Sergio; Ruiz-Ortega, Marta; Egido, Jesus; Ortiz, Alberto

    2010-04-22

    Urinary tract obstruction is a frequent cause of renal impairment. The physiopathology of obstructive nephropathy has long been viewed as a mere mechanical problem. However, recent advances in cell and systems biology have disclosed a complex physiopathology involving a high number of molecular mediators of injury that lead to cellular processes of apoptotic cell death, cell injury leading to inflammation and resultant fibrosis. Functional studies in animal models of ureteral obstruction using a variety of techniques that include genetically modified animals have disclosed an important role for the renin-angiotensin system, transforming growth factor-β1 (TGF-β1) and other mediators of inflammation in this process. In addition, high throughput techniques such as proteomics and transcriptomics have identified potential biomarkers that may guide clinical decision-making.

  8. Fluid mechanics of directional solidification at reduced gravity

    NASA Technical Reports Server (NTRS)

    Chen, C. F.

    1992-01-01

    The primary objective of the proposed research is to provide additional groundbased support for the flight experiment 'Casting and Solidification Technology' (CAST). This experiment is to be performed in the International Microgravity Laboratory-1 (IML-1) scheduled to be flown on a space shuttle mission scheduled for 1992. In particular, we will provide data on the convective motion and freckle formation during directional solidification of NH4Cl from its aqueous solution at simulated parameter ranges equivalent to reducing the gravity from the sea-level value down to 0.1 g or lower. The secondary objectives of the proposed research are to examine the stability phenomena associated with the onset of freckles and the mechanisms for their subsequent growth and decline (to eventual demise of some) by state-of-the-art imaging techniques and to formulate mathematical models for the prediction of the observed phenomena.

  9. Obstructive renal injury: from fluid mechanics to molecular cell biology

    PubMed Central

    Ucero, Alvaro C; Gonçalves, Sara; Benito-Martin, Alberto; Santamaría, Beatriz; Ramos, Adrian M; Berzal, Sergio; Ruiz-Ortega, Marta; Egido, Jesus; Ortiz, Alberto

    2010-01-01

    Urinary tract obstruction is a frequent cause of renal impairment. The physiopathology of obstructive nephropathy has long been viewed as a mere mechanical problem. However, recent advances in cell and systems biology have disclosed a complex physiopathology involving a high number of molecular mediators of injury that lead to cellular processes of apoptotic cell death, cell injury leading to inflammation and resultant fibrosis. Functional studies in animal models of ureteral obstruction using a variety of techniques that include genetically modified animals have disclosed an important role for the renin-angiotensin system, transforming growth factor-β1 (TGF-β1) and other mediators of inflammation in this process. In addition, high throughput techniques such as proteomics and transcriptomics have identified potential biomarkers that may guide clinical decision-making. PMID:24198613

  10. A novel coarsening mechanism of droplets in immiscible fluid mixtures

    NASA Astrophysics Data System (ADS)

    Shimizu, Ryotaro; Tanaka, Hajime

    2015-06-01

    In our daily lives, after shaking a salad dressing, we see the coarsening of oil droplets suspended in vinegar. Such a demixing process is observed everywhere in nature and also of technological importance. For a case of high droplet density, domain coarsening proceeds with inter-droplet collisions and the resulting coalescence. This phenomenon has been explained primarily by the so-called Brownian-coagulation mechanism: stochastic thermal forces exerted by molecules induce random motion of individual droplets, causing accidental collisions and subsequent interface-tension-driven coalescence. Contrary to this, here we demonstrate that the droplet motion is not random, but hydrodynamically driven by the composition Marangoni force due to an interfacial tension gradient produced in each droplet as a consequence of composition correlation among droplets. This alters our physical understanding of droplet coarsening in immiscible liquid mixtures on a fundamental level.

  11. Fluid Mechanics of Capillary-Elastic Instabilities in Microgravity Environment

    NASA Technical Reports Server (NTRS)

    Grotberg, James B.

    2002-01-01

    The aim of this project is to investigate the closure and reopening of lung airways due to surface tension forces, coupled with airway elasticity. Airways are liquid-lined, flexible tubes and closure of airways can occur by a Rayleigh instability of the liquid lining, or an instability of the elastic support for the airway as the surface tension of the air-liquid interface pulls the tube shut, or both. Regardless of the mechanism, the airway is closed because the liquid lining has created a plug that prevents axial gas exchange. In the microgravity environment, surface tension forces dominate lung mechanics and would lead to more prevalent, and more uniformly distributed air-way closure, thereby creating a potential for respiratory problems for astronauts. Once closed the primary option for reopening an airway is by deep inspiration. This maneuver will pull the flexible airways open and force the liquid plug to flow distally by the incoming air stream. Airway reopening depends to a large extent on this plug flow and how it may lead to plug rupture to regain the continuity of gas between the environment and the alveoli. In addition to mathematical modeling of plug flows in liquid-lined, flexible tubes, this work has involved benchtop studies of propagating liquid plugs down tube networks that mimic the human airway tree. We have extended the work to involve animal models of liquid plug propagation in rat lungs. The liquid is radio-opaque and x-ray video imaging is used to ascertain the movement and distribution of the liquid plugs so that comparisons to theory may be made. This research has other uses, such as the delivery of liquids or drugs into the lung that may be used for surfactant replacement therapy or for liquid ventilation.

  12. [Aging effect on mechanical properties in fluid resin. (Part 1). Affection of residual monomer (author's transl)].

    PubMed

    Horiuchi, A

    1979-07-01

    Aging effect on the mechanical properties in fluid resins was pointed out, but little was studied on this point. Relationship between amount of residual monomer in the samples prepared by fluid resin and the mechanical properties, brinell hardness, tensile strength, were studied. Test pieces just as polymerized in the size were used. Weights of specimens kept at three different circumstances, in the air at 20 degrees C, in a water bath at 37 degrees C and in a desiccator at 11 mmHg and 40 degrees C, was checked at the prescribed time to clarify the amount of residual monomer and the mechanical properties were measured at the same time. Amount of weight loss, due to evaporation of MMA, must improve the mechanical properties. The improvement by postpolymerization could be neglected. Rate of the weight loss suggests that residual monomer must mainly be at the surface. Molecular weight of PMMA, 86.4 X 10(4) did not have any effect on the mechanical properties and on the evaporation rate of monomers from polymerized specimens. To improve the mechanical properties of fluid resin must be to decrease residual monomer as much as possible in the fluid resin especially at the surface area.

  13. Effects of mechanical stimulation induced by compression and medium perfusion on cardiac tissue engineering.

    PubMed

    Shachar, Michal; Benishti, Nessi; Cohen, Smadar

    2012-01-01

    Cardiac tissue engineering presents a challenge due to the complexity of the muscle tissue and the need for multiple signals to induce tissue regeneration in vitro. We investigated the effects of compression (1 Hz, 15% strain) combined with fluid shear stress (10(-2) -10(-1) dynes/cm(2) ) provided by medium perfusion on the outcome of cardiac tissue engineering. Neonatal rat cardiac cells were seeded in Arginine-Glycine-Aspartate (RGD)-attached alginate scaffolds, and the constructs were cultivated in a compression bioreactor. A daily, short-term (30 min) compression (i.e., "intermittent compression") for 4 days induced the formation of cardiac tissue with typical striation, while in the continuously compressed constructs (i.e., "continuous compression"), the cells remained spherical. By Western blot, on day 4 the expression of the gap junction protein connexin 43 was significantly greater in the "intermittent compression" constructs and the cardiomyocyte markers (α-actinin and N-cadherin) showed a trend of better preservation compared to the noncompressed constructs. This regime of compression had no effect on the proliferation of nonmyocyte cells, which maintained low expression level of proliferating cell nuclear antigen. Elevated secretion levels of basic fibroblast growth factor and transforming growth factor-β in the daily, intermittently compressed constructs likely attributed to tissue formation. Our study thus establishes the formation of an improved cardiac tissue in vitro, when induced by combined mechanical signals of compression and fluid shear stress provided by perfusion.

