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Sample records for mechanics fluids engineering

  1. 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)

  2. Fluid Mechanics and Hydrology

    NASA Astrophysics Data System (ADS)

    Osterkamp, W. R.; Gray, J. R.; Narayanan, M.

    2002-12-01

    Present day Engineers need to understand water, its properties, its distribution as well as its movement. Certain engineering disciplines may require a course in Hydraulics and Hydrology. However, most other disciplines require courses in Fluid Mechanics and Thermodynamics. The author believes Hydrology is an essential knowledge that most engineers should possess, regardless of their discipline. Water is consumed or circulated in huge quantities in certain types of industries and location of water resources / supply may play a key role in the selection of a future factory site. Pulp and Paper Manufacturing Industries, Chemical Industries, Heat Treatment Facilities are just a few that one can mention. A typical Engineering Fluid Mechanics Course normally covers the broad discipline of Engineering Mechanics that is concerned with the behavior of Liquids and gases at rest or in motion. Water, of course is one of the liquids discussed. Regardless, Engineers are totally ignorant of the subject matter of Hydrology or the Hydrologic Cycle and their importance in the twenty-first century Engineering Environment. In this short paper, the author outlines the methods of successfully incorporating Hydrology into an Engineering Fluid Mechanics Course.

  3. The development of a transparent cylinder engine for piston engine fluid mechanics research

    SciTech Connect

    Richman, R.M.; Reynolds, W.C.

    1984-01-01

    The development of a unique flow visualization engine is discussed. The new research engine, called the Flow Diagnostics Engine (FDE), is a singlecylinder engine with a transparent cylinder made from single-crystal sapphire. In contrast to previous efforts, the FDE has an internal geometry very similar to that of production engines. A computer-controlled valveactuation system is used on the FDE. The valve actuators are fast electro-hydraulic devices which, with a minicomputer, provide complete control over the valve motion. To visualize the flows in the engine cylinder, a special Schlieren system was developed and demonstrated. In the new visualization system, a holographic optical element is used to correct system abberations. To demonstrate the feasibility and usefulness of the FDE system, flows in both conventional and swirl engine geometries were visualized and recorded with high-speed cinematography. The visualization provides qualitative information about the flow and allows observation of: the development and motions of large recirculation zones during the intake event; the appearance of small-scale turbulence and the changes in scale caused by compression and expansion; the expansion of ring crevice gases into the cylinder during the beginning of the event; and the large-scale motions associated with intake swirl. The FDE system is very versatile and can accommodate a wide variety of engine geometries, operating conditions, and optical diagnostics.

  4. 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.

  5. 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.

  6. 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.

  7. Fluid mechanics of combustion systems; Proceedings of the Fluids Engineering Conference, Boulder, CO, June 22, 23, 1981

    NASA Astrophysics Data System (ADS)

    Morel, T.; Lohmann, R. P.; Rackley, J. M.

    1981-01-01

    The work examines such topics as the parametric variations of a heat balanced engine, the calculation of pulverized coal combustion in an axisymmetrical furnace, optical tomography for diagnostics in combusting flows, the numerical simulation of swirling flow in a cyclone chamber, and the flow aerodynamics modeling of an MHD swirl combustor. Consideration is also given to the interaction between strain fields and flames in spark ignition engines, the flow and combustion characteristics of turbulent reacting flames, the application of numerical modeling to gas turbine combustor development problems, and the prediction of swirling flow fields in axisymmetric combustor geometries.

  8. Design of a nanomechanical fluid control valve based on functionalized silicon cantilevers: coupling molecular mechanics with classical engineering design

    NASA Astrophysics Data System (ADS)

    Solares, Santiago D.; Blanco, Mario; Goddard, William A., III

    2004-11-01

    Process engineering design relies on a host of mechanical devices that enable transport phenomena to take place under controlled conditions. These devices include pipes, valves, pumps, chemical reactors, heat exchangers, packed columns, etc. Mass, energy, and momentum transfer will also be essential phenomena in nanoprocess engineering, particularly at the interface between micro- and nanodevices. Control valves are one of the most fundamental components. In this paper we explore the design of a silicon cantilever valve for fluid transport control at the molecular level (34.5-70 nm in length). We utilize design elements that can be synthesized with existing or emerging chemical and solid state fabrication methods. Thus, the valve is constructed with functionalized silicon surfaces, single-wall carbon nanotubes, and organic monolayers. While molecular mechanics design limitations were overcome with help from classical engineering approximations, nonlinear effects, such as nanotube crimping (for an in-line valve design), are accounted for through full-physics atomistic simulations. Optimal design geometries and operating deflection ranges have been estimated for a device containing over 75 000 atoms.

  9. Method for optimizing the mechanical output of a fluid pressure free piston engine

    SciTech Connect

    Dibrell, E.W.; Schaich, W.A.

    1988-07-05

    The method is described for minimizing rotational speed variations of a centrifugal piston expander engine comprising the steps of: (1) supplying a pressured gas to a centrifugal piston expander engine having a rotatable output element and a discharge conduit for cooled exhaust gas; (2) expanding and cooling the pressured gas in the centrifugal piston expander engine to produce cyclically varying oppositely directed, positive and negative torques on the rotatable output shaft; (3) driving a rotary load in the positive torque direction by the rotatable output element through one rotatable element of a unidirectional clutch having two rotating elements relatively movable in only the negative torque direction; and (4) connecting a battery operated motor-generator unit to the rotatable output shaft to supplement the rotary speed of the output shaft during periods of negative torque output by the centrifugal piston expander engine and to recharge the battery during periods of maximum positive torque output of the centrifugal expander engine.

  10. 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…

  11. 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

  12. Fluid mechanics measurements

    NASA Astrophysics Data System (ADS)

    Goldstein, R. J.

    The advent of sophisticated numerical methods for the study and prediction of fluid flows has not diminished, but rather enhanced, the need for improved measurement techniques, especially in the cases of turbulent and three-dimensional flow studies. Attention is presently given to examples of fluid mechanics measurements concerned with wind tunnels, propeller vibrations, and turbulent mixing layers, the physical laws of fluid mechanics, the uses of differential pressure measurements, the capabilities of thermal anemometers and laser velocimeters, and metering devices for volume flow measurements. Also discussed are flow visualization by direct injection, shadowgraph, schlieren, and interferometric techniques of flow measurement, measurements in non-Newtonian fluids, wall shear stress measurements, and two-phase flow techniques for gas-liquid systems.

  13. The Hybrid Sterling Engine: boosting photovoltaic efficiency and deriving mechanical work from fluid expansion and heat capture

    NASA Astrophysics Data System (ADS)

    Beets, Nathan; Wake Forest CenterNanotechnology; Molecular Materials Team; Fraunhofer Institute Collaboration

    2015-11-01

    Two major problems with many third generation photovoltaics is their complex structure and greater expense for increased efficiency. Spectral splitting devices have been used by many with varying degrees of success to collect more and more of the spectrum, but simple, efficient, and cost-effective setups that employ spectral splitting remain elusive. This study explores this problem, presenting a solar engine that employs stokes shifting via laser dyes to convert incident light to the wavelength bandgap of the solar cell and collects the resultant infrared radiation unused by the photovoltaic cell as heat in ethylene glycol or glycerin. When used in conjunction with micro turbines, fluid expansion creates mechanical work, and the temperature difference between the cell and the environment is made available for use. The effect of focusing is also observed as a means to boost efficiency via concentration. Experimental results from spectral scans, vibrational voltage analysis of the PV itself and temperature measurements from a thermocouple are all compared to theoretical results using a program in Mathematica written to model refraction and lensing in the devices used, a quantum efficiency test of the cells, the absorption and emission curves of the dues used to determine the spectrum shift, and the various equations for fill factor, efficiency, and current in different setups. An efficiency increase well over 50% from the control devices is observed, and a new solar engine proposed.

  14. Quantitative, single shot, two-dimensional spontaneous Raman measurements for fluid mechanics and engine applications

    NASA Astrophysics Data System (ADS)

    Kyritsis, Dimitrios Constantinou

    Spontaneous Raman Scattering was used for quantitative, two-dimensional, single-shot measurements of species concentration in optically accessible confinements and in an experimental single-cylinder internal combustion engine. The study comprised three parts. In the first part, the technique was used for methane concentration measurements in a laminar jet issuing into compressed nitrogen (10 bar, 293 K). The injection Reynolds number was 550. Initial results showed unexpected structures in the acquired concentration profiles. Thus, the steadiness of the laminar flow was confirmed with high speed shadowgraph movies and laser induced fluorescence measurements. Eventually, it was proven that the structures were due to characteristics of the camera system. A technique was then devised for the proper acquisition and processing of data and spatial resolution of 500 mum was achieved. Methane number density equal to 12% of the number density of pure methane (0.247E+26 molecules/msp3) was then measured with a signal-to-noise ratio of approximately 3. The measurements were compared with the results of direct numerical simulation of the flow field. In the second part, measurements in a laminar hydrogen jet were taken. Because of the reduced Raman signal of hydrogen, the incident laser power was increased by installing the pressurized chamber within the laser cavity. This yielded an increase in power by a factor of 2.5. For the measurement of the laser sheet intensity in the laser cavity, insertion of a fluorescent dye cell and Rayleigh scattering were used and evaluated comparatively. The precise location of the waist of the laser sheet was determined by trial and error. The spatial resolution of the measurements was 650 mum and a number density of 0.371E+26 hydrogen molecules/msp3 was measured with a signal-to-noise ratio of 3. The measurements were again compared with results of direct numerical simulation. In the third part, the feasibility of two-dimensional single-shot Spontaneous Raman measurements in an engine cylinder was established. Measurements of methane concentration after direct injection in the cylinder of an experimental single-cylinder engine were taken. The engine was not fired to avoid laser induced incandescence interference. The spatial resolution was limited to 800 mum by the thickness of the laser sheet. Fast mixing of the methane jet was documented but a precise evaluation of the equivalence ratio was beyond the resolution of this first attempt. Finally, existing hardware for data acquisition and algorithms for two dimensional data reduction were reviewed and recommendations were made for the extraction of quantitative information from two-dimensional, single-shot Spontaneous Raman signals which are weak and noisy.

  15. Relativistic viscoelastic fluid mechanics

    SciTech Connect

    Fukuma, Masafumi; Sakatani, Yuho

    2011-08-15

    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.

  16. Proceedings of industrial applications of fluid mechanics

    SciTech Connect

    Sherif, S.A. ); Morrow, T.B. ); Marshall, L.R. ); Dalton, C. )

    1990-01-01

    The is the fourth Forum on Industrial Applications of Fluid Mechanics sponsored by the Fluid Mechanics Committee of the ASME Fluids Engineering Division. The Forum objective is to promote the discussion and interchange of current information on developing and state-of-the-art applications of fluid mechanics technology. The program is organized as a technical forum to encourage the presentation of new ideas, especially those which may be so innovative that a conservative review process might delay their dissemination to the fluids engineering community. Four sessions and a total of 17 papers are scheduled for this program. Three of the four sessions were devoted to contributed papers, while the fourth is a panel discussion with three invited presentations. All papers were reviewed editorially to assure that they are related to the forum theme The papers were not evaluated technically, and therefore carry no endorsement from the Fluid Mechanics Committee or the Fluids Engineering Division with regard to peer evaluation. The forum presentations will focus on specific applications of fluid mechanics technology. Lively discussion of the papers is encouraged at the forum. The Fluid Mechanics Committee plans to sponsor a forum with an industrial applications theme each year at the ASME Winter Annual Meeting. In 1991, the scope of the forum will be enlarged to include the topic of textile applications of fluid mechanics, and another panel session featuring speakers with industrial experience in different areas of fluid mechanics applications. In future years, it is anticipated that the forum will solicit papers from other areas where fluid mechanics technology is applied.

  17. 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. PMID:23005525

  18. Fluid mechanics revisited

    NASA Astrophysics Data System (ADS)

    Brenner, Howard

    2006-10-01

    Öttinger's recent nontraditional incorporation of fluctuations into the formulation of the friction matrix appearing in the phenomenological GENERIC theory of nonequilibrium irreversible processes is shown to furnish transport equations for single-component gases and liquids undergoing heat transfer which support the view that revisions to the Navier-Stokes-Fourier (N-S-F) momentum/energy equation set are necessary, as empirically proposed by the author on the basis of an experimentally supported theory of diffuse volume transport. The hypothesis that the conventional N-S-F equations prevail without modification only in the case of “incompressible” fluids, where the density ρ of the fluid is uniform throughout, serves to determine the new phenomenological parameter α‧ appearing in the GENERIC friction matrix. In the case of ideal gases the consequences of this constitutive hypothesis are shown to yield results identical to those derived theoretically by Öttinger on the basis of a “proper” coarse-graining of Boltzmann's kinetic equation. A major consequence of the present work is that the fluid's specific momentum density v is equal to its volume velocity vv, rather than to its mass velocity vm, contrary to current views dating back 250 years to Euler. In the case of rarefied gases the proposed modifications are also observed to agree with those resulting from Klimontovich's molecularly based, albeit ad hoc, self-diffusion addendum to Boltzmann's collision integral. Despite the differences in their respective physical models-molecular vs. phenomenological-the role played by Klimontovich's collisional addition to Boltzmann's equation in modifying the N-S-F equations is noted to constitute a molecular counterpart of Öttinger's phenomenological fluctuation addition to the GENERIC friction matrix. Together, these two theories collectively recognize the need to address multiple- rather than single- encounter collisions between a test molecule and its neighbors when formulating physically satisfactory statistical-mechanical theories of irreversible transport processes in gases. Overall, the results of the present work implicitly support the unorthodox view, implicit in the GENERIC scheme, that the translation of Newton's discrete mass-point molecular mechanics into continuum mechanics, the latter as embodied in the Cauchy linear momentum equation of fluid mechanics, cannot be correctly effected independently of the laws of thermodynamics. While Öttinger's modification of GENERIC necessitates fundamental changes in the foundations of fluid mechanics in regard to momentum transport, no basic changes are required in the foundations of linear irreversible thermodynamics (LIT) beyond recognizing the need to add volume to the usual list of extensive physical properties undergoing transport in single-species fluid continua, namely mass, momentum and energy. An alternative, nonGENERICally based approach to LIT, derived from our findings, is outlined at the conclusion of the paper. Finally, our proposed modifications of both Cauchy's linear momentum equation and Newton's rheological constitutive law for fluid-phase continua are noted to be mirrored by counterparts in the literature for solid-phase continua dating back to the classical interdiffusion experiments of Kirkendall and their subsequent interpretation by Darken in terms of diffuse volume transport.

  19. 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.

  20. Fluid Mechanics of Papermaking

    NASA Astrophysics Data System (ADS)

    Lundell, Fredrik; Söderberg, L. Daniel; Alfredsson, P. Henrik

    2011-01-01

    Papermaking is to a large extent a multiphase flow process in which the structure of the material and many of the relevant properties of the final product are determined by the interaction between water and the wood fibers. The dominant feature of a suspension composed of wood fibers and water is its inherent propensity to form bundles of mechanically entangled fibers, known as fiber flocs. However, the phenomena apparent throughout the papermaking process are not unique but in fact have a generic fluid dynamical nature.

  1. Internal fluid mechanics research

    NASA Astrophysics Data System (ADS)

    Reid, Lonnie; Povinelli, Louis A.

    1991-03-01

    The Internal Fluid Mechanics Division is responsible for computational and experimental research on the internal aerothermodynamics of aeronautical and space propulsion systems. The research focuses on advancing the understanding of the relevant physics associated with improving the state of technology for propulsion system components. Research consists of the development of fast and accurate computational tools and models, the verification of these CFD tools and models through benchmark experiments, and their application to realistic propulsion system components. Advanced computational technologies are used to enhance, accelerate, and integrate computational and experimental research. The presentations summarize ongoing work and indicate emphasis in three major research thrusts, namely, inlets, ducts, and nozzles; turbomachinery; and chemical reacting flows.