  14. Mechanical-engineering aspects of mirror-fusion technology

    SciTech Connect

    Fisher, D.K.; Doggett, J.N.

    1982-07-15

    The mirror approach to magnetic fusion has evolved from the original simple mirror cell to today's mainline effort: the tandem-mirror machine with thermal barriers. Physics and engineering research is being conducted throughout the world, with major efforts in Japan, the USSR, and the US. At least one facility under construction (MFTF-B) will approach equivalent energy breakeven in physics performance. Significant mechanical engineering development is needed, however, before a demonstration reactor can be constructed. The principal areas crucial to mirror reactor development include large high-field superconducting magnets, high-speed continuous vacuum-pumping systems, long-pulse high-power neutral-beam and rf-plasma heating systems, and efficient high-voltage high-power direct converters. Other areas common to all fusion systems include tritium handling technology, first-wall materials development, and fusion blanket design.

  15. Operating mechanism for dual valves in an internal combustion engine

    SciTech Connect

    Nagahiro, K.; Ishida, A.; Kajiwara, S.

    1987-04-14

    A valve operating mechanism is described for an internal combustion engine having a camshaft, a pair of intake or exhaust valves for each engine cylinder and a rocker shaft, comprising: first and second rocker arms pivotally mounted on the rocker shaft in adjacent relationship and engaging the pair of valves. The first rocker arm engages the camshaft; and piston means in the rocker arms selectively shiftable between positions connecting the rocker arms for pivotal movement in unison and disconnecting the rocker arms for independent movement. The piston means includes two pistons slidably mounted in the first rocker arm with one piston slidable into the second rocker arm for connecting the first and second rocker arms.

  16. Influence of internship toward entrepreneurship interest for mechanical engineering students

    NASA Astrophysics Data System (ADS)

    Sunyoto, Nugroho, Agus; Ulum, Miftakhul

    2017-03-01

    This study was aimed to determine the influence of internship toward students' entrepreneurship interest. Mechanical Engineering Education students from 2013 Batch who had the internship from Engineering Faculty at Semarang State University are the subject of this study. Data was collected through questionnaire and analyzed by simple regression analysis method. The internship subject score and entrepreneurship are categorized in very good level in which the average is 87.08% and 85.61%. However, the influence of internship toward students' interest is categorized in low level in which the average score is 7.9%. Internship section shall encourage students to study entrepreneurship aspects during the internship for entrepreneurship interest improvement and the students' preparation once they graduated. Description scoring standard is needed for scoring the students although they conduct their internship at different locations and companies. The students are highly recommended to conduct an an internship at entrepreneurship-based companies.

  17. Separating Fluid Shear Stress from Acceleration during Vibrations in Vitro: Identification of Mechanical Signals Modulating the Cellular Response

    PubMed Central

    Uzer, Gunes; Manske, Sarah L; Chan, M Ete; Chiang, Fu-Pen; Rubin, Clinton T; Frame, Mary D; Judex, Stefan

    2012-01-01

    The identification of the physical mechanism(s) by which cells can sense vibrations requires the determination of the cellular mechanical environment. Here, we quantified vibration-induced fluid shear stresses in vitro and tested whether this system allows for the separation of two mechanical parameters previously proposed to drive the cellular response to vibration – fluid shear and peak accelerations. When peak accelerations of the oscillatory horizontal motions were set at 1g and 60Hz, peak fluid shear stresses acting on the cell layer reached 0.5Pa. A 3.5-fold increase in fluid viscosity increased peak fluid shear stresses 2.6-fold while doubling fluid volume in the well caused a 2-fold decrease in fluid shear. Fluid shear was positively related to peak acceleration magnitude and inversely related to vibration frequency. These data demonstrated that peak shear stress can be effectively separated from peak acceleration by controlling specific levels of vibration frequency, acceleration, and/or fluid viscosity. As an example for exploiting these relations, we tested the relevance of shear stress in promoting COX-2 expression in osteoblast like cells. Across different vibration frequencies and fluid viscosities, neither the level of generated fluid shear nor the frequency of the signal were able to consistently account for differences in the relative increase in COX-2 expression between groups, emphasizing that the eventual identification of the physical mechanism(s) requires a detailed quantification of the cellular mechanical environment. PMID:23074384

  18. Shape matters: Near-field fluid mechanics dominate the collective motions of ellipsoidal squirmers.

    PubMed

    Kyoya, K; Matsunaga, D; Imai, Y; Omori, T; Ishikawa, T

    2015-12-01

    Microswimmers show a variety of collective motions. Despite extensive study, questions remain regarding the role of near-field fluid mechanics in collective motion. In this paper, we describe precisely the Stokes flow around hydrodynamically interacting ellipsoidal squirmers in a monolayer suspension. The results showed that various collective motions, such as ordering, aggregation, and whirls, are dominated by the swimming mode and the aspect ratio. The collective motions are mainly induced by near-field fluid mechanics, despite Stokes flow propagation over a long range. These results emphasize the importance of particle shape in collective motion.

  19. Mechanics of Undulatory Swimming in a Frictional Fluid

    PubMed Central

    Ding, Yang; Sharpe, Sarah S.; Masse, Andrew; Goldman, Daniel I.

    2012-01-01

    The sandfish lizard (Scincus scincus) swims within granular media (sand) using axial body undulations to propel itself without the use of limbs. In previous work we predicted average swimming speed by developing a numerical simulation that incorporated experimentally measured biological kinematics into a multibody sandfish model. The model was coupled to an experimentally validated soft sphere discrete element method simulation of the granular medium. In this paper, we use the simulation to study the detailed mechanics of undulatory swimming in a “granular frictional fluid” and compare the predictions to our previously developed resistive force theory (RFT) which models sand-swimming using empirically determined granular drag laws. The simulation reveals that the forward speed of the center of mass (CoM) oscillates about its average speed in antiphase with head drag. The coupling between overall body motion and body deformation results in a non-trivial pattern in the magnitude of lateral displacement of the segments along the body. The actuator torque and segment power are maximal near the center of the body and decrease to zero toward the head and the tail. Approximately 30% of the net swimming power is dissipated in head drag. The power consumption is proportional to the frequency in the biologically relevant range, which confirms that frictional forces dominate during sand-swimming by the sandfish. Comparison of the segmental forces measured in simulation with the force on a laterally oscillating rod reveals that a granular hysteresis effect causes the overestimation of the body thrust forces in the RFT. Our models provide detailed testable predictions for biological locomotion in a granular environment. PMID:23300407

  20. 78 FR 37885 - Approval of American Society of Mechanical Engineers' Code Cases

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-24

    ... Mechanical Engineers' Code Cases; Proposed Rule #0;#0;Federal Register / Vol. 78, No. 121 / Monday, June 24... American Society of Mechanical Engineers' Code Cases AGENCY: Nuclear Regulatory Commission. ACTION... revised Code Cases published by the American Society of Mechanical Engineers (ASME). This proposed...

  1. Mechanical cues in orofacial tissue engineering and regenerative medicine.

    PubMed

    Brouwer, Katrien M; Lundvig, Ditte M S; Middelkoop, Esther; Wagener, Frank A D T G; Von den Hoff, Johannes W

    2015-01-01

    Cleft lip and palate patients suffer from functional, aesthetical, and psychosocial problems due to suboptimal regeneration of skin, mucosa, and skeletal muscle after restorative cleft surgery. The field of tissue engineering and regenerative medicine (TE/RM) aims to restore the normal physiology of tissues and organs in conditions such as birth defects or after injury. A crucial factor in cell differentiation, tissue formation, and tissue function is mechanical strain. Regardless of this, mechanical cues are not yet widely used in TE/RM. The effects of mechanical stimulation on cells are not straight-forward in vitro as cellular responses may differ with cell type and loading regime, complicating the translation to a therapeutic protocol. We here give an overview of the different types of mechanical strain that act on cells and tissues and discuss the effects on muscle, and skin and mucosa. We conclude that presently, sufficient knowledge is lacking to reproducibly implement external mechanical loading in TE/RM approaches. Mechanical cues can be applied in TE/RM by fine-tuning the stiffness and architecture of the constructs to guide the differentiation of the seeded cells or the invading surrounding cells. This may already improve the treatment of orofacial clefts and other disorders affecting soft tissues.

  2. The mechanical integrity of in vivo engineered heterotopic bone.

    PubMed

    Warnke, Patrick H; Springer, Ingo N; Acil, Yahya; Julga, Gerrit; Wiltfang, Jörg; Ludwig, Klaus; Russo, Paul A J; Sherry, Eugene; Sivananthan, Sureshan; Hedderich, Jürgen; Terheyden, Hendrik

    2006-03-01

    Recent advances in tissue engineering have aroused interest in growth of heterotopic bone for the repair of skeletal defects. This study demonstrates an in vivo method in minipigs of engineering individual human-sized mandible replacements of heterotopic bone with a mechanical integrity similar to natural bone. Ten individualized mandible replacement scaffolds were created using computer-aided design (CAD) techniques. Five had a resorbable external scaffold made of polylactite mesh (test group 1) and five had had a non-resorbable external scaffold of titanium mesh (test group 2). The mesh scaffolds were loaded each with five BioOss blocks serving as internal scaffolds and 3.5 mg recombinant human Bone Morphogenetic Protein-7. The loaded mesh scaffolds were implanted into the latissimus dorsi muscles of five infant minipigs. After 6 weeks the mandible replacements were harvested. Core biopsy cylinders were taken from the replacements of both test groups and from the natural pig mandibles (control 1). Also, core biopsies from plain BioOss Blocks were gained (control 2). The core biopsy cylinders were loaded axially into a compression test device to evaluate the mechanical compression resistance. Additional specimen underwent histological examination. Both test groups resulted in successful bone induction with degrees of compression resistance [Test 1: 1.62 MPa (SD+/-0.73); Test 2: 1.51 MPa (SD+/-0.56)] statistically insignificant when compared to natural porcine mandibular bone [1.75 MPa (SD+/-0.69)]. This differed significantly from the much lower compression resistance seen in the unadulterated BioOss [0.92 MPa (SD+/-0.04)]. Following this, the in vivo engineered bone has a similar mechanical compression stability as natural bone.

  3. Mechanical Weakening during Fluid Injection in Critically Stressed Sandstones with Acoustic Monitoring

    NASA Astrophysics Data System (ADS)

    David, C.; Dautriat, J. D.; Sarout, J.; Macault, R.; Bertauld, D.

    2014-12-01

    Water weakening is a well-known phenomenon which can lead to subsidence during the production of hydrocarbon reservoirs. The example of the Ekofisk oil field in the North Sea has been well documented for years. In order to assess water weakening effects in reservoir rocks, previous studies have focused on changes in the failure envelopes derived from mechanical tests conducted on rocks saturated either with water or with inert fluids. However, little attention has been paid so far on the mechanical behaviour during the fluid injection stage, like in enhanced oil recovery operations. We studied the effect of fluid injection on the mechanical behaviour of Sherwood sandstone, a weakly-consolidated sandstone sampled at Ladram Bay in UK. In order to highlight possible weakening effects, water and inert oil have been injected into critically-loaded samples to assess their effect on strength and elastic properties and to derive the acoustic signature of the saturation front for each fluid. The specimens were instrumented with 16 ultrasonic P-wave transducers for both passive and active acoustic monitoring during fluid injection and loading. After conducting standard triaxial tests on three samples saturated with air, water and oil respectively, mechanical creep tests were conducted on dry samples loaded at 80% of the compressive strength of the dry rock. While these conditions are kept constant, a fluid is injected at the bottom end of the sample with a low back pressure (0.5 MPa) to minimize effective stress variations during injection. Both water and oil were used as the injected pore fluid in two experiments. As soon as the fluids start to flow into the samples, creep is taking place with a much higher strain rate for water injection compared to oil injection. A transition from secondary creep to tertiary creep is observed in the water injection test whereas in the oil injection test no significant creep acceleration is observed after one pore volume of oil was

  4. Mechanisms Engineering Test Loop - Phase 1 Status Report

    SciTech Connect

    Kultgen, D.; Grandy, C.; Hvasta, M.; Lisowski, D.; Toter, W.; Borowski, A.

    2016-09-01

    This report documents the current status of the Mechanisms Engineering Test Loop (METL) as of the end of FY2016. Currently, METL is in Phase I of its design and construction. Once operational, the METL facility will test small to intermediate-scale components and systems in order to develop advanced liquid metal technologies. Testing different components in METL is essential for the future of advanced fast reactors as it will provide invaluable performance data and reduce the risk of failures during plant operation.

  5. Magnetic field induced tailoring of mechanical behavior of fluid filled micro porous carbon nanotube foam

    NASA Astrophysics Data System (ADS)

    Reddy, Siva Kumar; Mukherjee, Anwesha; Misra, Abha

    2014-06-01

    Compressive loading of the carbon nanotube (CNT) has attracted much attention due to its entangled cellular like structure (CNT foam). This report investigates the mechanical behavior of magnetorheological fluid impregnated micro porous CNT foam that has not been realized before at this scale. Compressive behavior of CNT foam is found to greatly depend on the variation in both fluid viscosity as well as magnetic field intensity. Moreover, maximum achieved stress and energy absorption in CNT foam followed a power law behavior with the magnetic field intensity. Magnetic field induced movement of both CNT and iron oxide particles along the field direction is shown to dominate compressive behavior of CNT foam over highly attractive van der Waals forces between individual CNT. Therefore, this study demonstrates a method for tailoring the mechanical behavior of the fluid impregnated CNT foam.

  6. A Unified Numerical Method for Fluid-Structure Interaction Applied to Human Cochlear Mechanics

    NASA Astrophysics Data System (ADS)

    Böhnke, Frank; Köster, Daniel

    2011-11-01

    A main problem with the numerical simulation of mechanical wave propagation in the cochlea is the coupling of the orthotropic elastic solid (cochlear partition and further structures) and the fluid (perilymph). We developed a unified approach employing velocity and pressure in the entire domain. The numerical approach consists in a finite-volume solver for the coupled solution of equations of motion for fluid and solid working on a single three-dimensional continuum domain. We represent the perilymph as a compressible and viscous fluid with the mechanical properties of water. The cochlear partition is modelled as a 2D membrane whose orthotropicity is represented by a shear modulus. Numerical results of a 3D uncoiled box model show a frequency dependent locus of maximum displacement along the cochlear partition, representing traveling waves.

  7. Organic tissues in rotating bioreactors: fluid-mechanical aspects, dynamic growth models, and morphological evolution.

    PubMed

    Lappa, Marcello

    2003-12-05

    This analysis deals with advances in tissue-engineering models and computational methods as well as with novel results on the relative importance of "controlling forces" in the growth of organic constructs. Specifically, attention is focused on the rotary culture system, because this technique has proven to be the most practical solution for providing a suitable culture environment supporting three-dimensional tissue assemblies. From a numerical point of view, the growing biological specimen gives rise to a moving boundary problem. A "volume-of-fraction" method is specifically and carefully developed according to the complex properties and mechanisms of organic tissue growth and, in particular, taking into account the sensitivity of the construct/liquid interface to the effect of the fluid-dynamic shear stress (it induces changes in tissue metabolism and function that elicit a physiological response from the biological cells). The present study uses available data to introduce a set of growth models. The surface conditions are coupled to the transfer of mass and momentum at the specimen/culture-medium interface and lead to the introduction of a group of differential equations for the nutrient concentration around the sample and for the evolution of tissue mass displacement. The models are then used to show how the proposed surface kinetic laws can predict (through sophisticated numerical simulations) many of the known characteristics of biological tissues grown using rotating-wall perfused vessel bioreactors. This procedure provides a validation of the models and associated numerical method and also gives insight into the mechanisms of the phenomena. The interplay between the increasing size of the tissue and the structure of the convective field is investigated. It is shown that this interaction is essential in determining the time evolution of the tissue shape. The size of the growing specimen plays a critical role with regard to the intensity of convection and

  8. Auxiliary mechanism driving device in a V-type engine

    SciTech Connect

    Asanomi, K.; Ishimi, H.