  2. 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

  3. 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 the Euler, Froude, Reynolds, Weber, and Cauchy numbers are defined as essential tools for interpreting and using experimental data. The derivations of the energy and momentum equations are treated in detail. One-dimensional equations for steady nonuniform flow are developed, and the restrictions applicable to the equations are emphasized. Conditions of uniform and gradually varied flow are discussed, and the origin of the Chezy equation is examined in relation to both the energy and the momentum equations. The inadequacy of all uniform-flow equations as a means of describing gradually varied flow is explained. Thus, one of the definitive problems of river hydraulics is analyzed in the light of present knowledge. This report is the outgrowth of a series of short schools conducted during the spring and summer of 1953 for engineers of the Surface Water Branch, Water Resources Division, U. S. Geological Survey. The topics considered are essentially the same as the topics selected for inclusion in the schools. However, in order that they might serve better as a guide and outline for informal study, the arrangement of the writer's original lecture notes has been considerably altered. The purpose of the report, like the purpose of the schools which inspired it, is to build a simple but strong framework of the fundamentals of fluid mechanics. It is believed that this framework is capable of supporting a detailed analysis of most of the practical problems met by the engineers of the Geological Survey. It is hoped that the least accomplishment of this work will be to inspire the reader with the confidence and desire to read more of the recent and current technical literature of modern fluid mechanics.

  4. 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.

  5. 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…

  6. A Design-Oriented Approach to the Integration of Thermodynamics, Fluid Mechanics, and Heat Transfer in the Undergraduate Mechanical Engineering Curriculum.

    ERIC Educational Resources Information Center

    Whale, MacMurray D.; Cravalho, Ernest G.

    This paper describes two parallel efforts that attempt to implement a new approach to the teaching of thermal fluids engineering. In one setting, at the Massachusetts Institute of Technology (MIT), the subject matter is integrated into a single year-long subject at the introductory level. In the second setting, at Victoria (British Columbia,…

  7. 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.

  8. 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.

  9. 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…

  10. Mechanical Engineering Technology Curriculum.

    ERIC Educational Resources Information Center

    Georgia State Univ., Atlanta. Dept. of Vocational and Career Development.

    This guide offers information and procedures necessary to train mechanical engineering technicians. Discussed first are the rationale and objectives of the curriculum. The occupational field of mechanical engineering technology is described. Next, a curriculum model is set forth that contains information on the standard mechanical engineering…

  11. 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.

  12. 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. PMID:25634115

  13. 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…

  14. 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.

  15. 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.

  16. 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)

  17. 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.

  18. 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)

  19. 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 papers were accepted for Proceedings published in the Journal of Physics: Conference Series. The total number of submitted and accepted papers for this year's conference represents a significant increase over previous Fluid Mechanics Conferences, and has expanded its initial national character and borders which speaks to the great vitality of fluid mechanics. We hope that these proceedings will be used not only as a document of the event but also to assess achievements and new paths to be taken in fluid mechanics research. Finally, we would like to congratulate the winners of the 2014 Professor Janusz W Elsner Competition Ruri Hidema from Japan, Fernando Tejero from Spain and Lukasz Laniewski-Wollk from Poland. Acknowledgements We would like to express grateful appreciation to our colleagues from the Polish Academy of Sciences, Committee of Mechanics, as well as to the International Scientific Committee i.e. Members and the Advisory Board. Their advice and efforts have helped us to overcome the problems normally associated with organising international meetings. Special thanks goes to the reviewers for their work in encouraging the submission of papers and the subsequent review of all papers. Their contribution cannot be overestimated. The 21st Fluid Mechanics Conference was organised by AGH University of Science and Technology, the Polish Academy of Sciences the Committee of Mechanics and the AGH-UST Foundation. Proceedings was published in the Journal of Physics: Conference Series. The demanding work involved could not have been done without the contribution of so many individuals from all institutions as well as numerous external co-workers. Without their extremely valuable help such a meeting would have been impossible. Thank you all so much! Details of the committees are available in the PDF

  20. 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.

  1. 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…

  2. 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. PMID:15255773

  3. Size-Dependent Fluid Mechanics

    NASA Astrophysics Data System (ADS)

    Hadjesfandiari, Ali; Hajesfandiari, Arezoo; Dargush, Gary

    2013-11-01

    Classical fluid mechanics provides a reasonable basis for analyzing the behavior of fluid flow at the macro scale. However, experiments show that the behavior of fluid in small scales is different from their behavior at macro scales. An additional concern relates to the absence of a length scale in the governing Navier-Stokes equations, when the present description of turbulence seems to need the clear definition of a characteristic size. Consequently, there is need for a more complete fluid dynamics, which spans many scales and, of course, must reduce to classical fluid mechanics for flows with macro-scale size. Here we develop the consistent size-dependent fluid mechanics by discovering the skew-symmetric character of couple stress tensor. As a result, the skew-symmetric mean curvature rate vector as the consistent measure of deformation is introduced. It is demonstrated that this theory may provide a basis for fundamental studies of flows at the finest scales for which a continuum representation is valid and, perhaps, for gaining additional insight into the problem of turbulence.

  4. Proceedings of industrial applications of fluid mechanics '91

    SciTech Connect

    Morrow, T.B.

    1991-01-01

    This book reports on the fifth Forum on Industrial Applications of Fluid Mechanics sponsored by the Fluid Applications and Systems Technical Committee of the ASME Fluids Engineering Division. The Forum objective is to promote the discussion and interchange of current information on developing and state-of-the-art applications of fluid mechanics technology. The program is organized as a technical forum to encourage the presentation of new ideas, especially those which may be so innovative that a conservative review process might delay their dissemination to the fluids engineering community.

  5. 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.

  6. 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…

  7. 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.

  8. Mechanical Properties of Electrorheological Fluids

    NASA Astrophysics Data System (ADS)

    Zhao, He-ping; Liu, Zheng-you; Shen, Jia-rui; Liu, You-yan; P, M. Hui

    1998-03-01

    The Rayleigh identity based on a multipole expansion theory is extended to analyze the mechanical properties of electroheological fluids. Evaluation of the effective dielectric constant is emphasized. The dependence of the shear stress on the shear strain and the shear modulus for chains of particles arranged on a square lattice are presented.

  9. Fluid Mechanics and Homeland Security

    NASA Astrophysics Data System (ADS)

    Settles, Gary S.

    2006-01-01

    Homeland security involves many applications of fluid mechanics and offers many opportunities for research and development. This review explores a wide selection of fluids topics in counterterrorism and suggests future directions. Broad topics range from preparedness and deterrence of impending terrorist attacks to detection, response, and recovery. Specific topics include aircraft hardening, blast mitigation, sensors and sampling, explosive detection, microfluidics and labs-on-a-chip, chemical plume dispersal in urban settings, and building ventilation. Also discussed are vapor plumes and standoff detection, nonlethal weapons, airborne disease spread, personal protective equipment, and decontamination. Involvement in these applications requires fluid dynamicists to think across the traditional boundaries of the field and to work with related disciplines, especially chemistry, biology, aerosol science, and atmospheric science.

  10. 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…

  11. [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.

  12. 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.

  13. 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.

  14. 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.

  15. Engineering fluid flow using sequenced microstructures.

    PubMed

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

    2013-01-01

    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. PMID:23652014

  16. Fluid Mechanics of Tropical Cyclones

    NASA Astrophysics Data System (ADS)

    Lighthill, James, Sir

    Typhoons in the northwest Pacific and hurricanes in the northeast Atlantic are particular instances of a global phenomenon with frequently disastrous consequences known as the Tropical Cyclone (TC). This is an intense cyclone, generated over a tropical ocean with kinetic energy 1018 J or more, which extends over several hundred kilometres and yet is above all characterized by its calm central region: ``the eye of the storm''. In a TC (not, of course, to be confused with such completely different phenomena as tornadoes) both the energy input and its dissipation mainly occur within that boundary layer between air and ocean which, at high TC wind speeds of 50-60 m/s, comprises essentially ``a third fluid'': ocean spray. Afterwards, as a TC reaches land, disastrous effects of several different kinds may occur, and this paper outlines how fluid mechanics contributes towards worldwide struggles to reduce the human impact of TC disasters.

  17. 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.

  18. Annual review of fluid mechanics, Volume 15

    NASA Astrophysics Data System (ADS)

    van Dyke, M.; Wehausen, J. V.; Lumley, J. L.

    A survey of experimental results and analytical techniques for modelling various flows and the behavior of flows around flown-driven machinery is presented. Attention is given to analytical models for wind flows and power extraction by horizontal axis wind turbines. The phenomena occurring in the impact of compressible fluids with a solid body are described, as are the instabilities, pattern formation, and turbulence in flames. Homogeneous turbulence is explored, theories for autorotation by falling bodies are discussed, and attention is devoted to theoretical models for magneto-atmospheric waves and their presence in solar activity. The design characteristics of low Reynolds number airfoils are explored, and numerical and fluid mechanics formulations for integrable, chaotic, and turbulent vortex motion in two-dimensional flows are reviewed. Finally, measurements and models of turbulent wall jets for engineering purposes are examined. (For individual items see A83-31077 to A83-31086)

  19. 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.

  20. 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.

  1. Fluid mechanics of artificial heart valves.

    PubMed

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

    2009-02-01

    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. 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 simulation studies have served to identify candidate compounds for use as reactive tracers. An emerging class of materials that show promise for use as geothermal and EGS tracers are colloidal nanocrystals (quantum dots). These are semiconductor particles that fluoresce as a function of particle size. Preliminary laboratory experimentation has demonstrated that these thermally stable, water-soluble particles can serve as conservative tracers for geothermal applications. Likewise, they show promise as potential reactive tracers, since their surfaces can be modified to be reversibly sorptive and their diameters are sufficiently large to allow for contrasts in diffusivity with solute tracers.

  3. 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.

  4. 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.

  5. 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).

  6. 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…

  7. 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.

  8. Job Prospects for Mechanical Engineers.

    ERIC Educational Resources Information Center

    Basta, Nicholas

    1986-01-01

    Discusses the career outlook for mechanical engineers. Explains that the number of bachelor degrees awarded yearly has reached a plateau, but salaries continue to rise. Suggests that the largest increase in demand for mechanical engineers will come from industries involved in automation, particularly those developing robotics. (TW)

  9. Job Prospects for Mechanical Engineers.

    ERIC Educational Resources Information Center

    Basta, Nicholas

    1985-01-01

    Indicates that the healthy economy is providing multiple opportunities for graduating mechanical engineers (including more job offers and higher pay) and that greatly expanded funding of military-defense work and computer applications are contributing to this growth. Data on mechanical engineering degrees granted, salaries, and industry growth are…

  10. 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

  11. 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…

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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)

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Fluid Mechanics of Blood Clot Formation

    PubMed Central

    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. PMID:26236058

  6. Hamiltonian mechanics limits microscopic engines

    NASA Astrophysics Data System (ADS)

    Anglin, James; Gilz, Lukas; Thesing, Eike

    2015-05-01

    We propose a definition of fully microscopic engines (micro-engines) in terms of pure mechanics, without reference to thermodynamics, equilibrium, or cycles imposed by external control, and without invoking ergodic theory. This definition is pragmatically based on the observation that what makes engines useful is energy transport across a large ratio of dynamical time scales. We then prove that classical and quantum mechanics set non-trivial limits-of different kinds-on how much of the energy that a micro-engine extracts from its fuel can be converted into work. Our results are not merely formal; they imply manageable design constraints on micro-engines. They also suggest the novel possibility that thermodynamics does not emerge from mechanics in macroscopic regimes, but rather represents the macroscopic limit of a generalized theory, valid on all scales, which governs the important phenomenon of energy transport across large time scale ratios. We propose experimental realizations of the dynamical mechanisms we identify, with trapped ions and in Bose-Einstein condensates (``motorized bright solitons'').

  7. 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.

  8. Fluid Mechanics of the ``Vortex Fluidic Device''

    NASA Astrophysics Data System (ADS)

    Dalziel, Stuart; Britton, Joshua; Raston, Colin

    2014-11-01

    The Vortex Fluidic Device (VFD) provides a new ``green'' alternative for many industrially important organic chemistry processes including the generation of biodiesel. Improved chemical kinetics have also been demonstrated for a number of reactions. This relatively simple device, comprising essentially of a rapidly rotating tube, provides advantages ranging from reduced energy requirements and waste streams to high flow rates and the avoidance of clogging. The VFD is effective due to the interplay between fluid mechanics and chemistry providing near optimal conditions for the required reactions. This contribution provides an insight into the rich fluid mechanics of the device.

  9. 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. PMID:26345121

  10. Nonholonomic Mechanics and Fluid-Body Interactions

    NASA Astrophysics Data System (ADS)

    Kelly, Scott; Tallapragada, Phanindra

    2012-11-01

    Certain velocity constraints arising in idealized models for fluid-body interactions, including the Kutta condition classically applied at the trailing cusp of a Joukowski hydrofoil experiencing lift, are formally equivalent to nonintegrable constraints arising in the mechanics of finite-dimensional mechanical systems. This equivalence allows hydrodynamic problems involving vortex shedding and related phenomena to be framed in the context of geometric mechanics on manifolds, and for essential mechanisms of biomorphic aquatic propulsion to be interpreted in terms of symmetry-breaking and generalized momentum equations. We illustrate this perspective using simple examples that highlight parallels between the finite- and infinite-dimensional cases.

  11. 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.

  12. Propulsion Mechanism of Catalytic Microjet Engines.

    PubMed

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

    2014-02-01

    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

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Fluid design studies of integrated modular engine system

    NASA Technical Reports Server (NTRS)

    Frankenfield, Bruce; Carek, Jerry

    1993-01-01

    A study was performed to develop a fluid system design and show the feasibility of constructing an integrated modular engine (IME) configuration, using an expander cycle engine. The primary design goal of the IME configuration was to improve the propulsion system reliability. The IME fluid system was designed as a single fault tolerant system, while minimizing the required fluid components. This study addresses the design of the high pressure manifolds, turbopumps and thrust chambers for the IME configuration. A physical layout drawing was made, which located each of the fluid system components, manifolds and thrust chambers. Finally, a comparison was made between the fluid system designs of an IME system and a non-network (clustered) engine system.

  6. 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 ...

  7. 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.

  8. 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.…

  9. 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

  10. 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…

  11. 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 ? and activity coefficient ?i) and ensemble average potential energy u for one molecule. The statistical mechanical expressions of separation factor ? and activity coefficient ?i 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 ?i 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 ? and activity coefficient ?i have good compatibility with classical thermodynamic equations and quantum mechanical COSMO-SAC approach.

  12. 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)

  13. 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. PMID:14561348

  14. 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

  15. Gray's paradox: A fluid mechanical perspective

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    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.

  16. Robust control problems in fluid mechanics

    NASA Astrophysics Data System (ADS)

    Tachim Medjo, T.

    2001-03-01

    In this paper, we study a class of robust control problems in fluid mechanics recently proposed by Bewley et al. [Physica D 138 (3-4) (2000) 360]. Using a method of Shutyaev [Russ. J. Numer. Anal. Math. Modell. 14 (2) (1999) 137], we provide another proof of the existence and the uniqueness of solutions to the robust control problems under weaker assumptions as compared to those of Bewley et al. [Physica D 138 (3-4) (2000) 360]. From the numerical point of view, the method used in this paper is particularly important since it provides a constructive way to approximate the solutions to these nonlinear control problems.

  17. The Fluid Mechanics of Carbon Dioxide Sequestration

    NASA Astrophysics Data System (ADS)

    Huppert, Herbert E.; Neufeld, Jerome A.