    1986-10-07

    This patent describes an engine auxiliary mechanism driving device in a V-type engine comprising: an engine crankshaft; a pair of first and second cylinder banks arranged in V-shape and having a first cylinder head and a second cylinder head, respectively, a first camshaft provided on the first cylinder head and having first valve-operating cams for the first cylinders; a second camshaft provided on the second cylinder head having second valve-operating cams for the second cylinders; the first and second camshafts being operatively connected at their one end with the associated end of the crankshaft for synchronized rotation therewith through a transmission means; the first cams on the first camshaft being displaced axially from the second cams on the second camshaft in a manner such that the former are disposed axially more apart from the transmission means than the latter; a crank case at the lower side of the cylinder banks; an oil pump in the crank case adapted to be driven by means of the first camshaft and having a rotation shaft operatively connected with the first camshaft by a driving means; and the driving means comprising a worm gear fixedly mounted on the first camshaft.

  9. Fluid mechanics of human fetal right ventricles from image-based computational fluid dynamics using 4D clinical ultrasound scans.

    PubMed

    Wiputra, Hadi; Lai, Chang Quan; Lim, Guat Ling; Heng, Joel Jia Wei; Guo, Lan; Soomar, Sanah Merchant; Leo, Hwa Liang; Biwas, Arijit; Mattar, Citra Nurfarah Zaini; Yap, Choon Hwai

    2016-12-01

    There are 0.6-1.9% of US children who were born with congenital heart malformations. Clinical and animal studies suggest that abnormal blood flow forces might play a role in causing these malformation, highlighting the importance of understanding the fetal cardiovascular fluid mechanics. We performed computational fluid dynamics simulations of the right ventricles, based on four-dimensional ultrasound scans of three 20-wk-old normal human fetuses, to characterize their flow and energy dynamics. Peak intraventricular pressure gradients were found to be 0.2-0.9 mmHg during systole, and 0.1-0.2 mmHg during diastole. Diastolic wall shear stresses were found to be around 1 Pa, which could elevate to 2-4 Pa during systole in the outflow tract. Fetal right ventricles have complex flow patterns featuring two interacting diastolic vortex rings, formed during diastolic E wave and A wave. These rings persisted through the end of systole and elevated wall shear stresses in their proximity. They were observed to conserve ∼25.0% of peak diastolic kinetic energy to be carried over into the subsequent systole. However, this carried-over kinetic energy did not significantly alter the work done by the heart for ejection. Thus, while diastolic vortexes played a significant role in determining spatial patterns and magnitudes of diastolic wall shear stresses, they did not have significant influence on systolic ejection. Our results can serve as a baseline for future comparison with diseased hearts.

  10. Effects of freezing-induced cell-fluid-matrix interactions on the cells and extracellular matrix of engineered tissues.

    PubMed

    Teo, Ka Yaw; DeHoyos, Tenok O; Dutton, J Craig; Grinnell, Frederick; Han, Bumsoo

    2011-08-01

    The two most significant challenges for successful cryopreservation of engineered tissues (ETs) are preserving tissue functionality and controlling highly tissue-type dependent preservation outcomes. In order to address these challenges, freezing-induced cell-fluid-matrix interactions should be understood, which determine the post-thaw cell viability and extracellular matrix (ECM) microstructure. However, the current understanding of this tissue-level biophysical interaction is still limited. In this study, freezing-induced cell-fluid-matrix interactions and their impact on the cells and ECM microstructure of ETs were investigated using dermal equivalents as a model ET. The dermal equivalents were constructed by seeding human dermal fibroblasts in type I collagen matrices with varying cell seeding density and collagen concentration. While these dermal equivalents underwent an identical freeze/thaw condition, their spatiotemporal deformation during freezing, post-thaw ECM microstructure, and cellular level cryoresponse were characterized. The results showed that the extent and characteristics of freezing-induced deformation were significantly different among the experimental groups, and the ETs with denser ECM microstructure experienced a larger deformation. The magnitude of the deformation was well correlated to the post-thaw ECM structure, suggesting that the freezing-induced deformation is a good indicator of post-thaw ECM structure. A significant difference in the extent of cellular injury was also noted among the experimental groups, and it depended on the extent of freezing-induced deformation of the ETs and the initial cytoskeleton organization. These results suggest that the cells have been subjected to mechanical insult due to the freezing-induced deformation as well as thermal insult. These findings provide insight on tissue-type dependent cryopreservation outcomes, and can help to design and modify cryopreservation protocols for new types of tissues from

  11. Mechanical characteristics of native tendon slices for tissue engineering scaffold

    PubMed Central

    Qin, Ting-Wu; Chen, Qingshan; Sun, Yu-Long; Steinmann, Scott P.; Amadio, Peter C.; An, Kai-Nan; Zhao, Chunfeng

    2014-01-01

    The purpose of this study was to characterize the mechanical behavior of tendon slices with different thicknesses. Tendon slices of 100, 200, 300, 400, and 500 μm thickness were mechanically tested. The 300 μm slices were further tested for strength and modulus after 21,000-cycle fatigue testing under different applied strain levels (0, 1, 3, 5, 8, 10, and 12%). The tendon slice structure, morphology, and viability of bone marrow stromal cells (BMSCs) seeded onto the slices were also examined with histology, scanning electron microscopy, and vital cell labeling, respectively. Tendon slices 300 μm or more in thickness had similar ultimate tensile strength and Young's modulus to the intact tendon bundle. A strain of 5% or less did not cause any structural damage, nor did it change the mechanical properties of a 300 μm-thick tendon slice after 21,000-cycle fatigue testing. BMSCs were viable between and on the tendon slices after 2 weeks in tissue culture. This study demonstrated that, if tendon slices are used as a scaffold for tendon tissue engineering, slices 300 μm or more in thickness would be preferable from a mechanical strength point of view. If mechanical stimulation is performed for seeded-cell preparations, 5% strain or less would be appropriate. PMID:22323314

  12. Natural and engineered nicking endonucleases—from cleavage mechanism to engineering of strand-specificity

    PubMed Central

    Chan, Siu-Hong; Stoddard, Barry L.; Xu, Shuang-yong

    2011-01-01

    Restriction endonucleases (REases) are highly specific DNA scissors that have facilitated the development of modern molecular biology. Intensive studies of double strand (ds) cleavage activity of Type IIP REases, which recognize 4–8 bp palindromic sequences, have revealed a variety of mechanisms of molecular recognition and catalysis. Less well-studied are REases which cleave only one of the strands of dsDNA, creating a nick instead of a ds break. Naturally occurring nicking endonucleases (NEases) range from frequent cutters such as Nt.CviPII (^CCD; ^ denotes the cleavage site) to rare-cutting homing endonucleases (HEases) such as I-HmuI. In addition to these bona fida NEases, individual subunits of some heterodimeric Type IIS REases have recently been shown to be natural NEases. The discovery and characterization of more REases that recognize asymmetric sequences, particularly Types IIS and IIA REases, has revealed recognition and cleavage mechanisms drastically different from the canonical Type IIP mechanisms, and has allowed researchers to engineer highly strand-specific NEases. Monomeric LAGLIDADG HEases use two separate catalytic sites for cleavage. Exploitation of this characteristic has also resulted in useful nicking HEases. This review aims at providing an overview of the cleavage mechanisms of Types IIS and IIA REases and LAGLIDADG HEases, the engineering of their nicking variants, and the applications of NEases and nicking HEases. PMID:20805246

  13. Quantitative ultrasonic evaluation of mechanical properties of engineering materials

    NASA Technical Reports Server (NTRS)

    Vary, A.