    2014-01-01

    Humans are faced with a potentially disastrous global problem owing to the current emission of 32 gigatonnes of carbon dioxide (CO2) annually into the atmosphere. A possible way to mitigate the effects is to store CO2 in large porous reservoirs within the Earth. Fluid mechanics plays a key role in determining both the feasibility and risks involved in this geological sequestration. We review current research efforts looking at the propagation of CO2 within the subsurface, the possible rates of leakage, the mechanisms that act to stably trap CO2, and the geomechanical response of the crust to large-scale CO2 injection. We conclude with an outline for future research.

  18. 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.

  19. 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.

  20. Quantification of fluid shear stress in bone tissue engineering scaffolds with spherical and cubical pore architectures.

    PubMed

    Zhao, Feihu; Vaughan, Ted J; McNamara, Laoise M

    2016-06-01

    Recent studies have shown that mechanical stimulation, in the form of fluid perfusion and mechanical compression, can enhance osteogenic differentiation of mesenchymal stem cells and bone cells within tissue engineering scaffolds in vitro. The precise nature of mechanical stimulation within tissue engineering scaffolds is not only dictated by the exogenously applied loading regime, but also depends on the geometric features of the scaffold, in particular architecture, pore size and porosity. However, the precise contribution of each geometric feature towards the resulting mechanical stimulation within a scaffold is difficult to characterise due to the wide range of interacting parameters. In this study, we have applied a fluid-structure interaction model to investigate the role of scaffold geometry (architecture, pore size and porosity) on pore wall shear stress (WSS) under a range of different loading scenarios: fluid perfusion, mechanical compression and a combination of perfusion and compression. It is found that scaffold geometry (spherical and cubical pores), in particular the pore size, has a significant influence on the stimulation within scaffolds. Furthermore, we observed an amplified WSS within scaffolds under a combination of fluid perfusion and mechanical compression, which exceeded that caused by individual fluid perfusion or mechanical compression approximately threefold. By conducting this comprehensive parametric variation study, an expression was generated to allow the design and optimisation of 3D TE scaffolds and inform experimental loading regimes so that a desired level of mechanical stimulation, in terms of WSS is generated within the scaffold. PMID:26224148

  1. 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).

  2. 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…

  3. 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 a hypothetical VIV energy harvesting device. By replacing standard linear springs with nonlinear ones, we can broaden the system's frequency response. Next, we transition from bluff bodies to unsteady airfoils, where we begin by measuring the thrust and efficiency of an airfoil pitching about its quarter-chord point. Finally, we examine how the propulsive performance of an oscillating airfoil is improved by the addition of passive dynamics.

  4. Teaching Technical Competencies for Fluid Mechanics Research

    NASA Astrophysics Data System (ADS)

    Tagg, Randall

    2014-11-01

    We are developing an ``on demand'' framework for students to learn techniques used in fluid mechanics research. The site for this work is a university-grade laboratory situated next to Gateway High School in Aurora, Colorado. Undergraduate university students work with K-12 students on research and technical innovation projects. Both groups need customized training as their projects proceed. A modular approach allows particular competencies such as pump selection, construction of flow piping and channels, flow visualization, and specific flow measurement methods to be acquired through focused lessons. These lessons can be learned in either a stand-alone fashion or assembled into units for formal courses. A research example was a student project on diffusion of infectious material in micro-gravity in the event of an intestinal puncture wound. A curriculum example is a 9-week quarter of high-school instruction on instrumentation that uses small-scale water treatment systems as a case study.

  5. 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

  6. 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…

  7. 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.

  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. PMID:26415215

  9. 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).

  10. 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).

  11. Defining the Australian Mechanical Engineer

    ERIC Educational Resources Information Center

    Ferguson, Clive

    2006-01-01

    The attribute focus in engineering education now adopted by the engineering education accrediting bodies of the US, UK and Australia is based on meeting the assumed needs of professional practice. It is associated with an increasing expectation by employers of work-ready graduates rather than relying on subsequent work-based learning and…

  12. Dictionary of mechanical engineering, third edition

    SciTech Connect

    Nayler, G.H.F.

    1985-01-01

    This dictionary provides coverage of terms currently used in mechanical and production engineering. Since the publication of the previous edition ten years ago many new terms have been added to the engineer's vocabulary, particularly in fields related to robotics, automation, and computer applications. This edition has been revised to cover a broader range of topics and contains many new illustrations and over 700 new entries. There are also appendices listing engineering symbols and abbreviations, and an extensive list of engineering organizations.

  13. Small Engine Mechanics. Post Secondary Curriculum Guide.

    ERIC Educational Resources Information Center

    Watkins, James F.; And Others

    This curriculum guide was designed for use in postsecondary small engine mechanics education programs in Georgia. Its purpose is to provide for the development of entry level skills in small engine mechanics in the areas of knowledge, theoretical structure, tool usage, diagnostic ability, related supportive skills, and occupational survival…

  14. 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…

  15. 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…

  16. 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 mechanics of cricket and tennis balls will be discussed in detail with the help of latest test data, analyses and video clips.

  17. 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

  18. 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…

  19. 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.

  20. Annual review of fluid mechanics. Volume 13

    NASA Astrophysics Data System (ADS)

    van Dyke, M.; Wehausen, J. V.; Lumley, J. L.

    The review includes papers on fluid-dynamical problems in galaxies, existence theorems for the equations of motion of a compressible viscous fluid, conditional sampling in turbulence measurement, power from water waves, and aspects of three-dimensional laminar boundary layers. Also, topics covered modeling of planetary boundary layers, cavitation in fluid machinery and hydraulic structures, cup, propeller, vane, and sonic anemometers in turbulence research, and organized motion in turbulent flow.

  1. Mechanical autonomous stochastic heat engines

    NASA Astrophysics Data System (ADS)

    Serra-Garcia, Marc; Foehr, Andre; Moleron, Miguel; Lydon, Joseph; Chong, Christopher; Daraio, Chiara; . Team

    Stochastic heat engines extract work from the Brownian motion of a set of particles out of equilibrium. So far, experimental demonstrations of stochastic heat engines have required extreme operating conditions or nonautonomous external control systems. In this talk, we will present a simple, purely classical, autonomous stochastic heat engine that uses the well-known tension induced nonlinearity in a string. Our engine operates between two heat baths out of equilibrium, and transfers energy from the hot bath to a work reservoir. This energy transfer occurs even if the work reservoir is at a higher temperature than the hot reservoir. The talk will cover a theoretical investigation and experimental results on a macroscopic setup subject to external noise excitations. This system presents an opportunity for the study of non equilibrium thermodynamics and is an interesting candidate for innovative energy conversion devices.

  2. 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.

  3. 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.

  4. Geological fluid mechanics models at various scales

    NASA Astrophysics Data System (ADS)

    Saar, Martin Oliver

    2003-06-01

    In this dissertation, I employ concepts from fluid mechanics to quantitatively investigate geological processes in hydrogeology and volcanology. These research topics are addressed by utilizing numerical and analytical models but also by conducting field and lab work. Percolation theory is of interest to a wide range of physical sciences and thus warrants research in itself. Therefore, I developed a computer code to study percolation thresholds of soft-core polyhedra. Results from this research are applied to study the onset of yield strength in crystal-melt suspensions such as magmas. Implications of yield strength development in suspensions, marking the transition from Newtonian to Bingham fluid, include the pahoehoe-'a'a transition and the occurrence of effusive versus explosive eruptions. I also study interactions between volcanic processes and groundwater as well as between groundwater and seismicity (hydroseismicity). In the former case, I develop numerical and analytical models of coupled groundwater and heat transfer. Here, perturbations from a linear temperature-depth profile are used to determine groundwater flow patterns and rates. For the hydroseismicity project I investigate if seasonal elevated levels of seismicity at Mt. Hood, Oregon, are triggered by groundwater recharge. Both hydroseismicity and hydrothermal springs occur on the southern flanks of Mt. Hood. This suggests that both phenomena are related while also providing a connection between the research projects involving groundwater, heat flow, and seismicity. Indeed, seismicity may be necessary to keep faults from clogging thus allowing for sustained activity of hydrothermal springs. Finally, I present research on hydrologically induced volcanism, where a process similar to the one suggested for hydroseismicity is invoked. Here, melting of glaciers, or draining of lakes, during interglacial periods reduce the confining pressure in the subsurface which may promote dike formation and result in increased rates of volcanism. In general, problems discussed in this dissertation involve interactions among processes that are traditionally associated with separate research disciplines. However, numerous problems in the geosciences require a multidisciplinary approach, as demonstrated here. In addition, employing several analytical and numerical methods, such as signal processing, inverse theory, computer modeling, and percolation theory, allows me to study such diverse processes in a quantitative way.

  5. Introductory Education for Mechanical Engineering by Exercise in Mechanical Disassembly

    NASA Astrophysics Data System (ADS)

    Matsui, Yoshio; Asakawa, Naoki; Iwamori, Satoru

    An introductory program “Exercise for engineers in mechanical disassembly” is an exercise that ten students of every team disassemble a motor scooter to the components and then assemble again to the initial form in 15 weeks. The purpose of this program is to introduce mechanical engineering by touching the real machine and learning how it is composed from various mechanical parts to the students at the early period after the entrance into the university. Additional short lectures by young teachers and a special lecture by a top engineer in the industry encourage the students to combine the actual machine and the mechanical engineering subjects. Furthermore, various educations such as group leader system, hazard prediction training, parts filing are included in this program. As a result, students recognize the importance of the mechanical engineering study and the way of group working.

  6. 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).

  7. Encyclopedia of fluid mechanics, vol. 7

    SciTech Connect

    Cheremisinoff, N.P.

    1988-01-01

    Covers rheology and flow dynamics of non-Newtonian fluids, providing treatment of practical rheology and industrial handling and processing of rheologically complex fluids. Addressees compressible flow dynamics and aerodynamic principles important to discrete flow phenomena and process apparatus design. Divided into three sections: flow dynamics and transport phenomena, slippage ad drag phenomena, and polymer rheology and processing. Includes 35 chapters, index, and references at end of each chapter.

  8. 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.

  9. Fluid overload in acute heart failure--re-distribution and other mechanisms beyond fluid accumulation.

    PubMed

    Cotter, Gad; Metra, Marco; Milo-Cotter, Olga; Dittrich, Howard C; Gheorghiade, Mihai

    2008-02-01

    Although fluid overload is one of the most prominent features of acute heart failure (AHF), its mechanism remains challenging, due to the lack of consistent data from prospective studies. Traditionally, fluid overload was thought to be mainly the result of either increased intake of fluid and salt or non-adherence with diuretic therapy. However, recent data showed little weight change before or during an AHF event suggesting that in many cases fluid overload is caused by other mechanisms such as fluid redistribution and neurohormonal or inflammatory activation. Redistribution may be the result of a combined vascular and cardiac process reducing capacitance in the venous system (and hence increasing preload) and increasing arterial stiffness and resistance (and hence afterload). When these vascular processes occur acutely and are superimposed on reduced cardiac function; fluid is redistributed to the lungs instigating pulmonary congestion. In this paper we elaborate on this possible pathophysiological mechanism and review its potential causes and amplifiers. PMID:18279771

  10. 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.

  11. Mechanical equivalent of quantum heat engines.

    PubMed

    Arnaud, Jacques; Chusseau, Laurent; Philippe, Fabrice

    2008-06-01

    Quantum heat engines employ as working agents multilevel systems instead of classical gases. We show that under some conditions quantum heat engines are equivalent to a series of reservoirs at different altitudes containing balls of various weights. A cycle consists of picking up at random a ball from one reservoir and carrying it to the next, thereby performing or absorbing some work. In particular, quantum heat engines, employing two-level atoms as working agents, are modeled by reservoirs containing balls of weight 0 or 1. The mechanical model helps us prove that the maximum efficiency of quantum heat engines is the Carnot efficiency. Heat pumps and negative temperatures are considered. PMID:18643212

  12. 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.

  13. 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.

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

    PubMed Central

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

    2010-01-01

    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 since 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 since 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. PMID:20374482

  15. 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)

  16. Annual review of numerical fluid mechanics and heat transfer. Volume 1

    SciTech Connect

    Chawla, T.C.

    1986-01-01

    This book describes applications of numerical methods in fluid mechanics and heat transfer. Topics covered include the following: high speed gas dynamics; turbulence; multiphase flows; rheology; meteorology; tribology; oceanography; hydrology; combustion; chemical processes; metallurgy; energy conversion; power; biomedicine; noise and acoustics; nuclear and fusion engineering; low-gravity space manufacturing processes; and arctic and cryogenic heat transfer.

  17. 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)

  18. 7th International Symposium on Applications of Laser Techniques to Fluid Mechanics, volume 1

    NASA Astrophysics Data System (ADS)

    1994-07-01

    The proceedings volumes 1 and 2 comprise the papers that were accepted for presentation at the Seventh International Symposium on Applications of Laser Techniques to Fluid Mechanics held at The Calouste Gulbenkian Foundation in Lisbon, during the period of July 11 to 14, 1994. The prime objective of this Seventh Symposium is to provide a forum for the presentation of the most advanced research on laser techniques for flow measurements, and reveal significant results to fluid mechanics. The applications of laser techniques to scientific and engineering fluid flow research is emphasized, but contributions to the theory and practice of laser methods are also considered where they facilitate new improved fluid mechanics research. Attention is focused on laser-Doppler anemometry, particle sizing and other methods for the measurement of velocity and scalars such as particle image velocimetry and laser induced fluorescence.

  19. 7th International Symposium on Applications of Laser Techniques to Fluid Mechanics, volume 2

    NASA Astrophysics Data System (ADS)

    1994-07-01

    The proceedings volumes 1 and 2 comprise the papers that were accepted for presentation at the Seventh International Symposium on Applications of Laser Techniques to Fluid Mechanics held at The Calouste Gulbenkian Foundation in Lisbon, during the period of July 11 to 14, 1994. The prime objective of this Seventh Symposium is to provide a forum for the presentation of the most advanced research on laser techniques for flow measurements, and reveal significant results to fluid mechanics. The applications of laser techniques to scientific and engineering fluid flow research is emphasized, but contributions to the theory and practice of laser methods are also considered where they facilitate new improved fluid mechanic research. Attention is focused on laser-Doppler anemometry, particle sizing and other methods for the measurement of velocity and scalars such as particle image velocimetry and laser induced fluorescence.

  20. 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.

  1. 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

  2. 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.

  3. Fundamental studies of fluid mechanics and stability in porous media

    SciTech Connect

    Homsy, G.M.

    1991-08-01

    This report summarizes accomplished and proposed work for the fundamental studies of fluid mechanics and stability in porous media. Topics discussed include: viscous fingering in miscible displacements; polymer flow interactions in free shear layers of viscoelastic fluids; effect of nonmonotonic viscosity profiles on the stability of miscible displacements in porous media; and references. (JL)

  4. Industrial and environmental applications of fluid mechanics 1994. FED Volume 186

    SciTech Connect

    Morrow, T.B.; Horii, K.; Elger, D.F.; Marshall, L.R.

    1994-12-31

    The forum objective is to promote discussion and interchange of current information on developing and state-of-the-art applications of fluid mechanics technology. The program is organized as a technical forum to encourage the presentation of new ideas, especially those which may be so innovative that a conservative review process might delay their dissemination to the fluids engineering community. This year, the forum also includes papers for a session on Phase Separation and Distribution. The forum book also contains the papers presented in the Forum on Fluid Mechanics in Large Industrial Boilers and Heat Exchangers. Applications are varied and include gas pipelines, filtration equipment, fish passage facilities, environmental transport of contaminants, tanker ships, combustors, internal combustion engines, nozzles, air conditioners, water treatment plants, boilers, and electrostatic precipitators. Most papers have been processed separately for inclusion on the data base.