    1978-01-01

    Current progress in the application of ultrasonic techniques to nondestructive measurement of mechanical strength properties of engineering materials is reviewed. Even where conventional NDE techniques have shown that a part is free of overt defects, advanced NDE techniques should be available to confirm the material properties assumed in the part's design. There are many instances where metallic, composite, or ceramic parts may be free of critical defects while still being susceptible to failure under design loads due to inadequate or degraded mechanical strength. This must be considered in any failure prevention scheme that relies on fracture analysis. This review will discuss the availability of ultrasonic methods that can be applied to actual parts to assess their potential susceptibility to failure under design conditions.

  14. A variational principle for compressible fluid mechanics: Discussion of the multi-dimensional theory

    NASA Technical Reports Server (NTRS)

    Prozan, R. J.

    1982-01-01

    The variational principle for compressible fluid mechanics previously introduced is extended to two dimensional flow. The analysis is stable, exactly conservative, adaptable to coarse or fine grids, and very fast. Solutions for two dimensional problems are included. The excellent behavior and results lend further credence to the variational concept and its applicability to the numerical analysis of complex flow fields.

  15. Introducing Innovative Approaches to Learning in Fluid Mechanics: A Case Study

    ERIC Educational Resources Information Center

    Gynnild, Vidar; Myrhaug, Dag; Pettersen, Bjornar

    2007-01-01

    The purpose of the current article is to examine the impact of laboratory demonstrations and computer visualizations on learning in a third-year fluid mechanics course at Norwegian University of Science and Technology (NTNU). As a first step, on entering the course, students were exposed to a laboratory demonstration focusing on the nature of…

  16. Neural Mechanisms of Interference Control Underlie the Relationship between Fluid Intelligence and Working Memory Span

    ERIC Educational Resources Information Center

    Burgess, Gregory C.; Gray, Jeremy R.; Conway, Andrew R. A.; Braver, Todd S.

    2011-01-01

    Fluid intelligence (gF) and working memory (WM) span predict success in demanding cognitive situations. Recent studies show that much of the variance in gF and WM span is shared, suggesting common neural mechanisms. This study provides a direct investigation of the degree to which shared variance in gF and WM span can be explained by neural…

  17. Design of a biaxial mechanical loading bioreactor for tissue engineering.

    PubMed

    Bilgen, Bahar; Chu, Danielle; Stefani, Robert; Aaron, Roy K

    2013-04-25

    We designed a loading device that is capable of applying uniaxial or biaxial mechanical strain to a tissue engineered biocomposites fabricated for transplantation. While the device primarily functions as a bioreactor that mimics the native mechanical strains, it is also outfitted with a load cell for providing force feedback or mechanical testing of the constructs. The device subjects engineered cartilage constructs to biaxial mechanical loading with great precision of loading dose (amplitude and frequency) and is compact enough to fit inside a standard tissue culture incubator. It loads samples directly in a tissue culture plate, and multiple plate sizes are compatible with the system. The device has been designed using components manufactured for precision-guided laser applications. Bi-axial loading is accomplished by two orthogonal stages. The stages have a 50 mm travel range and are driven independently by stepper motor actuators, controlled by a closed-loop stepper motor driver that features micro-stepping capabilities, enabling step sizes of less than 50 nm. A polysulfone loading platen is coupled to the bi-axial moving platform. Movements of the stages are controlled by Thor-labs Advanced Positioning Technology (APT) software. The stepper motor driver is used with the software to adjust load parameters of frequency and amplitude of both shear and compression independently and simultaneously. Positional feedback is provided by linear optical encoders that have a bidirectional repeatability of 0.1 μm and a resolution of 20 nm, translating to a positional accuracy of less than 3 μm over the full 50 mm of travel. These encoders provide the necessary position feedback to the drive electronics to ensure true nanopositioning capabilities. In order to provide the force feedback to detect contact and evaluate loading responses, a precision miniature load cell is positioned between the loading platen and the moving platform. The load cell has high accuracies of 0

  18. Design of a Biaxial Mechanical Loading Bioreactor for Tissue Engineering

    PubMed Central

    Bilgen, Bahar; Chu, Danielle; Stefani, Robert; Aaron, Roy K.

    2013-01-01

    We designed a loading device that is capable of applying uniaxial or biaxial mechanical strain to a tissue engineered biocomposites fabricated for transplantation. While the device primarily functions as a bioreactor that mimics the native mechanical strains, it is also outfitted with a load cell for providing force feedback or mechanical testing of the constructs. The device subjects engineered cartilage constructs to biaxial mechanical loading with great precision of loading dose (amplitude and frequency) and is compact enough to fit inside a standard tissue culture incubator. It loads samples directly in a tissue culture plate, and multiple plate sizes are compatible with the system. The device has been designed using components manufactured for precision-guided laser applications. Bi-axial loading is accomplished by two orthogonal stages. The stages have a 50 mm travel range and are driven independently by stepper motor actuators, controlled by a closed-loop stepper motor driver that features micro-stepping capabilities, enabling step sizes of less than 50 nm. A polysulfone loading platen is coupled to the bi-axial moving platform. Movements of the stages are controlled by Thor-labs Advanced Positioning Technology (APT) software. The stepper motor driver is used with the software to adjust load parameters of frequency and amplitude of both shear and compression independently and simultaneously. Positional feedback is provided by linear optical encoders that have a bidirectional repeatability of 0.1 μm and a resolution of 20 nm, translating to a positional accuracy of less than 3 μm over the full 50 mm of travel. These encoders provide the necessary position feedback to the drive electronics to ensure true nanopositioning capabilities. In order to provide the force feedback to detect contact and evaluate loading responses, a precision miniature load cell is positioned between the loading platen and the moving platform. The load cell has high accuracies of 0

  19. Idiopathic cerebrospinal fluid overproduction: case-based review of the pathophysiological mechanism implied in the cerebrospinal fluid production.

    PubMed

    Trevisi, Gianluca; Frassanito, Paolo; Di Rocco, Concezio

    2014-08-28

    Cerebrospinal fluid (CSF) overproduction results from either CSF infection or choroid plexus hypertrophy or tumor, with only a single idiopathic case described so far. We report a unique case of a male infant with Crouzon syndrome who presented with intracranial hypertension, caused by up to 4-fold increase in CSF daily production. Conditions related to CSF overproduction, namely central nervous system infections and choroid plexus hypertrophy or tumor, were ruled out by repeated magnetic resonance imaging and CSF samples. Medical therapy failed to reduce CSF production and the patient underwent several shunting procedures, cranial expansion, and endoscopic coagulation of the choroid plexus. This article thoroughly reviews pertinent literature on CSF production mechanisms and possible therapeutic implications.

  20. Physiologic mechanisms of circulatory and body fluid losses in weightlessness identified by mathematical modeling

    NASA Technical Reports Server (NTRS)

    Simanonok, K. E.; Srinivasan, R. S.; Charles, J. B.

    1993-01-01

    Central volume expansion due to fluid shifts in weightlessness is believed to activate adaptive reflexes which ultimately result in a reduction of the total circulating blood volume. However, the flight data suggests that a central volume overdistention does not persist, in which case some other factor or factors must be responsible for body fluid losses. We used a computer simulation to test the hypothesis that factors other than central volume overdistention are involved in the loss of blood volume and other body fluid volumes observed in weightlessness and in weightless simulations. Additionally, the simulation was used to identify these factors. The results predict that atrial volumes and pressures return to their prebedrest baseline values within the first day of exposure to head down tilt (HDT) as the blood volume is reduced by an elevated urine formation. They indicate that the mechanisms for large and prolonged body fluid losses in weightlessness is red cell hemoconcentration that elevates blood viscosity and peripheral resistance, thereby lowering capillary pressure. This causes a prolonged alteration of the balance of Starling forces, depressing the extracellular fluid volume until the hematocrit is returned to normal through a reduction of the red cell mass, which also allows some restoration of the plasma volume. We conclude that the red cell mass becomes the physiologic driver for a large 'undershoot' of the body fluid volumes after the normalization of atrial volumes and pressures.