  5. A fluid-mechanical sewing machine

    NASA Astrophysics Data System (ADS)

    Lister, John; Chiu-Webster, Sunny

    2004-11-01

    It is a breakfast-table experience that when a viscous fluid thread falls a sufficient height onto a stationary horizontal surface the thread is undergoes a coiling instability. We describe experimental observations of a viscous thread falling onto a steadily moving horizontal belt. Low (or zero) belt speeds produce coiling as expected. High belt speeds produce a steady thread, whose shape is well-predicted by theory for a stretching catenary with surface tension and inertia. Intermediate belt speeds show various modes of oscillation, which produce a variety of `stitching' patterns on the belt. The onset of oscillations is predicted theoretically.

  6. 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 engineers made impact. Through a basic understanding of the history of MEMS, the background physics and scaling in micromechanical systems, and an introduction to baseline MEMS processes, a mechanical engineer should be well on his way to Alice's wonderland in the ever-exciting playground of MEMS.

  7. 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.

  8. 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.

  9. 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)

  10. 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.

  11. 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....

  12. 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....

  13. 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....

  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. 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)…

  16. 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…

  17. 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…

  18. 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

  19. Analysis of the fluid mechanical sewing machine

    NASA Astrophysics Data System (ADS)

    Brun, Pierre-Thomas; Audoly, Basile; Ribe, Neil

    2012-02-01

    A thin thread of viscous fluid falling onto a moving belt generates a surprising variety of patterns, similar to the stitch patterns produced by a traditional sewing machine. By simulating the dynamics of the viscous thread numerically, we can reproduce these patterns and their bifurcations. The results lead us to propose a new classification of the stitch patterns within a unified framework, based on the Fourier spectra of the motion of the point of contact of the thread with the belt. The frequencies of the longitudinal and transverse components of the contact point motion are locked in most cases to simple ratios of the frequency ?c of steady coiling on a surface at rest (i.e., the limit of zero belt speed). In particular, the ``alternating loops'' pattern involves the first five multiples of ?c/3. The dynamics of the patterns can be described by matching the upper (linear) and the lower (non-linear) portions of the thread. Following this path we propose a toy model that successfully reproduces the observed transitions from the steady dragged configuration to sinusoidal meanders, alternating loops, and the translated coiling pattern as the belt speed is varied.

  20. 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

  1. 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…

  2. 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.

  3. 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.

  4. Space-time fluid mechanics computation of heart valve models

    NASA Astrophysics Data System (ADS)

    Takizawa, Kenji; Tezduyar, Tayfun E.; Buscher, Austin; Asada, Shohei

    2014-10-01

    Fluid mechanics computation of heart valves with an interface-tracking (moving-mesh) method was one of the classes of computations targeted in introducing the space-time (ST) interface tracking method with topology change (ST-TC). The ST-TC method is a new version of the Deforming-Spatial-Domain/Stabilized ST (DSD/SST) method. It can deal with an actual contact between solid surfaces in flow problems with moving interfaces, while still possessing the desirable features of interface-tracking methods, such as better resolution of the boundary layers. The DSD/SST method with effective mesh update can already handle moving-interface problems when the solid surfaces are in near contact or create near TC, if the "nearness" is sufficiently "near" for the purpose of solving the problem. That, however, is not the case in fluid mechanics of heart valves, as the solid surfaces need to be brought into an actual contact when the flow has to be completely blocked. Here we extend the ST-TC method to 3D fluid mechanics computation of heart valve models. We present computations for two models: an aortic valve with coronary arteries and a mechanical aortic valve. These computations demonstrate that the ST-TC method can bring interface-tracking accuracy to fluid mechanics of heart valves, and can do that with computational practicality.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Mechanism and synergism in epithelial fluid and electrolyte secretion.

    PubMed

    Hong, Jeong Hee; Park, Seonghee; Shcheynikov, Nikolay; Muallem, Shmuel

    2014-08-01

    A central function of epithelia is the control of the volume and electrolyte composition of bodily fluids through vectorial transport of electrolytes and the obligatory H2O. In exocrine glands, fluid and electrolyte secretion is carried out by both acinar and duct cells, with the portion of fluid secreted by each cell type varying among glands. All acinar cells secrete isotonic, plasma-like fluid, while the duct determines the final electrolyte composition of the fluid by absorbing most of the Cl(-) and secreting HCO3 (-). The key transporters mediating acinar fluid and electrolyte secretion are the basolateral Na(+)/K(+) /2Cl(-) cotransporter, the luminal Ca(2+)-activated Cl(-) channel ANO1 and basolateral and luminal Ca(2+)-activated K(+) channels. Ductal fluid and HCO3 (-) secretion are mediated by the basolateral membrane Na(+)-HCO3 (-) cotransporter NBCe1-B and the luminal membrane Cl(-)/HCO3 (-) exchanger slc26a6 and the Cl(-) channel CFTR. The function of the transporters is regulated by multiple inputs, which in the duct include major regulation by the WNK/SPAK pathway that inhibit secretion and the IRBIT/PP1 pathway that antagonize the effects of the WNK/SPAK pathway to both stimulate and coordinate the secretion. The function of these regulatory pathways in secretory glands acinar cells is yet to be examined. An important concept in biology is synergism among signaling pathways to generate the final physiological response that ensures regulation with high fidelity and guards against cell toxicity. While synergism is observed in all epithelial functions, the molecular mechanism mediating the synergism is not known. Recent work reveals a central role for IRBIT as a third messenger that integrates and synergizes the function of the Ca(2+) and cAMP signaling pathways in activation of epithelial fluid and electrolyte secretion. These concepts are discussed in this review using secretion by the pancreatic and salivary gland ducts as model systems. PMID:24240699

  11. Mechanism and Synergism in Epithelial Fluid and Electrolyte Secretion

    PubMed Central

    Hong, Jeong Hee; Park, Seonghee; Shcheynikov, Nikolay; Muallem, Shmuel

    2014-01-01

    A central function of epithelia is the control of the volume and electrolyte composition of bodily fluids through vectorial transport of electrolytes and the obligatory H2O. In exocrine glands fluid and electrolyte secretion is carried out by both acinar and duct cells, with the portion of fluid secreted by each cell type vary among glands. All acinar cells secrete isotonic, plasma-like fluid, while the duct determines the final electrolyte composition of the fluid by absorbing most of the Cl− and secreting HCO3−. The key transporters mediating acinar fluid and electrolyte secretion are the basolateral Na+/K+/2Cl− cotransporter, the luminal Ca2+-activated Cl− channel ANO1 and basolateral and luminal Ca2+-activated K+ channels. Ductal fluid and HCO3− secretion are mediated by the basolateral membrane Na+-HCO3− cotransporter NBCe1-B and the luminal membrane Cl−/HCO3− exchanger slc26a6 and the Cl− channel CFTR. The function of the transporters is regulated by multiple inputs, which in the duct include major regulation by the WNK/SPAK pathway that inhibit secretion and the IRBIT/PP1 pathway that antagonize the effects of the WNK/SPAK pathway to both stimulate and coordinate the secretion. The function of these regulatory pathways in secretory glands acinar cells is yet to be examined. An important concept in biology is synergism among signaling pathways to generate the final physiological response that ensures regulation with high fidelity and guards against cell toxicity. While synergism is observed in all epithelial functions, the molecular mechanism mediating the synergism is not known. Recent work reveals a central role for IRBIT as a third messenger that integrates and synergizes the function of the Ca2+ and cAMP signaling pathways in activation of epithelial fluid and electrolyte secretion. These concepts are discussed in this review using secretion by the pancreatic and salivary gland ducts as model systems. PMID:24240699

  12. 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.

  13. 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.

  14. 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.

  15. Computational fluid dynamic design of rocket engine pump components

    NASA Astrophysics Data System (ADS)

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

    1992-07-01

    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.

  16. 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.

  17. 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…

  18. 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.

  19. 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).

  20. Stanley Corrsin Award Talk: Fluid Mechanics of Fungi and Slime

    NASA Astrophysics Data System (ADS)

    Brenner, Michael

    2013-11-01

    There are interesting fluid mechanics problems everywhere, even in the most lowly and hidden corners of forest floors. Here I discuss some questions we have been working on in recent years involving fungi and slime. A critical issue for the ecology of fungi and slime is nutrient availability: nutrient sources are highly heterogeneous, and strategies are necessary to find food when it runs out. In the fungal phylum Ascomycota, spore dispersal is the primary mechanism for finding new food sources. The defining feature of this phylum is the ascus, a fluid filled sac from which spores are ejected, through a build up in osmotic pressure. We outline the (largely fluid mechanical) design constraints on this ejection strategy, and demonstrate how it provides strong constraints for the diverse morphologies of spores and asci found in nature. The core of the argument revisits a classical problem in elastohydrodynamic lubrication from a different perspective. A completely different strategy for finding new nutrient is found by slime molds and fungi that stretch out - as a single organism- over enormous areas (up to hectares) over forest floors. As a model problem we study the slime mold Physarum polycephalum, which forages with a large network of connected tubes on the forest floors. Localized regions in the network find nutrient sources and then pump the nutrients throughout the entire organism. We discuss fluid mechanical mechanisms for coordinating this transport, which generalize peristalsis to pumping in a heterogeneous network. We give a preliminary discussion to how physarum can detect a nutrient source and pump the nutrient throughout the organism.

  1. 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.

  2. Fluid Mechanics of Torch Appearance in Capillary Microplasma Jet

    NASA Astrophysics Data System (ADS)

    Choi, Jaegu; Matsuo, Keita; Yoshida, Hidekazu; Hosseini, S. Hamid R.; Namihira, Takao; Katsuki, Sunao; Akiyama, Hidenori

    2009-01-01

    Atmospheric-pressure microplasma jets with long and fine torches have recently been used in industrial and medical applications, such as local dental treatment, inner surface treatment of capillaries, stimuli of microorganisms, and local cleaning of semiconductor devices. The final torch appearance is greatly dependent on both the plasma between electrodes and the gas flow that is also dominated by the configuration of the nozzle. In this study, the mechanisms of torch appearance in a dc-driven capillary microplasma jet using atmospheric-pressure air have been investigated. Experimentally measured visible torch lengths are analyzed on the basis of fluid mechanics using a fluid simulation code. The time evolution of the plasma torch is visualized with a high-speed camera, and the length and propagation velocity of the torch are presented.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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. PMID:23233019

  10. 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.

  11. 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 COAST GUARD, DEPARTMENT OF HOMELAND SECURITY MERCHANT MARINE OFFICERS AND SEAMEN REQUIREMENTS FOR RATING ENDORSEMENTS Qualified Member of the Engine Department § 12.15-13 Deck engine mechanic. (a) An applicant for an endorsement as deck...

  12. 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.

  13. Renal and Vascular Mechanisms of Thiazolidinedione-Induced Fluid Retention

    PubMed Central

    Yang, Tianxin; Soodvilai, Sunhapas

    2008-01-01

    Thiazolidinediones (TZDs) are peroxisome proliferator-activated receptor subtype γ (PPARγ) activators that are clinically used as an insulin sensitizer for glycemic control in patients with type 2 diabetes. Additionally, TZDs exhibit novel anti-inflammatory, antioxidant, and antiproliferative properties, indicating therapeutic potential for a wide variety of diseases associated with diabetes and other conditions. The clinical applications of TZDs are limited by the common major side effect of fluid retention. A better understanding of the molecular mechanism of TZD-induced fluid retention is essential for the development of novel therapies with improved safety profiles. An important breakthrough in the field is the finding that the renal collecting duct is a major site for increased fluid reabsorption in response to rosiglitazone or pioglitazone. New evidence also indicates that increased vascular permeability in adipose tissues may contribute to edema formation and body weight gain. Future research should therefore be directed at achieving a better understanding of the detailed mechanisms of TZD-induced increases in renal sodium transport and in vascular permeability. PMID:18784848

  14. 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.

  15. 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.

  16. 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.

  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. 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.

  19. 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.

  20. 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)

  1. 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.

  2. 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…

  3. 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.

  4. 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.

  5. Communications: Mechanical Deformation of Dendrites by Fluid Flow

    NASA Technical Reports Server (NTRS)

    Pilling, J.; Hellawell, A.

    1996-01-01

    It is generally accepted that liquid agitation during alloy solidification assists in crystal multiplication, as in dendrite fragmentation and the detachment of side arms in the mushy region of a casting. Even without deliberate stirring by electromagnetic or mechanical means, there is often vigorous interdendritic fluid flow promoted by natural thermosolutal convection. In this analysis, we shall estimate the stress at the root of a secondary dendrite arm of aluminum arising from the action of a flow of molten metal past the dendrite arm.

  6. 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. PMID:20058187

  7. 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,

  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. 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. 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,…

  11. 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...

  12. 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. PMID:27091173

  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. 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.

  15. 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.

  16. 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.

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

    PubMed Central

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

    1993-01-01

    The mechanical behavior of the neutrophil plays an important role in both the microcirculation and the immune system. Several laboratories in the past have developed mechanical models to describe different aspects of neutrophil deformability. In this study, the passive mechanical properties of normal human neutrophils have been further characterized. The cellular mechanical properties were assessed by single cell micropipette aspiration at fixed aspiration pressures. A numerical simulation was developed to interpret the experiments in terms of cell mechanical properties based on the Newtonian liquid drop model (Yeung and Evans, Biophys. J., 56: 139-149, 1989). The cytoplasmic viscosity was determined as a function of the ratio of the initial cell size to the pipette radius, the cortical tension, aspiration pressure, and the whole cell aspiration time. The cortical tension of passive neutrophils was measured to be about 2.7 x 10(-5) N/m. The apparent viscosity of neutrophil cytoplasm was found to depend on aspiration pressure, and ranged from approximately 500 Pa.s at an aspiration pressure of 98 Pa (1.0 cm H2O) to approximately 50 Pa.s at 882 Pa (9.0 cm H2O) when tested with a 4.0-micron pipette. These data provide the first documentation that the neutrophil cytoplasm exhibits non-Newtonian behavior. To further characterize the non-Newtonian behavior of human neutrophils, a mean shear rate gamma m was estimated based on the numerical simulation. The apparent cytoplasmic viscosity appears to decrease as the mean shear rate increases. The dependence of cytoplasmic viscosity on the mean shear rate can be approximated as a power-law relationship described by mu = mu c(gamma m/gamma c)-b, where mu is the cytoplasmic viscosity, gamma m is the mean shear rate, mu c is the characteristic viscosity at characteristic shear rate gamma c, and b is a material coefficient. When gamma c was set to 1 s-1, the material coefficients for passive neutrophils were determined to be mu c = 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

  18. 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

  19. 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…

  20. The interior working mechanism and temperature characteristics of a fluid based micro-vibration isolator

    NASA Astrophysics Data System (ADS)

    Wang, Jie; Zhao, Shougen; Wu, Dafang; Jing, Xingjian

    2016-01-01

    Micro-vibration isolation is a hot topic in spacecraft vibration control, and fluid based vibration isolators alternatively provide a good and reliable solution to this challenging issue. In this paper, a novel fluid based micro-vibration isolator (FBMVI) is investigated. According to its inherent working principle and deformation pattern, the generation mechanisms of the damping and stiffness characteristics are derived, which are nonlinear functions of the environmental temperature. Then a lumped parameter model which is expressed by the physical design parameters (PDPs) is constructed, and the corresponding performance objective indices (POIs) are also obtained by applying the equivalence of mechanical impedance. Based on the finite element analysis of the internal damping component, a single variable method is further adopted to carry out the parametric study, and the influences of each PDP on the POIs are analyzed in details. Finally, experiments are conducted to identify the variation of fluid bulk modulus with the outside environmental temperature, and to validate the performance of the isolator under different temperature environments. The tested results show great consistence compared with the predicted tendencies of the parametric study. The results of this study can provide a very useful insight into and/or an important guidance for the design and application of this type of FBMVIs in engineering practice.