  1. Interactive simulations as teaching tools for engineering mechanics courses

    NASA Astrophysics Data System (ADS)

    Carbonell, Victoria; Romero, Carlos; Martínez, Elvira; Flórez, Mercedes

    2013-07-01

    This study aimed to gauge the effect of interactive simulations in class as an active teaching strategy for a mechanics course. Engineering analysis and design often use the properties of planar sections in calculations. In the stress analysis of a beam under bending and torsional loads, cross-sectional properties are used to determine stress and displacement distributions in the beam cross section. The centroid, moments and products of inertia of an area made up of several common shapes (rectangles usually) may thus be obtained by adding the moments of inertia of the component areas (U-shape, L-shape, C-shape, etc). This procedure is used to calculate the second moments of structural shapes in engineering practice because the determination of their moments of inertia is necessary for the design of structural components. This paper presents examples of interactive simulations developed for teaching the ‘Mechanics and mechanisms’ course at the Universidad Politecnica de Madrid, Spain. The simulations focus on fundamental topics such as centroids, the properties of the moment of inertia, second moments of inertia with respect to two axes, principal moments of inertia and Mohr's Circle for plane stress, and were composed using Geogebra software. These learning tools feature animations, graphics and interactivity and were designed to encourage student participation and engagement in active learning activities, to effectively explain and illustrate course topics, and to build student problem-solving skills.

  2. Deconstructing Engineering Education Programmes: The DEEP Project to reform the mechanical engineering curriculum

    NASA Astrophysics Data System (ADS)

    Busch-Vishniac, Ilene; Kibler, Tom; Campbell, Patricia B.; Patterson, Eann; Guillaume, Darrell; Jarosz, Jeffrey; Chassapis, Constantin; Emery, Ashley; Ellis, Glenn; Whitworth, Horace; Metz, Susan; Brainard, Suzanne; Ray, Pradosh

    2011-06-01

    The goal of the Deconstructing Engineering Education Programmes project is to revise the mechanical engineering undergraduate curriculum to make the discipline more able to attract and retain a diverse community of students. The project seeks to reduce and reorder the prerequisite structure linking courses to offer greater flexibility for students. This paper describes the methods used to study the prerequisites and the resulting proposed curriculum revision. The process involved dissecting each course into topics at roughly the level of a line in a syllabus, editing the list of topics, associating prerequisites and successors to each topic and then using a genetic algorithm to produce clusters of topics. The new curriculum, which consists of 12 clusters, each of which could be a full year course, is quite different from the traditional curriculum.

  3. Bi-modular flow characterization in tissue engineering scaffolds using computational fluid dynamics and particle imaging velocimetry.

    PubMed

    De Boodt, Sebastian; Truscello, Silvia; Ozcan, Sezin Eren; Leroy, Toon; Van Oosterwyck, Hans; Berckmans, Daniel; Schrooten, Jan

    2010-12-01

    As part of a tissue engineering (TE) therapy, cell-seeded scaffolds can be cultured in perfusion bioreactors in which the flow-mediated wall shear stress and the nutrient transport are factors that influence in vitro proliferation and osteogenic differentiation of the seeded progenitor cells. In this study both computational fluid dynamics simulations on idealized boundary conditions and circumstances and microparticle image velocimetry measurements on realistic conditions were carried out to quantify the fluid dynamic microenvironment inside a bone TE construct. The results showed that differences between actual and designed geometry and time-dependent character of the fluid flow caused a 19% difference in average fluid velocity and a 27% difference in wall shear stress between simulations and measurements. The computational fluid dynamics simulation enabled higher resolution and three-dimensional fluid flow quantification that could be quantitatively compared with a microparticle image velocimetry measurement. The coupling of numerical and experimental analysis provides a reliable and high-resolution bi-modular tool for quantifying the fluid dynamics that represent the basis to determine the relation between the hydrodynamic environment and cell growth and differentiation within TE scaffolds.

  4. Dispersion coefficients from a field-theoretic renormalization of fluid mechanics.

    PubMed

    Deem, M W; Park, J M

    2001-10-22

    We consider subtle correlations in the scattering of fluid by randomly placed obstacles, which have been suggested to lead to a diverging dispersion coefficient at long times for high Péclet numbers, in contrast to finite mean-field predictions. We develop a new master equation description of the fluid mechanics that incorporates the physically relevant fluctuations, and we treat those fluctuations by a renormalization group procedure. We find a finite dispersion coefficient at low volume fraction of disorder and high Péclet numbers.

  5. Conceptual design of two-phase fluid mechanics and heat transfer facility for spacelab

    NASA Technical Reports Server (NTRS)

    North, B. F.; Hill, M. E.

    1980-01-01

    Five specific experiments were analyzed to provide definition of experiments designed to evaluate two phase fluid behavior in low gravity. The conceptual design represents a fluid mechanics and heat transfer facility for a double rack in Spacelab. The five experiments are two phase flow patterns and pressure drop, flow boiling, liquid reorientation, and interface bubble dynamics. Hardware was sized, instrumentation and data recording requirements defined, and the five experiments were installed as an integrated experimental package. Applicable available hardware was selected in the experiment design and total experiment program costs were defined.

  6. Study of Microfluidic System for Mechanical Property Measurement of Fluid-cell Interface

    NASA Astrophysics Data System (ADS)

    Moon, Ji Young; Lee, Jung Shin; Choi, Se Bin; Yoon, Hong Min; Tanner, Roger I.; Lee, Joon Sang

    2016-11-01

    The system for measuring the mechanical properties of active cell is studied through an integrated microfluidic system for cell separation, alignment and measurement of mechanical properties. A highly efficient lattice Boltzmann method (LBM) was employed to optimize the micro-fluidic system to investigate the interrelations between mechanical properties and various surrounding fluid ingredients which are difficult to observe using current experimental techniques. A combination model of the three dimensional LBM and the immersed boundary method (IBM) were used to simulate these systems. The LBM was used to determine incompressible fluid flow with a regular Eulerian grid. The IBM was used to solve the deformation of cells and matrix fluid interaction with a Lagrangian grid. Highly non-linear results such as cell-cell interactions, fluid-cell interactions, and optical force-cell interactions is studied. National Research Foundation of Korea (NRF) (Grant Number: NRF-2015R1A2A1A15056182, NRF-2015R1A5A1037668).

  7. Electrorheological fluids

    SciTech Connect

    Halsey, T.C.; Martin, J.E.

    1993-10-01

    An electrorheological fluid is a substance whose form changes in the presence of electric fields. Depending on the strength of the field to which it is subjected, an electrorheological fluid can run freely like water, ooze like honey or solidify like gelatin. Indeed, the substance can switch from ne state to another within a few milliseconds. Electrorheological fluids are easy to make; they consist of microscopic particles suspended in an insulating liquid. Yet they are not ready for most commercial applications. They tend to suffer from a number of problems, including structural weakness as solids, abrasiveness as liquids and chemical breakdown, especially at high temperatures. Automotive engineers could imagine, for instance, constructing an electrorheological clutch. It was also hoped that electrorheological fluids would lead to valveless hydraulic systems, in which solidifying fluid would shut off flow through a thin section of pipe. Electrorheological fluids also offer the possibility of a shock absorber that provides response times of milliseconds and does not require mechanical adjustments. 3 refs.

  8. An integrated muscle mechanic-fluid dynamic model of lamprey swimming

    NASA Astrophysics Data System (ADS)

    Hsu, Chia-Yu; Tytell, Eric; Fauci, Lisa

    2009-11-01

    In an effort towards a detailed understanding of the generation and control of vertebrate locomotion, including the role of the CPG and its interactions with reflexive feedback, muscle mechanics, and external fluid dynamics, we study a simple vertebrate, the lamprey. Lamprey body undulations are a result of a wave of neural activation that passes from head to tail, causing a wave of muscle activation. These active forces are mediated by passive structural forces. We present recent results from a model that fully couples a viscous, incompressible fluid with nonlinear muscle mechanics. We measure the dependence of the phase lag between activation wave and mechanical wave as a function of model parameters, such as body stiffness and muscle strength. Simulation results are compared to experiments utilizing both real and synthetic lamprey.

  9. Fluid and solid mechanics in a poroelastic network induced by ultrasound.

    PubMed

    Wang, Peng; Olbricht, William L

    2011-01-04

    We made a theoretical analysis on the fluid and solid mechanics in a poroelastic medium induced by low-power ultrasound. Using a perturbative approach, we were able to linearize the governing equations and obtain analytical solutions. We found that ultrasound could propagate in the medium as a mechanical wave, but would dissipate due to frictional forces between the fluid and the solid phase. The amplitude of the wave depends on the ultrasonic power input. We applied this model to the problem of drug delivery to soft biological tissues by low-power ultrasound and proposed a mechanism for enhanced drug penetration. We have also found the coexistence of two acoustic waves under certain circumstances and pointed out the importance of very accurate experimental determination of the high-frequency properties of brain tissue.

  10. 3-D simulation of soot formation in a direct-injection diesel engine based on a comprehensive chemical mechanism and method of moments

    NASA Astrophysics Data System (ADS)

    Zhong, Bei-Jing; Dang, Shuai; Song, Ya-Na; Gong, Jing-Song

    2012-02-01

    Here, we propose both a comprehensive chemical mechanism and a reduced mechanism for a three-dimensional combustion simulation, describing the formation of polycyclic aromatic hydrocarbons (PAHs), in a direct-injection diesel engine. A soot model based on the reduced mechanism and a method of moments is also presented. The turbulent diffusion flame and PAH formation in the diesel engine were modelled using the reduced mechanism based on the detailed mechanism using a fixed wall temperature as a boundary condition. The spatial distribution of PAH concentrations and the characteristic parameters for soot formation in the engine cylinder were obtained by coupling a detailed chemical kinetic model with the three-dimensional computational fluid dynamic (CFD) model. Comparison of the simulated results with limited experimental data shows that the chemical mechanisms and soot model are realistic and correctly describe the basic physics of diesel combustion but require further development to improve their accuracy.

  11. Rapid simulated gastric fluid digestion of in-seed/grain proteins expressed in genetically engineered crops.

    PubMed

    Schafer, Barry W; Embrey, Shawna K; Herman, Rod A

    2016-11-01

    The speed of simulated gastric digestion of proteins expressed in genetically engineered (GE) crops is commonly used to inform the allergenicity risk assessment. However, persistence of purified proteins in simulated gastric fluid (SGF) is poorly correlated with the allergenic status of proteins. It has been proposed that the plant or food matrix may affect the digestion of proteins and should be considered in interpreting digestion results. Here the SGF digestion of several GE proteins both as purified preparations and in soybean, corn, and cotton seed/grain extracts (in-matrix) are compared. Cry1F, Cry1Ac, phosphinothricin acetyltransferase (PAT), aryloxyalkanoate dioxygenase-1 (AAD-1), aryloxyalkanoate dioxygenase-12 (AAD-12), and double mutant 5-enol pyruvylshikimate-3-phosphate synthase (2mEPSPS) were all found to rapidly digest both as purified protein preparations and in seed/grain extracts from GE crops expressing these proteins. Based on these results, purified protein from microbial sources is a suitable surrogate for proteins in-matrix when conducting SGF digestion studies.

  12. Engineered diamond nanopillars as mobile probes for high sensitivity metrology in fluid

    NASA Astrophysics Data System (ADS)

    Andrich, P.; de Las Casas, C. F.; Heremans, F. J.; Awschalom, D. D.; Aleman, B. J.; Ohno, K.; Lee, J. C.; Hu, E. L.

    2015-03-01

    The nitrogen-vacancy (NV) center`s optical addressability and exceptional spin coherence properties at room temperature, along with diamond`s biocompatibility, has put this defect at the frontier of metrology applications in biological environments. To push the spatial resolution to the nanoscale, extensive research efforts focus on using NV centers embedded in nanodiamonds (NDs). However, this approach has been hindered by degraded spin coherence properties in NDs and the lack of a platform for spatial control of the nanoparticles in fluid. In this work, we combine the use of high quality diamond membranes with a top-down patterning technique to fabricate diamond nanoparticles with engineered and highly reproducible shape, size, and NV center density. We obtain NDs, easily releasable from the substrate into a water suspension, which contain single NV centers exhibiting consistently long spin coherence times (up to 700 μs). Additionally, we demonstrate highly stable, three-dimensional optical trapping of the nanoparticles within a microfluidic circuit. This level of control enables a bulk-like DC magnetic sensitivity and gives access to dynamical decoupling techniques on contactless, miniaturized diamond probes. This work was supported by DARPA, AFOSR, and the DIAMANT program.

  13. Ultrasound Microbubble Treatment Enhances Clathrin-Mediated Endocytosis and Fluid-Phase Uptake through Distinct Mechanisms

    PubMed Central

    Fekri, Farnaz; Delos Santos, Ralph Christian; Karshafian, Raffi

    2016-01-01

    Drug delivery to tumors is limited by several factors, including drug permeability of the target cell plasma membrane. Ultrasound in combination with microbubbles (USMB) is a promising strategy to overcome these limitations. USMB treatment elicits enhanced cellular uptake of materials such as drugs, in part as a result of sheer stress and formation of transient membrane pores. Pores formed upon USMB treatment are rapidly resealed, suggesting that other processes such as enhanced endocytosis may contribute to the enhanced material uptake by cells upon USMB treatment. How USMB regulates endocytic processes remains incompletely understood. Cells constitutively utilize several distinct mechanisms of endocytosis, including clathrin-mediated endocytosis (CME) for the internalization of receptor-bound macromolecules such as Transferrin Receptor (TfR), and distinct mechanism(s) that mediate the majority of fluid-phase endocytosis. Tracking the abundance of TfR on the cell surface and the internalization of its ligand transferrin revealed that USMB acutely enhances the rate of CME. Total internal reflection fluorescence microscopy experiments revealed that USMB treatment altered the assembly of clathrin-coated pits, the basic structural units of CME. In addition, the rate of fluid-phase endocytosis was enhanced, but with delayed onset upon USMB treatment relative to the enhancement of CME, suggesting that the two processes are distinctly regulated by USMB. Indeed, vacuolin-1 or desipramine treatment prevented the enhancement of CME but not of fluid phase endocytosis upon USMB, suggesting that lysosome exocytosis and acid sphingomyelinase, respectively, are required for the regulation of CME but not fluid phase endocytosis upon USMB treatment. These results indicate that USMB enhances both CME and fluid phase endocytosis through distinct signaling mechanisms, and suggest that strategies for potentiating the enhancement of endocytosis upon USMB treatment may improve targeted

  14. Fluid and electrolyte homeostasis during spaceflight: Elucidation of mechanisms in a primate

    NASA Technical Reports Server (NTRS)

    Churchill, Susanne

    1990-01-01

    Although it is now well accepted that exposure to the hypogravic environment of space induces a shift of fluid from the lower extremities toward the upper body, the actual physiological responses to this central volume expansion have not been well characterized. Because it is likely that the fluid and electrolyte response to hypogravity plays a critical role in the development of Cardiovascular Deconditioning, elucidation of these mechanisms is of critical importance. The goal of flight experiment 223, scheduled to fly on SLS-2, is the definition of the basic renal, fluid and electrolyte response to spaceflight in four instrumented squirrel monkeys. The studies were those required to support the development of flight hardware and optimal inflight procedures, and to evaluate a ground-based model for weightlessness, lower body positive pressure (LBPP).