  1. Thread amplitudes and frequencies in a fluid mechanical `sewing machine'

    NASA Astrophysics Data System (ADS)

    Morris, Stephen W.; Dawes, J. H. P.; Lister, John; Dalziel, Stuart

    2006-11-01

    A viscous thread falling on a surface exhibits the famous rope- coiling effect, in which the thread buckles to form loops. If the surface is replaced by a belt moving at speed U, the rotational symmetry of the buckling instability is broken and a wealth of interesting states are observed (1). We experimentally studied this fluid mechanical `sewing machine' in a new, more precise apparatus. As U is reduced, the stretched thread bifurcates into a meandering state in which the thread displacements are only transverse to the motion of the belt. We measured the amplitudes A and frequency φ of the meandering close to the bifurcation. For small U, single- frequency meandering bifurcates to a two-frequency `figure 8' state, which contains a significant 2φ component and parallel as well as transverse displacements. This eventually reverts to single-frequency coiling at smaller U. More complex, highly hysteretic states with additional harmonics are observed for larger nozzle heights. We propose to understand this zoology in terms of the generic amplitude equations appropriate for resonant interactions between three oscillatory modes with frequencies φ, 2φ and 3φ. The form of the amplitude equations captures both the axisymmetry of the U=0 coiling state and the symmetry-breaking effects induced by the moving belt.(1) Chiu-Webster and Lister, J. Fluid Mech., in press.

  2. Fluid Mechanics of Biological Surfaces and their Technological Application

    NASA Astrophysics Data System (ADS)

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

    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.

  3. 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. PMID:10840802

  4. 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.

  5. Fluid mechanics of membrane-coated ceramic filters

    SciTech Connect

    Ahluwalia, R.K.; Geyer, H.K.

    1996-07-01

    Analytical models are formulated for evaluating the fluid mechanics of membrane-coated, dead-end ceramic filters. The models are applicable to forward flow as in the filtration mode and reverse flow as in the back-pulse cleaning mode. General criteria are derived to size the filter passages from considerations of Darcy pressure drop, friction pressure drop, and the dynamic head. These criteria together with Reynolds numbers are shown to provide measures of nonuniformities in face velocity and pressure that develop in the filter passages for atmospheric and high-pressure applications. A methodology is presented for optimizing the venturi geometry from the standpoint of minimizing pulse gas usage and controlling the thermal load imposed on the filter assembly.

  6. Fluid Mechanics of a High Performance Racing Bicycle Wheel

    NASA Astrophysics Data System (ADS)

    Mercat, Jean-Pierre; Cretoux, Brieuc; Huat, Francois-Xavier; Nordey, Benoit; Renaud, Maxime; Noca, Flavio

    2013-11-01

    In 2012, MAVIC released the most aerodynamic bicycle wheel on the market, the CXR 80. The french company MAVIC has been a world leader for many decades in the manufacturing of bicycle wheels for competitive events such as the Olympic Games and the Tour de France. Since 2010, MAVIC has been in a research partnership with the University of Applied Sciences in Geneva, Switzerland, for the aerodynamic development of bicycle wheels. While most of the development up to date has been performed in a classical wind tunnel, recent work has been conducted in an unusual setting, a hydrodynamic towing tank, in order to achieve low levels of turbulence and facilitate quantitative flow visualization (PIV). After a short introduction on the aerodynamics of bicycle wheels, preliminary fluid mechanics results based on this novel setup will be presented.

  7. 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.

  8. 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.

  9. 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.

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

    NASA Technical Reports Server (NTRS)

    Hersh, A. S.; Rogers, T.

    1975-01-01

    A fluid mechanical model of the acoustic behavior of small orifices is presented which predicts orifice impedance as a function of incident sound pressure level, frequency, and orifice geometry. Agreement between predicted and measured values (in both water and air) of orifice impedance is excellent. The model shows that (1) the acoustic flow in the immediate neighborhood of the orifice can be modelled as a locally spherical flow, (2) within this near field, the flow is, to a first approximation, unsteady and incompressible, and (3) 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 orifice neighborhood.-

  11. 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.

  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. Coarsening mechanisms of droplet spinodal decomposition in binary fluid mixtures

    NASA Astrophysics Data System (ADS)

    Tanaka, Hajime

    1996-12-01

    We demonstrate here the experimental results indicating the existence of interdroplet interactions between droplets even in the late stage of droplet spinodal decomposition. On the basis of these results, we discuss a few possible coarsening mechanisms of droplet spinodal decomposition. A droplet of finite curvature has long-range concentration fields around it to satisfy the boundary condition given by the Gibbs-Thomson relation. For a pair of neighboring droplets, thus, the closed isoconcentration lines including the two droplets are generally formed in the matrix phase in the late stage of spinodal decomposition. Thus, the droplet can feel its neighboring droplet via the concentration gradient produced by the latter. The excess bulk and gradient energy associated with the diffuse concentration changes around droplets may cause a long-range attractive interaction between the droplets, which induces the interdroplet collisions. We call this mechanism ``gradient-induced-coupling mechanism.'' The gradient force associated with an interface is likely responsible for the motion of droplets under the incompressibility condition. In fluid mixtures, this coupling of concentration fields can further be enhanced by the violation of the local equilibrium due to the quick hydrodynamic coalescence of colliding droplets. In such a case, there is a possibility that the concentration diffusion cannot follow this quick geometrical coarsening. This interface quench effect probably leads to the phenomenon of ``collision-induced collision via diffusion'': A droplet experiencing collision, which accompanies strong diffusion fields, has a higher probability of the subsequent collisions. The hydrodynamic flow induced by droplet coalescence also leads to the subsequent collisions, which we call ``collision-induced collision via flow.'' Further, the geometrical configuration of droplets also leads to ``geometrical collision-induced collision.'' All the above mechanisms likely make the coarsening of droplet spinodal decomposition faster than the prediction of Brownian-coagulation mechanism.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Engineering Biosynthesis Mechanisms for Diversifying Polyhydroxyalkanoates.

    PubMed

    Chen, Guo-Qiang; Hajnal, Ivan; Wu, Hong; Lv, Li; Ye, Jianwen

    2015-10-01

    Polyhydroxyalkanoates (PHA) are a family of diverse biopolyesters synthesized by bacteria. PHA diversity, as reflected by its monomers, homopolymers, random and block copolymers, as well as functional polymers, can now be generated by engineering the three basic synthesis pathways including the acetoacetyl-CoA pathway, in situ fatty acid synthesis, and/or β-oxidation cycles, as well as PHA synthase specificity. It is now possible to tailor the PHA structures via genome editing or process engineering. The increasing PHA diversity and maturing PHA production technology should lead to more focused research into their low-cost and/or high-value applications. PMID:26409776

  20. 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…

  1. 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…

  2. Superhydrophobic surface as a fluid enhancement material in engineering applications

    NASA Astrophysics Data System (ADS)

    Tetuko, Anggito P.; Khaerudini, Deni S.; Sardjono, Priyo; Sebayang, Perdamean; Rosengarten, Gary

    2013-09-01

    In this study, a superhydrophobic surface and its relation to the enhancement of the droplet fluid dynamics to the surface of the object materials was investigated. As the comparison, hydrophilic and uncoated surface of an object also investigated. The investigations used height of impact at 89 mm. The high quality speed camera is employed to investigate the droplet dynamic on a copper foil and a calcium fluoride surfaces. Both of the materials are coated with superhydrophobic and hydrophilic surfaces separately. The droplet diameter was analyzed using the program PHANTOM. The droplet contact angle was analyzed by the Goniometry method. The water was dropped on the calcium fluoride and the copper foil using a syringe (sharp tip) with initial droplet diameter of 1.9 mm. To record the droplet fluid shape, the photo micro sensor was placed inside the trigger box below the syringe. The results showed that the superhydrophobic surface both on copper foil and calcium fluoride enhanced the mobility of a droplet compared to the hydrophilic and the uncoated surfaces. The results showed that the maximum droplet diameter on the copper foil coated by the superhydrophobic, the hydrophilic and the uncoated surfaces are 4.7, 5.0, 5.2 mm, respectively; and for the calcium fluoride are 4.5, 5.1 and 5.5 mm, respectively. Meanwhile, the results for the droplet contact angle on the copper foil coated by the superhydrophobic, the hydrophilic and the uncoated surfaces are 20°, 90°, 160°, respectively; and for the calcium fluoride are 25°, 95°, 165°, respectively.

  3. Towards a statistical mechanical theory of active fluids.

    PubMed

    Marini Bettolo Marconi, Umberto; Maggi, Claudio

    2015-12-01

    We present a stochastic description of a model of N mutually interacting active particles in the presence of external fields and characterize its steady state behavior in the absence of currents. To reproduce the effects of the experimentally observed persistence of the trajectories of the active particles we consider a Gaussian force having a non-vanishing correlation time τ, whose finiteness is a measure of the activity of the system. With these ingredients we show that it is possible to develop a statistical mechanical approach similar to the one employed in the study of equilibrium liquids and to obtain the explicit form of the many-particle distribution function by means of the multidimensional unified colored noise approximation. Such a distribution plays a role analogous to the Gibbs distribution in equilibrium statistical mechanics and provides complete information about the microscopic state of the system. From here we develop a method to determine the one- and two-particle distribution functions in the spirit of the Born-Green-Yvon (BGY) equations of equilibrium statistical mechanics. The resulting equations which contain extra-correlations induced by the activity allow us to determine the stationary density profiles in the presence of external fields, the pair correlations and the pressure of active fluids. In the low density regime we obtained the effective pair potential ϕ(r) acting between two isolated particles separated by a distance, r, showing the existence of an effective attraction between them induced by activity. Based on these results, in the second half of the paper we propose a mean field theory as an approach simpler than the BGY hierarchy and use it to derive a van der Waals expression of the equation of state. PMID:26387914

  4. Healthcare Technology Management (HTM) of mechanical ventilators by clinical engineers.

    PubMed

    Yoshioka, Jun; Nakane, Masaki; Kawamae, Kaneyuki

    2014-01-01

    Mechanical ventilator failures expose patients to unacceptable risks, and maintaining mechanical ventilator safety is an important issue. We examined the usefulness of maintaining mechanical ventilators by clinical engineers (CEs) using a specialized calibrator. These evaluations and the ability to make in-house repairs proved useful for obviating the need to rent ventilators which, in turn, might prove faulty themselves. The CEs' involvement in maintaining mechanical ventilators is desirable, ensures prompt service, and, most importantly, enhances safe management of mechanical ventilators. PMID:25520839

  5. 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.

  6. Bayesian inverse problems for functions and applications to fluid mechanics

    NASA Astrophysics Data System (ADS)

    Cotter, S. L.; Dashti, M.; Robinson, J. C.; Stuart, A. M.

    2009-11-01

    In this paper we establish a mathematical framework for a range of inverse problems for functions, given a finite set of noisy observations. The problems are hence underdetermined and are often ill-posed. We study these problems from the viewpoint of Bayesian statistics, with the resulting posterior probability measure being defined on a space of functions. We develop an abstract framework for such problems which facilitates application of an infinite-dimensional version of Bayes theorem, leads to a well-posedness result for the posterior measure (continuity in a suitable probability metric with respect to changes in data), and also leads to a theory for the existence of maximizing the posterior probability (MAP) estimators for such Bayesian inverse problems on function space. A central idea underlying these results is that continuity properties and bounds on the forward model guide the choice of the prior measure for the inverse problem, leading to the desired results on well-posedness and MAP estimators; the PDE analysis and probability theory required are thus clearly dileneated, allowing a straightforward derivation of results. We show that the abstract theory applies to some concrete applications of interest by studying problems arising from data assimilation in fluid mechanics. The objective is to make inference about the underlying velocity field, on the basis of either Eulerian or Lagrangian observations. We study problems without model error, in which case the inference is on the initial condition, and problems with model error in which case the inference is on the initial condition and on the driving noise process or, equivalently, on the entire time-dependent velocity field. In order to undertake a relatively uncluttered mathematical analysis we consider the two-dimensional Navier-Stokes equation on a torus. The case of Eulerian observations—direct observations of the velocity field itself—is then a model for weather forecasting. The case of Lagrangian observations—observations of passive tracers advected by the flow—is then a model for data arising in oceanography. The methodology which we describe herein may be applied to many other inverse problems in which it is of interest to find, given observations, an infinite-dimensional object, such as the initial condition for a PDE. A similar approach might be adopted, for example, to determine an appropriate mathematical setting for the inverse problem of determining an unknown tensor arising in a constitutive law for a PDE, given observations of the solution. The paper is structured so that the abstract theory can be read independently of the particular problems in fluid mechanics which are subsequently studied by application of the theory.

  7. 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 processes in a variety of contexts. Our work has focused and will continue to focus on fluid mechanical phenomena that are of interest in energy-related technologies, with an emphasis on interfacial flows.

  8. Mechanisms of fluid production in smooth adhesive pads of insects

    PubMed Central

    Dirks, Jan-Henning; Federle, Walter

    2011-01-01

    Insect adhesion is mediated by thin fluid films secreted into the contact zone. As the amount of fluid affects adhesive forces, a control of secretion appears probable. Here, we quantify for the first time the rate of fluid secretion in adhesive pads of cockroaches and stick insects. The volume of footprints deposited during consecutive press-downs decreased exponentially and approached a non-zero steady state, demonstrating the presence of a storage volume. We estimated its size and the influx rate into it from a simple compartmental model. Influx was independent of step frequency. Fluid-depleted pads recovered maximal footprint volumes within 15 min. Pads in stationary contact accumulated fluid along the perimeter of the contact zone. The initial fluid build-up slowed down, suggesting that flow is driven by negative Laplace pressure. Freely climbing stick insects left hardly any traceable footprints, suggesting that they save secretion by minimizing contact area or by recovering fluid during detachment. However, even the highest fluid production rates observed incur only small biosynthesis costs, representing less than 1 per cent of the resting metabolic rate. Our results show that fluid secretion in insect wet adhesive systems relies on simple physical principles, allowing for passive control of fluid volume within the contact zone. PMID:21208970

  9. 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

  10. 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…

  11. Inhomogeneity of fluid flow in Stirling engine regenerators

    SciTech Connect

    Jones, J.D. )

    1989-10-01

    The literature relating to inhomogeneity of flow regenerators is briefly reviewed. It is noted that, in contrast to other applications of regenerators, relatively little attention has been paid to the consequences of flow inhomogeneity for thermal regeneration in Stirling cycle machines. The construction of regenerator capsules for a large stationary Stirling engine is described. A test rig is developed to measure the gas velocity profile across the face of the packed regenerator capsules under steady flow conditions. Measured flow profiles for a number of different matrix materials and construction techniques are presented, and it is noted that stacked-mesh regenerator matrices tend to display marked inhomogeneities of flow. The consequences of flow inhomogeneity for flow friction and regenerator effectiveness are analyzed theoretically, and approximate formulae deduced. One method for reducing flow inhomogeneity in stacked-screen matrice

  12. 19. VIEW OF ENGINE HOUSE INTERIOR, SHOWING CABLE MECHANISM (FLYWHEEL, ...

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

    19. VIEW OF ENGINE HOUSE INTERIOR, SHOWING CABLE MECHANISM (FLYWHEEL, GEAR, CABLE DRUM, LOCATOR DIAL), LOOKING EAST - Delaware, Lackawanna & Western Railroad, Pier No. 6, Erie Lackawanna Railroad Yard, Jersey City, Hudson County, NJ

  13. 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.