  15. Overview of heat transfer and fluid flow problem areas encountered in stirling engine modeling

    SciTech Connect

    Tew, R.C. Jr.

    1988-02-01

    NASA Lewis Research Center has been managing Stirling engine development programs for over a decade. In addition to contractual programs, this work has included in-house engine testing and development of engine computer models. Attempts to validate Stirling engine computer models with test data have demonstrated that engine thermodynamic losses need better characterization. Various Stirling engine thermodynamic losses and efforts that are underway to characterize these losses are discussed.

  16. Incorporating a Product Archaeology Paradigm across the Mechanical Engineering Curriculum

    ERIC Educational Resources Information Center

    Moore-Russo, Deborah; Cormier, Phillip; Lewis, Kemper; Devendorf, Erich

    2013-01-01

    Historically, the teaching of design theory in an engineering curriculum has been relegated to a senior capstone design experience. Presently, however, engineering design concepts and courses can be found through the entirety of most engineering programs. Educators have recognized that engineering design provides a foundational platform that can…

  17. Effects of mechanical dispersion on the morphological evolution of a chemical dissolution front in a fluid-saturated porous medium

    NASA Astrophysics Data System (ADS)

    Chen, Jui-Sheng; Liu, Chen-Wuing; Lai, Geng-Xin; Ni, Chuen-Fa

    2009-06-01

    SummaryThe dissolution-induced finger or wormhole patterns in porous medium or fracture rock play a crucial role in a variety of scientific, industrial, and engineering practices. Although previous studies have extensively presented a number of numerical models which couples a system of nonlinear governing equations of porosity change due to mineral dissolution, the conservations of groundwater flow and transport of chemical species to investigate the morphological pattern of a chemical dissolution front within a fluid-saturated porous medium, whereas the mechanical dispersion effect has generally been neglected in the model development. This study addresses the effects of mechanical dispersion on the morphological evolution of a chemical dissolution front for a variety of cases. Mechanical dispersion processes is incorporated with the coupled nonlinear governing equation system so as to rebuild a newly numerical model. The results of numerical simulations demonstrate that mechanical dispersion has pronounced impacts on the morphological pattern of the chemical dissolution front. For single local non-uniformity case, mechanical dispersion reduces the finger length of an unstable single-fingering front or retains the shape of a stable planar front while speeding up the front advancement. In the case of two local non-uniformities, adding mechanical dispersion with different flow conditions can yield one of the following results: (1) the shape of the stable planar front is maintained but its advancement is accelerated; (2) the shape of the unstable single-fingering front is maintained but its length is reduced; (3) the unstable double-fingering front is merged into an unstable single-fingering front; and (4) the shape of the unstable double-fingering front is preserved but its fingering length is reduced. A comparison between the behavior diagrams of dissolution front morphology (with and without considering mechanical dispersion) shows that the double-fingering front

  18. Fluid load support and contact mechanics of hemiarthroplasty in the natural hip joint.

    PubMed

    Pawaskar, Sainath Shrikant; Ingham, Eileen; Fisher, John; Jin, Zhongmin

    2011-01-01

    The articular cartilage covering the ends of the bones of diarthrodial synovial joints is thought to have evolved so that the loads are transferred under different and complex conditions, with a very high degree of efficiency and without compromising the structural integrity of the tissue for the life of an individual. These loading conditions stem from different activities such as walking, and standing. The integrity of cartilage may however become compromised due to congenital disease, arthritis or trauma. Hemiarthroplasty is a potentially conservative treatment when only the femoral cartilage is affected as in case of femoral neck fractures. In hemiarthroplasty, a metallic femoral prosthesis is used to articulate against the natural acetabular cartilage. It has also been hypothesized that biphasic lubrication is the predominant mechanism protecting the cartilage through a very high fluid load support which lowers friction. This may be altered due to hemiarthroplasty and have a direct effect on the frictional shear stresses and potentially cartilage degradation and wear. This study modelled nine activities of daily living and investigated the contact mechanics of a hip joint with a hemiarthroplasty, focussing particularly on the role of the fluid phase. It was shown that in most of the activities studied the peak contact stresses and peak fluid pressures were in the superior dome or lateral roof of the acetabulum. Total fluid load support was very high (~90%) in most of the activities which would shield the solid phase from being subjected to very high contact stresses. This was dependent not only on the load magnitude but also the direction and hence on the location of the contact area with respect to the cartilage coverage. Lower fluid load support was found when the contact area was nearer the edges where the fluid drained easily.

  19. Influence of fluid and volume state on PaO2 oscillations in mechanically ventilated pigs.

    PubMed

    Bodenstein, Marc; Bierschock, Stephan; Boehme, Stefan; Wang, Hemei; Vogt, Andreas; Kwiecien, Robert; David, Matthias; Markstaller, Klaus

    2013-03-01

    Varying pulmonary shunt fractions during the respiratory cycle cause oxygen oscillations during mechanical ventilation. In artificially damaged lungs, cyclical recruitment of atelectasis is responsible for varying shunt according to published evidence. We introduce a complimentary hypothesis that cyclically varying shunt in healthy lungs is caused by cyclical redistribution of pulmonary perfusion. Administration of crystalloid or colloid infusions would decrease oxygen oscillations if our hypothesis was right. Therefore, n=14 mechanically ventilated healthy pigs were investigated in 2 groups: crystalloid (fluid) versus no-fluid administration. Additional volume interventions (colloid infusion, blood withdrawal) were carried out in each pig. Intra-aortal PaO2 oscillations were recorded using fluorescence quenching technique. Phase shift of oxygen oscillations during altered inspiratory to expiratory (I:E) ventilation ratio and electrical impedance tomography (EIT) served as control methods to exclude that recruitment of atelectasis is responsible for oxygen oscillations. In hypovolemia relevant oxygen oscillations could be recorded. Fluid and volume state changed PaO2 oscillations according to our hypothesis. Fluid administration led to a mean decline of 105.3 mmHg of the PaO2 oscillations amplitude (P<0.001). The difference of the amplitudes between colloid administration and blood withdrawal was 62.4 mmHg in pigs not having received fluids (P=0.0059). Fluid and volume state also changed the oscillation phase during altered I:E ratio. EIT excluded changes of regional ventilation (i.e., recruitment of atelectasis) to be responsible for these oscillations. In healthy pigs, cyclical redistribution of pulmonary perfusion can explain the size of respiratory-dependent PaO2 oscillations.

  20. Reservoir Engineering of Two-mode Correlations in Mechanical Resonators

    NASA Astrophysics Data System (ADS)

    Chang, Laura; Patil, Yogesh Sharad; Chakram, Srivatsan; Vengalattore, Mukund

    2015-05-01

    Nonlinear mechanical interactions in the quantum limit enable the manipulation and control of phonons in a manner akin to quantum optics in nonlinear media. We demonstrate, for the first time, strong quantum-compatible multimode nonlinearities in a low-loss mechanical resonator that is amenable to ground state optomechanical cooling, room temperature quantum control and quantum limited detection. These nonlinearities arise from substrate-mediated interactions between distinct modes of the resonator. We develop a model for this nonlinearity that accurately describes the experimental observations over three orders of magnitude in dynamic range, demonstrating the robustness and fidelity of the engineered nonlinear interactions. We use this nonlinearity to realize a mechanical nondegenerate parametric amplifier, and use it to demonstrate two-mode thermomechanical noise squeezing. Our work opens new opportunities for nonlinear approaches to quantum metrology, transduction between optical and phononic fields, and the quantum manipulation of phononic degrees of freedom. This work is supported by the DARPA QuASAR program through a grant from the ARO and an NSF INSPIRE award.