  14. 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

  15. 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 Garofalini (Rutgers), who has developed the best simulations of water ever reported by use of molecular dynamics. Simulated heating of water in small pores provided quantitative agreement with experiments, and showed that the origin of the high expansion is the altered structure of water in the first two molecular layers adjacent to the pore wall. The final focus of the project was to understand the damage done by crystals growing in small pores. For example, the primary cause of damage to ancient monuments in the Mediterranean Basin is growth of salt crystals in the pores of the stone. Salt may enter stone as a result of capillary rise of groundwater, by leaching of mortar joints, deposition of marine spray, or reactions with atmospheric pollutants (such as oxides of nitrogen or sulfur). As the water evaporates, the salt solution becomes supersaturated and crystals precipitate. Stress results, because the salt usually repels the minerals in the pore walls. Our goal was to identify the factors contributing to the repulsion, so that we could develop a chemical treatment to reduce the repulsion and hence the stress. (We have recently demonstrated an effective treatment as part of a separately funded study.) In collaboration with Prof. Garofalini, molecular dynamics simulations have been done that correctly reproduce the structure of water around dissolved ions of sodium and chloride. We simulated the interaction between crystals of sodium chloride and quartz, and found that this particular system exhibits attractive forces, in agreement with experiment. The origin of the attraction is the orientation of dipolar water molecules near the surfaces of the crystals. Similar calculations now must be done in systems, such as potassium chloride and quartz, where the interaction is repulsive. This grant supported the education of two doctoral students, Hang-Shing Ma (Ph.D., 2002) and Melanie Webb (Ph.D. expected 2010), three post-doctoral researchers, Joachim Gross, Gudrun Reichenauer, and Shuangyan (Sonia) Xu, and five undergraduates (for senior theses or independent projects), Shawn Ryan, Mary Yang, Matthew Gill, Lindsay Karfeld, and Greg Simmons.

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

    NASA Astrophysics Data System (ADS)

    Saviz, Camilla M.; Shakerin, Said

    2014-09-01

    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 coalescence. Including these toys in a class or lab with a companion exercise allows students to use observation and inductive reasoning to infer principles—all while having fun.

  17. 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. PMID:23892110

  18. The Fluid Dynamics of Solid Mechanical Shear Zones

    NASA Astrophysics Data System (ADS)

    Veveakis, E.; Regenauer-Lieb, K.

    2014-11-01

    Shear zones in outcrops and core drillings on active faults commonly reveal two scales of localization, with centimeter to tens of meters thick deformation zones embedding much narrower zones of mm-scale to cm-scale. The narrow zones are often attributed to some form of fast instability such as earthquakes or slow slip events. Surprisingly, the double localisation phenomenon seem to be independent of the mode of failure, as it is observed in brittle cataclastic fault zones as well as ductile mylonitic shear zones. In both, a very thin layer of chemically altered, ultra fine grained ultracataclasite or ultramylonite is noted. We present an extension to the classical solid mechanical theory where both length scales emerge as part of the same evolutionary process of shearing the host rock. We highlight the important role of any type of solid-fluid phase transitions that govern the second degree localisation process in the core of the shear zone. In both brittle and ductile shear zones, chemistry stops the localisation process caused by a multiphysics feedback loop leading to an unstable slip. The microstructural evolutionary processes govern the time-scale of the transition between slow background shear and fast, intermittent instabilities in the fault zone core. The fast cataclastic fragmentation processes are limiting the rates of forming the ultracataclasites in the brittle domain, while the slow dynamic recrystallisation prolongs the transition to ultramylonites into a slow slip instability in the ductile realm.

  19. Fluid Impact as a Source Mechanism for Surf Infrasound

    NASA Astrophysics Data System (ADS)

    Fee, D.; Garces, M.; McNamara, S.; Aucan, J.; Merrifield, M.

    2006-12-01

    The ability to provide infrasonic estimates of breaking ocean wave height and period in shallow reefs, steep rocky coastlines, and sand beaches has been demonstrated in previous work. Yet defining the source process and isolating the source pressure function remained elusive because of ambiguity introduced by complex coastlines and multiple breaker zones. Due to the steep bathymetry and its proximity to land, the Temae reef in the northeast coast of Moorea island, French Polynesia, provided a well constrained experimental environment where individual breaking waves could be identified and recorded. Synchronous wave height, infrasonic, seismic, and visual recordings of individual waves breaking against the shallow reef ledge were made and correlated. We characterize a possible fluid impact source mechanism for surf infrasound, demonstrate the capability to acoustically track alongshore traveling (peeling) plunging waves, and confirm a relationship between ocean wave height and infrasonic amplitude. Depending on the swell and coastal conditions, estimates of ocean wave period are also possible. We also present preliminary results on near-real-time remote infrasonic monitoring of the surf zone on the North Shore of Oahu, Hawaii, during the 2006-07 Winter high surf season.

  20. Slip, swim, mix, pack: Fluid mechanics at the micron scale

    NASA Astrophysics Data System (ADS)

    Lauga, Eric

    This thesis is devoted to fluid behavior at the micrometer length scale and considers four different problems. We first address the topic of the no-slip boundary condition in Newtonian liquids. After reviewing the field, we present models for apparent slip in three distinct experimental settings: Steady pressure-driven flow over heterogeneous surfaces, unsteady drainage flow over surface-attached bubbles, and flow of passive tracers affected by electrical forces. In all cases, we evaluate the apparent slip lengths and compare them to experimental results. We then propose a new method to probe slip, based on the influence of surface slip on the Brownian motion near a surface of a colloidal particle. We finish by showing that slip has virtually no influence on the non-modal stability of shear flows, despite its strong influence on unstable modes. The second problem we consider addresses mixing in micro-devices. We show that microchannels which are obtained with a single step of microfabrication (that is, have constant height) are able to generate fully three-dimensional flows, and could therefore be used as single-step passive micro-mixers. The third problem we present proposes a mechanical model for the motion of the bacterium E. coli near solid boundaries. It has been observed that, near a solid surface, E. coli does not swim in a straight line but in clockwise circles, which we show is a consequence of the hydrodynamic interactions between the free-swimming bacterium and the surface. The final problem we consider addresses self-assembly of micro-particles. We show that when spherical particles located on a liquid droplet are forced to come together by evaporation of the droplet, the geometrical and mechanical constraints arising during the process lead to unique final clusters. This allows us to propose a methodology to fabricate different clusters.

  1. 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…

  2. Fluid flow and fuel-air mixing in a motored two-dimensional Wankel rotary engine

    NASA Technical Reports Server (NTRS)

    Shih, T. I.-P.; Nguyen, H. L.; Stegeman, J.

    1986-01-01

    The implicit-factored method of Beam and Warming was employed to obtain numerical solutions to the conservation equations of mass, species, momentum, and energy to study the unsteady, multidimensional flow and mixing of fuel and air inside the combustion chambers of a two-dimensional Wankel rotary engine under motored conditions. The effects of the following engine design and operating parameters on fluid flow and fuel-air mixing during the intake and compression cycles were studied: engine speed, angle of gaseous fuel injection during compression cycle, and speed of the fuel leaving fuel injector.

  3. Fluid flow and fuel-air mixing in a motored two-dimensional Wankel rotary engine

    NASA Astrophysics Data System (ADS)

    Shih, T. I.-P.; Nguyen, H. L.; Stegeman, J.

    1986-06-01

    The implicit-factored method of Beam and Warming was employed to obtain numerical solutions to the conservation equations of mass, species, momentum, and energy to study the unsteady, multidimensional flow and mixing of fuel and air inside the combustion chambers of a two-dimensional Wankel rotary engine under motored conditions. The effects of the following engine design and operating parameters on fluid flow and fuel-air mixing during the intake and compression cycles were studied: engine speed, angle of gaseous fuel injection during compression cycle, and speed of the fuel leaving fuel injector.

  4. 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.

  5. Evolutionary mechanism as a template for protein engineering.

    PubMed

    Eisenbeis, Simone; Höcker, Birte

    2010-10-01

    The goal of a protein engineer is to adjust a protein to a specified new function. This is exactly what natural evolution has achieved many times. By studying evolutionary mechanisms, we can learn about ways to use the adaptability of proteins and to build new proteins. In fact, many techniques used in engineering are successfully mimicking evolutionary processes. We introduce the fundamental evolutionary mechanisms, take a closer look at duplication and fusion, recombination, and circular permutation and discuss their influence on protein engineering. Some important techniques are presented and illustrated with examples. PMID:20862721

  6. 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

  7. 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.

  8. Thermomechanical analysis of freezing-induced cell-fluid-matrix interactions in engineered tissues

    PubMed Central

    Han, Bumsoo; Teo, Ka Yaw; Ghosh, Soham; Dutton, J. Craig; Grinnell, Frederick

    2012-01-01

    Successful cryopreservation of functional engineered tissues (ETs) is significant to tissue engineering and regenerative medicine, but it is extremely challenging to develop a successful protocol because the effects of cryopreservation parameters on the post-thaw functionality of ETs are not well understood. Particularly, the effects on the microstructure of their extracellular matrix (ECM) have not been well studied, which determines many functional properties of the ETs. In this study, we investigated the effects of two key cryopreservation parameters – i) freezing temperature and corresponding cooling rate; and ii) the concentration of cryoprotective agent (CPA) on the ECM microstructure as well as the cellular viability. Using dermal equivalent as a model ET and DMSO as a model CPA, freezing-induced spatiotemporal deformation and post-thaw ECM microstructure of ETs was characterized while varying the freezing temperature and DMSO concentrations. The spatial distribution of cellular viability and the cellular actin cytoskeleton was also examined. The results showed that the tissue dilatation increased significantly with reduced freezing temperature (i.e., rapid freezing). A maximum limit of tissue deformation was observed for preservation of ECM microstructure, cell viability and cell-matrix adhesion. The dilatation decreased with the use of DMSO, and a freezing temperature dependent threshold concentration of DMSO was observed. The threshold DMSO concentration increased with lowering freezing temperature. In addition, an analysis was performed to delineate thermodynamic and mechanical components of freezing-induced tissue deformation. The results are discussed to establish a mechanistic understanding of freezing-induced cell-fluid-matrix interaction and phase change behavior within ETs in order to improve cryopreservation of ETs. PMID:23246556

  9. 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.

  10. 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…

  11. 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…

  12. 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

  13. 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…

  14. 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

  15. 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.

  16. Fundamental studies of fluid mechanics and stability in porous media

    SciTech Connect

    Homsy, G.M.

    1992-07-01

    We have been active in four areas: Numerical and analytical studies of viscous fingering in miscible displacements, including non- monotonic mobility profiles; numerical and analytical studies of the effect of non-Newtonian fluid characteristics on instabilities; experimental studies of instabilities of moving contact lines for Newtonian and non-Newtonian fluids; and studies of natural convective energy transport due to time-dependent body forces.

  17. High-pressure rocket engine turnaround duct computational fluid dynamics analysis

    NASA Astrophysics Data System (ADS)

    Cox, G. B., Jr.

    1984-10-01

    Current and projected high-pressure, staged-combustion rocket engine designs, such as the XLR129 and space shuttle main engine (SSME), introduced a type of turnaround duct flowpath wherein the turnaround is accompanied by an increase in mean radius and a decrease in fluid velocity through a subsequent diffuser. This turnaround duct flowpath is needed in the rocket engine to conduct high-pressure turbopump turbine discharge gases toward the main injector while maintaining a compact turbomachinery and powerhead flowpath. Current experience in the SSME shows that this type of turnaround duct can experience flow separation with an attendant increase in flow turbulence levels. Advances in computational fluid dynamics techniques over the last decade produced a number of codes which are applicable to the analysis and prediction of flow field behavior within such ducts. A version of the TEACH code developed at Pratt & Whitney Engineering Division was used to analyze three representative turnaround duct configurations. The study included the effects of fluid properties, inlet velocity flowfields, solution grid mesh size, and numerical solution algorithm upon calculated flow. Results include flow streamline comparisons, velocity profiles, and calculated total pressure losses. The results showed that turnaround ducts of the type studied can exhibit separation but that appropriately designed turnaround ducts can be made to function without suffering from internal flow separation.

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

    NASA Astrophysics Data System (ADS)

    Peng, Qing

    With the development of material science and technology, modification of substrates, which have random geometry and high aspect ratio three dimensional (3D) complex structures, with desired functional, reactive and stable coatings becomes important and challenging. The ability to fabricate mono- or multi-layers of functional materials with precisely controlled dimensions, finely tuned composition and molecular structures, attracts significant interests in materials science and is the key to construct such devices and structures at nano- and micro-scale with desired properties. In this study, supercritical carbon dioxide (scCO2) has been studied as an alternative route for modifying substrates due to the unique gas-like (low viscosity, high diffusivity and zero surface tension) and liquid-like properties (high density). (1) The reaction kinetics of metal oxides thin film deposition from pyrolysis of metal organics in scCO2 was studied in detail. This method was demonstrated as a powerful technique to coat oxides, including Al2O3, Ga2O3 and others, into 3D high aspect ratio complex structure of carbon nanotubes (CNTs) forest. (2) The low temperature scCO 2 based hydrogenolysis process was developed as a useful way to functionalize aligned CNTs forest with dense Nickel nanoparticles. On the second part of this work, atomic layer deposition (ALD)/molecular layer deposition (MLD), as a vapor phase, stepwise and self-limiting vacuum based deposition process, was demonstrated as a powerful way to form highly conformal and uniform film onto substrates, even into highly complex 3D complex structures. In this study, (4) Metal oxide ALD is applied onto 3D electrospun polymer microfiber mats template to illustrate an effective and robust strategy to fabricate long and uniform metal oxide microtubes with precisely controllable wall thickness. Designer tubes of various sizes and different materials were demonstrated by using this method. (5) By further extending this technique, 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.

  19. 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. PMID:14555440

  20. Coupled fluid and solid mechanics study for improved permeability estimation of fines' invaded porous materials

    NASA Astrophysics Data System (ADS)

    Mirabolghasemi, M.; Prodanovic, M.

    2012-12-01

    The problem of fine particle infiltration is seen in fields from subsurface transport, to drug delivery to industrial slurry flows. Sediment filtration and pathogen retention are well-known subsurface engineering problems that have been extensively studied through different macroscopic, microscopic and experimental modeling techniques Due to heterogeneity, standard constitutive relationships and models yield poor predictions for flow (e.g. permeability) and rock properties (e.g. elastic moduli) of the invaded (damaged) porous media. This severely reduces our ability to, for instance, predict retention, pressure build-up, newly formed flow pathways or porous medium mechanical behavior. We chose a coupled computational fluid dynamics (CFD) - discrete element modeling (DEM) approach to simulate the particulate flow through porous media represented by sphere packings. In order to minimize the uncertainty involved in estimating the flow properties of porous media on Darcy scale and address the dynamic nature of filtration process, this microscopic approach is adapted as a robust method that can incorporate particle interaction physics as well as the heterogeneity of the porous medium.. The coupled simulation was done in open-source packages which has both CFD (openFOAM) and DEM components (LIGGGHTS). We ran several sensitivity analyses over different parameters such as particle/grain size ratio, fluid viscosity, flow rate and sphere packing porosity in order to investigate their effects on the depth of invasion and damaged porous medium permeability. The response of the system to the variation of different parameters is reflected through different clogging mechanism; for instance, bridging is the dominant mechanism of pore-throat clogging when larger particles penetrate into the packing, whereas, in case of fine particles which are much smaller than porous medium grains (1/20 in diameter), this mechanism is not very effective due to the frequent formation and destruction of particle bridges. Finally, depending on the material and fluids that penetrate into the porous medium, the ionic forces might play a significant role in the filtration process. We thus also report on influence of particle attachment (and detachment) on the type of clogging mechanisms. Pore scale simulations allow for visualization and understanding of fundamental processes, and, further, the velocity fields are integrated into a distinctly non-monotonic permeability-porosity/(depth of penetration) relationship.

  1. 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.

  2. 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

  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. 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.

  5. AN OVERVIEW OF THE SNS ACCELERATOR MECHANICAL ENGINEERING.

    SciTech Connect

    HSEUH, H.; LUDWIG, H.; MAHLER, G.; PAI, C.; PEARSON, C.; RANK, J.; TUOZZOLO, J.; WEI, J.

    2006-06-23

    The Spallation Neutron Source (SNS*) is an accelerator-based neutron source currently nearing completion at Oak Ridge National Laboratory. When completed in 2006, the SNS will provide a 1 GeV, 1.44 MW proton beam to a liquid mercury target for neutron production. SNS is a collaborative effort between six U.S. Department of Energy national laboratories and offered a unique opportunity for the mechanical engineers to work with their peers from across the country. This paper presents an overview of the overall success of the collaboration concentrating on the accelerator ring mechanical engineering along with some discussion regarding the relative merits of such a collaborative approach. Also presented are a status of the mechanical engineering installation and a review of the associated installation costs.

  6. 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.

  7. Gas residues of engine starting fluid in postmortem sample from an arsonist.

    PubMed

    Schuberth, J

    1997-01-01

    Diethyl ether was found in samples of the blood, urine, and lung from a fire victim. Because the lung also carried a number of low-boiling paraffins, it was inferred that the detected compounds came from engine starting fluid, which the victim apparently had been exposed to while be intentionally used it as an accelerant to start the fire. The reported death illustrates the value of searching post mortem samples for highly volatile residues of possible arson accelerants. PMID:8988590

  8. Mechanical engineers' handbook, energy and power. 3rd ed.

    SciTech Connect

    Myer Kutz

    2005-12-15

    In addition to chapters on thermophysical properties of fluids, fundamentals of fluid mechanics, thermodynamics, heat transfer, combustion, and furnaces, Book 4 of the Handbook features coverage of both conventional (gaseous and liquid fuels, coal, and nuclear) and alternative (solar, geothermal, and fuel cells) energy sources, plus chapters on power machinery, refrigeration and cryogenics, environmental issues, and thermal systems optimization. Much of the material in this book is new or extensively revised, including coverage of such topics as: Heat pipes; Wind turbines; Fuel cells; Thermal systems optimization; Combustion; Fans, blowers, compressors, and pumps; Indoor environmental control; and Fluid power. Chapters of particular interest are: Combustion by Eric Eddings; Furnaces by Carroll Cone; Gaseous fuels by Richard J. Reed; Coals, lignite, peat by James Keppeler; and Air pollution-control technologies by C.A. Miller.

  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. 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...

  11. 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...

  12. 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...

  13. 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...

  14. 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.

  15. 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 can ensure its low cost and high quality for development.

  16. Thermal/Fluid Analysis of a Composite Heat Exchanger for Use on the RLV Rocket Engine

    NASA Technical Reports Server (NTRS)

    Nguyen, Dalton; Turner, Larry D. (Technical Monitor)

    2001-01-01

    As part of efforts to design a regeneratively cooled composite nozzle ramp for use on the reusable vehicle (RLV) rocket engine, a C-SiC composite heat exchanger concept was proposed for thermal performance evaluation. To test the feasibility of the concept, sample heat exchanger panels were made to fit the Glenn Research Center's cell 22 for testing. Operation of the heat exchanger was demonstrated in a combustion environment with high heat fluxes similar to the RLV Aerospike Ramp. Test measurements were reviewed and found to be valuable for the on-going fluid and thermal analysis of the actual RLV composite ramp. Since the cooling fluid for the heat exchanger is water while the RLV Ramp cooling fluid is LH2, fluid and therma models were constructed to correlate to the specific test set-up. The knowledge gained from this work will be helpful for analyzing the thermal response of the actual RLV Composite Ramp. The coolant thermal properties for the models are taken from test data. The heat exchanger's cooling performance was analyzed using the Generalized Fluid System Simulation Program (GFSSP). Temperatures of the heat exchanger's structure were predicted in finite element models using Patran and Sinda. Results from the analytical models and the tests show that RSC's heat exchanger satisfied the combustion environments in a series of 16 tests.

  17. Thermal/Fluid Analysis of a Composite Heat Exchanger for Use on the RLV Rocket Engine

    NASA Technical Reports Server (NTRS)

    Nguyen, Dalton

    2002-01-01

    As part of efforts to design a regeneratively cooled composite nozzle ramp for use on the reusable vehicle (RLV) rocket engine, an C-SiC composites heat exchanger concept was proposed for thermal performance evaluation. To test the feasibility of the concept, sample heat exchanger panels were made to fit the Glenn Research Center's cell 22 for testing. Operation of the heat exchanger was demonstrated in a combustion environment with high heat fluxes similar to the RLV Aerospike Ramp. Test measurements were reviewed and found to be valuable for the on going fluid and thermal analysis of the actual RLV composite ramp. Since the cooling fluid for the heat exchanger is water while the RLV Ramp cooling fluid is LH2, fluid and thermal models were constructed to correlate to the specific test set-up. The knowledge gained from this work will be helpful for analyzing the thermal response of the actual RLV Composite Ramp. The coolant thermal properties for the models are taken from test data. The heat exchanger's cooling performance was analyzed using the Generalized Fluid System Simulation Program (GFSSP). Temperatures of the heat exchanger's structure were predicted in finite element models using Patran and Sinda. Results from the analytical models and the tests show that RSC's heat exchanger satisfied the combustion environments in a series of 16 tests.

  18. 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.

  19. Mechanized fluid connector and assembly tool system with ball detents

    NASA Technical Reports Server (NTRS)

    Zentner, Ronald C. (Inventor); Smith, Steven A. (Inventor)

    1991-01-01

    A fluid connector system is disclosed which includes a modified plumbing union having a rotatable member for drawing said union into a fluid tight condition. A drive tool is electric motor actuated and includes a reduction gear train providing an output gear engaging an integral peripheral spur gear on the rotatable member. Coaxial alignment means are attached to both the connector assembly and the drive tool. A hand lever actuated latching system includes a plurality of circumferentially spaced latching balls selectively wedged against the alignment means attached to the connector assembly or to secure the drive tool with its output gear in mesh with the integral peripheral spur gear. The drive motor is torque, speed, and direction controllable.

  20. 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.

  1. 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.

  2. 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.

  3. Statistical mechanics of viscous flow in nematic fluids

    NASA Astrophysics Data System (ADS)

    Sarman, Sten; Evans, Denis J.

    1993-12-01

    We derive Green-Kubo (GK) relations for the viscosity coefficients of nematic liquid crystals. These GK relations are similar to, but considerably more complicated than, those of an isotropic fluid. In addition to shear viscosities there are also twist viscosities and cross couplings between the symmetric strain rate and the antisymmetric pressure tensor and vice versa. We show that the twist viscosity is inversely proportional to the mean square displacement of the director. Using the so-called SLLOD equations of motion we construct nonequilibrium molecular dynamics (NEMD) algorithms that can be used to efficiently calculate the viscosity coefficients of nematic liquid crystals from atomistic computer simulations. We also devise an additional NEMD algorithm for controlling the angular velocity of the director in a nematic fluid. We derive a fluctuation relation for the alignment angle between the director and the streamlines in planar Couette flow and also for the shear induced molecular angular velocity. In an isotropic fluid, close to equilibrium, this angular velocity is equal to half the vorticity. In a nematic liquid crystal it is nearly zero because of cross couplings with the symmetric part of the strain rate tensor. We test the Green-Kubo relations and the NEMD algorithms in a nematic liquid crystal modeled using a modified version of the Gay-Berne potential. In general, the Green-Kubo and NEMD results agree very well.

  4. Fluid Mechanics of the Vascular Basement Membrane in the Brain

    NASA Astrophysics Data System (ADS)

    Coloma, Mikhail; Hui, Jonathan; Chiarot, Paul; Huang, Peter; Carare, Roxana; McLeod, Kenneth; Schaffer, David

    2013-11-01

    Beta-amyloid is a normal product of brain metabolic function and is found within the interstitial fluid of the brain. Failure of the clearance of beta-amyloid from the aging brain leads to its accumulation within the walls of arteries and to Alzheimer's disease. The vascular basement membrane (VBM) within the walls of cerebral arteries surrounds the spirally arranged smooth muscle cells and represents an essential pathway for removal of beta-amyloid from the brain. This process fails with the stiffening of arterial walls associated with aging. In this study we hypothesize that the deformation of the VBM associated with arterial pulsations drives the interstitial fluid to drain in the direction opposite of the arterial blood flow. This hypothesis is theoretically investigated by modeling the VBM as a thin, coaxial, fluid-filled porous medium surrounding a periodically deforming cylindrical tube. Flow and boundary conditions required to achieve such a backward clearance are derived through a control volume analysis of mass, momentum, and energy.

  5. Statistical mechanics of a quenched van der Waals fluid

    NASA Astrophysics Data System (ADS)

    Singh, Rajiv R.; Kovac, Jeffrey

    1989-06-01

    The equilibrium properties of a quenched one-dimensional fluid with a high density phase transition are calculated using the formalism of Mazo in which the free energy is first calculated as a function of a certain quenched parameter and the quenched free energy is evaluated by averaging over the probability that the constraint is realized in the quenching process. The model system studied here is one in which the particles interact through a pair potential with a shoulder in the repulsive wall. The quenched parameter is taken to be the width of the shoulder, corresponding to the introduction of disorder or free volume into the quenched phase. Assuming a Gaussian distribution of shoulder widths it is possible to calculate the quenched free energy exactly and compare the thermodynamic properties of the quenched fluid to those of the equilibrium fluid. The quenched disorder softens the first-order freezing transition into a second-order-like glass transition which qualitatively reproduces the quasiequilibrium properties of real glasses.

  6. Power enhancement of heat engines via correlated thermalization in a three-level "working fluid".

    PubMed

    Gelbwaser-Klimovsky, David; Niedenzu, Wolfgang; Brumer, Paul; Kurizki, Gershon

    2015-01-01

    We explore means of maximizing the power output of a heat engine based on a periodically-driven quantum system that is constantly coupled to hot and cold baths. It is shown that the maximal power output of such a heat engine whose "working fluid" is a degenerate V-type three-level system is that generated by two independent two-level systems. Hence, level degeneracy is a thermodynamic resource that may effectively double the power output. The efficiency, however, is not affected. We find that coherence is not an essential asset in such multilevel-based heat engines. The existence of two thermalization pathways sharing a common ground state suffices for power enhancement. PMID:26394838

  7. Power enhancement of heat engines via correlated thermalization in a three-level working fluid

    NASA Astrophysics Data System (ADS)

    Gelbwaser-Klimovsky, David; Niedenzu, Wolfgang; Brumer, Paul; Kurizki, Gershon

    2015-09-01

    We explore means of maximizing the power output of a heat engine based on a periodically-driven quantum system that is constantly coupled to hot and cold baths. It is shown that the maximal power output of such a heat engine whose working fluid is a degenerate V-type three-level system is that generated by two independent two-level systems. Hence, level degeneracy is a thermodynamic resource that may effectively double the power output. The efficiency, however, is not affected. We find that coherence is not an essential asset in such multilevel-based heat engines. The existence of two thermalization pathways sharing a common ground state suffices for power enhancement.

  8. Wentworth Institute Resource Guide for Mechanical Engineering Laboratory Manual.

    ERIC Educational Resources Information Center

    Avakian, Harry; And Others

    This publication is a resource guide designed primarly as an aid to the instructor. All of the experiments contained in the Mechanical Engineering Laboratory Manual have been successfully completed under laboratory conditions by both staff and students. The results of these experiments have been computed and are presented in this publication. The…

  9. 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…

  10. 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…

  11. 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

  12. 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…

  13. 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.

  14. 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,

  15. 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,…

  16. Fundamental studies of fluid mechanics and stability in porous media. Progress report

    SciTech Connect

    Homsy, G.M.

    1991-08-01

    This report summarizes accomplished and proposed work for the fundamental studies of fluid mechanics and stability in porous media. Topics discussed include: viscous fingering in miscible displacements; polymer flow interactions in free shear layers of viscoelastic fluids; effect of nonmonotonic viscosity profiles on the stability of miscible displacements in porous media; and references. (JL)

  17. The research of the conductive mechanism and properties of magnetorheological fluids

    NASA Astrophysics Data System (ADS)

    Chen, Xi; Zhu, Xiaoqiang; Xu, Zeyu; Lin, Yuanchang; He, Guotian

    2013-06-01

    We investigated the resistance response induced by the magnetic field in magnetorheological fluids, the resulting magnetization process alters the distribution of the ferromagnetic particles from unordered distribution to catenulate distribution. Consequently the electrical conductive property of the whole sample changes. A four-stage model has been built to describe the distinct characteristics of the variation of the magnetorheological fluids resistance with a sectional formalism, which is found in excellent agreement with the experimental results. Also, the application of the electrical properties of the magnetorheological fluids in the engineering field is discussed.

  18. 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)

  19. 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 fluid systems, which are featured by fast rotation and very small viscosity effects, three dimensional fully nonlinear numerical simulations of Navier-Stokes equations play important roles. A precession-driven flow in a rotating channel is studied by the combination of asymptotic analysis and fully parallel numerical simulations. Various results of laminar and turbulent flows are thereby presented. Resonant precession-driven flows prove to be a possible candidate to persistently maintain the dynamo processes in the Earth-like planets. Computational fluid dynamics requires massive computing capability. Incompressibility and thin viscous boundary layers can pose huge difficulties to large scale numerical simulations. To make full use of the power of modern high performance computing facilities, a C++ 3D finite-element analysis code is under development based on PETSc platform. The code and data structures will be elaborated, along with the presentations of some preliminary calculations of the Jupiter's polytropic interior.

  20. Mechanical Role of Fluids in Earthquakes and Faulting

    NASA Astrophysics Data System (ADS)

    Rice, J. R.

    2005-12-01

    Following the contributions of Hubbert and Rubey, the level of ambient pore pressure is of accepted importance for understanding the static frictional strength of faults. There are also important dynamical interactions between pore fluids and faulting. Some of those are addressed here, with examples to be chosen from the following: (1) Pore fluid presence at full saturation promotes strong localization in rapidly shearing granular materials, even in cases for which the friction coefficient increases rapidly with shearing rate [see Rice, Rudnicki and Tsai, this meeting]. (2) Thermal pressurization of earthquake faults during seismic slip may provide the primary weakening process during earthquakes in mature crustal fault zones; it provides a plausible basic explanation, based on geological and laboratory data, of the magnitudes of the fracture energies of earthquakes as inferred independently from seismological data [see web link below]. The process also seems to be active in some large landslides. (3) Pore pressure alterations are induced by rapid mode II slip on fault planes when they have bordering gouge or damage zones which are of dissimilar permeability and/or poroelastic properties. This provides a fuller, new perspective on effects of material dissimilarity across a slip surface on altering the effective normal stress and thus interacting with dynamic rupture [see Rudnicki and Rice, this meeting]. (4) Gouge dilatancy associated with slip-rate increases induces suction in the pore fluid, so as to partially stabilize faults against earthquake nucleation, and also to slow rupture propagation into shallow fault regions. An open question is that of when and if shear heating acts to aid nucleation; the effect seems negligible for nucleation under slow tectonic loading but may be important for nucleation driven by sudden steps in stress. (5) Permeability determines pore pressure gradients for given flow rates, but increases in pore pressure cause increases in permeability. That allows slow solitary waves of pore pressure increase which propagate upwards against gravity in fault zones that are reasonably sealed from their surroundings, following initiation by, e.g., breaching of a pressurized seal at depth. (6) Aseismic slip transients in subduction zones occur in an environment of active compaction and metamorphic fluid release, and fluids seem responsible for associated tremor as well. Recent modeling [see Liu and Rice, this meeting] links elevation of fluid pressure to the speed of along-strike propagation of slip transients. (7) Poroelastic responses to stress transfer have been detected for some earthquakes, and associated transient stress changes may play a role in aftershock sequences, although probably secondary in general. (8) Another type of fluid saturated ``fault zone'', in granulated sediments between dissimilar materials, is the bed of a mobile ice sheet. Some of the concepts in topics 1 to 4 above may have application to surges, ice streams, and glacial earthquakes. These various cases 1 to 8 involve many contributors in the geophysical community, and include collaborative current or recent studies of the author with Massimo Cocco (2), Yajing Liu (4, 6), Alan Rempel (2), John Rudnicki (1,3), Paul Segall (4), and Victor Tsai (1,8).

  1. 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. PMID:26592438

  2. Molecular Mechanism of Pancreatic and Salivary Glands Fluid and HCO3− Secretion

    PubMed Central

    Lee, Min Goo; Ohana, Ehud; Park, Hyun Woo; Yang, Dongki; Muallem, Shmuel

    2013-01-01

    Fluid and HCO3− secretion is a vital function of all epithelia and is required for the survival of the tissue. Aberrant fluid and HCO3− secretion is associated with many epithelial diseases, such as cystic fibrosis, pancreatitis, Sjögren’s syndrome and other epithelial inflammatory and autoimmune diseases. Significant progress has been made over the last 20 years in our understanding of epithelial fluid and HCO3− secretion, in particular by secretory glands. Fluid and HCO3− secretion by secretory glands is a two step process. Acinar cells secrete isotonic fluid in which the major salt is NaCl. Subsequently, the duct modifies the volume and electrolyte composition of the fluid to absorb the Cl− and secrete HCO3−. The relative volume secreted by acinar and duct cells and modification of electrolyte composition of the secreted fluids varies among secretory glands to meet their physiological functions. In the pancreas, acinar cells secrete small amount of NaCl-rich fluid, while the duct absorbs the Cl− and secretes HCO3− and the bulk of the fluid in the pancreatic juice. Fluid secretion appears to be driven by active HCO3− secretion. In the salivary glands, acinar cells secrete the bulk of the fluid in the saliva that contains high concentrations of Na+ and Cl− and fluid secretion is mediated by active Cl− secretion. The salivary glands duct absorbs both the Na+ and Cl− and secretes K+ and HCO3−. In this review, we focus on the molecular mechanism of fluid and HCO3− secretion by the pancreas and salivary glands, to highlight the similarities of the fundamental mechanisms of acinar and duct cell functions, and point the differences to meet glands specific secretions. PMID:22298651

  3. 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. PMID:23660249

  4. 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 ...

  5. Method for starting and operating an advanced regenerative parallel compound dual fluid heat engine-advanced Cheng cycle(ACC)

    SciTech Connect

    Cheng, D.Y.

    1993-08-10

    In a Cheng cycle, dual fluid heat engine of the type is described having: (i) a gas turbine engine including a compressor for compressing a first working fluid, having a compressor outlet, a combustion chamber in fluid communication with the compressor outlet, a turbine unit having an inlet in fluid communication with the combustion chamber for performing work by expansion of working fluid, and a turbine exhaust; (ii) a heat recovery steam generator coupled to the turbine exhaust for heating a second working fluid having a superheater with an outlet and an inlet, an evaporator having an outlet coupled to the superheater inlet and an evaporator inlet, a heat recovery boiler between the evaporator inlet and outlet having a drum; (iii) an injector for introducing heated second working fluid from the heat recovery steam generator into the gas turbine; (iv) a coolant inlet port for introducing coolant to at least one of turbine nozzles and blades in the gas turbine; and (v) control valve means for selectively throttling flow rate of second working fluid into the gas turbine connected upstream of the injector; (vi) a compressed gas source and pressure regulator selectively in communication with the drum; (vii) a sensor system coupled to gas turbine engine and the heat recovery steam generator for temperature and pressure detection; and (viii) a control system for operating fuel flow to the gas turbine; a method of operation of the heat engine comprising: (a) initializing start conditions in the gas turbine engine and the heat recovery steam generator with the control system; (b) setting the control valve means for idle flow condition of the heat engine; (c) pressurizing the drum with the compressed gas source, (d) starting the gas turbine engine from idle to full load; (e) throttling second working fluid flow rate with the control valve means and shutting off the compressed gas source.

  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. 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.

  8. 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. PMID:26362920

  9. 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.

  10. 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.

  11. 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.

  12. A triphasic constrained mixture model of engineered tissue formation under in vitro dynamic mechanical conditioning.

    PubMed

    Soares, Joao S; Sacks, Michael S

    2016-04-01

    While it has become axiomatic that mechanical signals promote in vitro engineered tissue formation, the underlying mechanisms remain largely unknown. Moreover, efforts to date to determine parameters for optimal extracellular matrix (ECM) development have been largely empirical. In the present work, we propose a two-pronged approach involving novel theoretical developments coupled with key experimental data to develop better mechanistic understanding of growth and development of dense connective tissue under mechanical stimuli. To describe cellular proliferation and ECM synthesis that occur at rates of days to weeks, we employ mixture theory to model the construct constituents as a nutrient-cell-ECM triphasic system, their transport, and their biochemical reactions. Dynamic conditioning protocols with frequencies around 1 Hz are described with multi-scale methods to couple the dissimilar time scales. Enhancement of nutrient transport due to pore fluid advection is upscaled into the growth model, and the spatially dependent ECM distribution describes the evolving poroelastic characteristics of the scaffold-engineered tissue construct. Simulation results compared favorably to the existing experimental data, and most importantly, distinguish between static and dynamic conditioning regimes. The theoretical framework for mechanically conditioned tissue engineering (TE) permits not only the formulation of novel and better-informed mechanistic hypothesis describing the phenomena underlying TE growth and development, but also the exploration/optimization of conditioning protocols in a rational manner. PMID:26055347

  13. 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.

  14. 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.

  15. Toughened semicrystalline engineering polymers: Morphology, impact resistance, and fracture mechanisms

    SciTech Connect

    Flexman, E.A.

    1993-12-31

    Major factors that contribute to maximized impact resistance of semicrystalline engineering polymers include increased matrix molecular weight, minimal rubber glass-transition temperature, and optimal rubber-particle size, which depends on matrix type. Additional constraints are posed by the limitations of available materials and commercial requirements. Expanding the understanding of impact-modified crystalline engineering polymers will further extend their property ranges and utility. This chapter describes the phenomenology of certain factors, illustrates a new technique to measure rubber particle size, and contrasts the fracture mechanisms of poly(butylene terephthalate), nylon 66, and polyacetal. 49 refs., 24 figs.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. Evolution of pore fluid pressures in a stimulated geothermal reservoir inferred from earthquake focal mechanisms

    NASA Astrophysics Data System (ADS)

    Terakawa, T.; Deichmann, N.

    2014-12-01

    We developed an inversion method to estimate the evolution of pore fluid pressure fields from earthquake focal mechanism solutions based on the Bayesian statistical inference and Akaike's Bayesian information criterion (ABIC). This method's application to induced seismicity in the Basel enhanced geothermal system in Switzerland shows the evolution of pore fluid pressures in response to fluid injection experiments. For a few days following the initiation of the fluid injection, overpressurized fluids are concentrated around the borehole and then anisotropically propagate within the reservoir until the bleed-off time. Then, the pore fluid pressure in the vicinity of the borehole drastically decreases, and overpressurized fluids become isolated in a few major fluid pockets. The pore fluid pressure in these pockets gradually decreases with time. The pore fluid pressure in the reservoir is less than the minimum principal stress at each depth, indicating that the hydraulic fracturing did not occur during stimulation. This suggests that seismic events may play an important role to promote the development of permeable channels, particularly southeast of the borehole where the largest seismic event (ML 3.4) occurred. This is not directly related to a drastic decrease in fault strength at the hypocenter, but rather the positive feedback between permeability enhancement and poro-elastic and stress transfer loading from slipping interfaces. These processes likely contribute to this event's nucleation.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. Interstitial fluid pressure regulates collective invasion in engineered human breast tumors via Snail, vimentin, and E-cadherin.

    PubMed

    Piotrowski-Daspit, Alexandra S; Tien, Joe; Nelson, Celeste M

    2016-03-14

    Many solid tumors exhibit elevated interstitial fluid pressure (IFP). This elevated pressure within the core of the tumor results in outward flow of interstitial fluid to the tumor periphery. We previously found that the directionality of IFP gradients modulates collective invasion from the surface of patterned three-dimensional (3D) aggregates of MDA-MB-231 human breast cancer cells. Here, we used this 3D engineered tumor model to investigate the molecular mechanisms underlying IFP-induced changes in invasive phenotype. We found that IFP alters the expression of genes associated with epithelial-mesenchymal transition (EMT). Specifically, the levels of Snail, vimentin, and E-cadherin were increased under pressure conditions that promoted collective invasion. These changes in gene expression were sufficient to direct collective invasion in response to IFP. Furthermore, we found that IFP modulates the motility and persistence of individual cells within the aggregates, which are also influenced by the expression levels of EMT markers. Together, these data provide insight into the molecular mechanisms that guide collective invasion from primary tumors in response to IFP. PMID:26853861

  7. 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 to the Cardiovascular Laboratory and the Space Life Science Summer Institute, which helped me prepare for future graduate school research presentations. This internship allowed me to apply and expand the anatomy, physiology, and mechanics information I learned during my undergraduate degree in Biomedical Engineering to the cardiovascular system with the unique zero gravity perspective. Additionally, I was able to develop skills with data analysis techniques involving speckle tracking for ventricular strain and Doppler waveforms for blood velocities. Additionally, I was able to expand upon my previous work in the Cardiovascular Laboratory by writing a literature review on a data analysis project I completed last summer. Ultimately, this internship and venous relationship comparison project provided me with a significant learning experience and additional skill sets, which are applicable to my goals of attaining a Ph.D. in biomedical engineering with a focus on tissue engineering and the cardiovascular system.

  8. Microfabrication of hierarchical structures for engineered mechanical materials

    NASA Astrophysics Data System (ADS)

    Vera Canudas, Marc

    Materials found in nature present, in some cases, unique properties from their constituents that are of great interest in engineered materials for applications ranging from structural materials for the construction of bridges, canals and buildings to the fabrication of new lightweight composites for airplane and automotive bodies, to protective thin film coatings, amongst other fields. Research in the growing field of biomimetic materials indicates that the micro-architectures present in natural materials are critical to their macroscopic mechanical properties. A better understanding of the effect that structure and hierarchy across scales have on the material properties will enable engineered materials with enhanced properties. At the moment, very few theoretical models predict mechanical properties of simple materials based on their microstructures. Moreover these models are based on observations from complex biological systems. One way to overcome this challenge is through the use of microfabrication techniques to design and fabricate simple materials, more appropriate for the study of hierarchical organizations and microstructured materials. Arrays of structures with controlled geometry and dimension can be designed and fabricated at different length scales, ranging from a few hundred nanometers to centimeters, in order to mimic similar systems found in nature. In this thesis, materials have been fabricated in order to gain fundamental insight into the complex hierarchical materials found in nature and to engineer novel materials with enhanced mechanical properties. The materials fabricated here were mechanically characterized and compared to simple mechanics models to describe their behavior with the goal of applying the knowledge acquired to the design and synthesis of future engineered materials with novel properties.

  9. Mechanics of swimming at the small scale in complex fluids

    NASA Astrophysics Data System (ADS)

    Powers, Thomas

    2015-03-01

    Recent experiments with bacteria in liquid crystalline solutions have revealed that nematic order affects the swimming behavior of bacteria. Motivated by these observations, we study a simple model of low-Reynolds-number swimming in an anisotropic fluid, that of an infinitely long two-dimensional sheet deforming via propagating transverse or longitudinal waves and immersed in a hexatic or a nematic liquid crystal. The liquid crystal is categorized by the dimensionless Ericksen number Er, which compares viscous and elastic effects. Paying special attention to the anchoring strength at the interface of the liquid crystal and the swimmer, we calculate how swimming speed depends on Er for small amplitude waves. We study both the sinusoidal steady-state problem as well as the startup problem in which the swimmer starts from rest.

  10. Mechanical modeling of fluid-driven polymer lenses.

    PubMed

    Yang, Qingda; Kobrin, Paul; Seabury, Charles; Narayanaswamy, Sridhar; Christian, William

    2008-07-10

    A finite-element model (FEM) is employed to study the pressure response of deformable elastic membranes used as tunable optical elements. The model is capable of determining in situ both the modulus and the prestrain from a measurement of peak deflection versus pressure. Given accurate values for modulus and prestrain, it is shown that the two parameters of a standard optical shape function (radius of curvature and conic constant) can be accurately predicted. The effects of prestrain in polydimethylsiloxane (PDMS) membranes are investigated in detail. It was found that prestrain reduces the sensitivity of the membrane shape to the details of the edge clamping. It also reduces the variation of the conic constant with changes in curvature. Thus the ability to control the prestrain as well as thickness and modulus is important to developing robust optical designs based on fluid-driven polymer lenses. PMID:18617983

  11. 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.

  12. Numerical Simulation of the ``Fluid Mechanical Sewing Machine''

    NASA Astrophysics Data System (ADS)

    Brun, Pierre-Thomas; Audoly, Basile; Ribe, Neil

    2011-11-01

    A thin thread of viscous fluid falling onto a moving conveyor belt generates a wealth of complex ``stitch'' patterns depending on the belt speed and the fall height. To understand the rich nonlinear dynamics of this system, we have developed a new numerical code for simulating unsteady viscous threads, based on a discrete description of the geometry and a variational formulation for the viscous stresses. The code successfully reproduces all major features of the experimental state diagram of Morris et al. (Phys. Rev. E 2008). Fourier analysis of the motion of the thread's contact point with the belt suggests a new classification of the observed patterns, and reveals that the system behaves as a nonlinear oscillator coupling the pendulum modes of the thread.

  13. 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.

  14. 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)

  15. Coupled Hydro-Mechanical Modeling of Fluid Geological Storage

    NASA Astrophysics Data System (ADS)

    Castelletto, N.; Garipov, T.; Tchelepi, H. A.

    2013-12-01

    The accurate modeling of the complex coupled physical processes occurring during the injection and the post-injection period is a key factor for assessing the safety and the feasibility of anthropogenic carbon dioxide (CO2) sequestration in subsurface formations. In recent years, it has become widely accepted the importance of the coupling between fluid flow and geomechanical response in constraining the sustainable pressure buildup caused by fluid injection relative to the caprock sealing capacity, induced seismicity effects and ground surface stability [e.g., Rutqvist, 2012; Castelletto et al., 2013]. Here, we present a modeling approach based on a suitable combination of Finite Volumes (FVs) and Finite Elements (FEs) to solve the coupled system of partial differential equations governing the multiphase flow in a deformable porous medium. Specifically, a FV method is used for the flow problem while the FE method is adopted to address the poro-elasto-plasticity equations. The aim of the present work is to compare the performance and the robustness of unconditionally stable sequential-implicit schemes [Kim et al., 2011] and the fully-implicit method in solving the algebraic systems arising from the discretization of the governing equations, for both normally conditioned and severely ill-conditioned problems. The two approaches are tested against well-known analytical solutions and experimented with in a realistic application of CO2 injection in a synthetic aquifer. References: - Castelletto N., G. Gambolati, and P. Teatini (2013), Geological CO2 sequestration in multi-compartment reservoirs: Geomechanical challenges, J. Geophys. Res. Solid Earth, 118, 2417-2428, doi:10.1002/jgrb.50180. - Kim J., H. A. Tchelepi, and R. Juanes (2011), Stability, accuracy and efficiency of sequential methods for coupled flow and geomechanics, SPE J., 16(2), 249-262. - Rutqvist J. (2012), The geomechanics of CO2 storage in deep sedimentary formations, Geotech. Geol. Eng., 30, 525-551.

  16. 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... COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-9 Mechanical engine order telegraph systems. (a) Each mechanical engine order telegraph system must consist of transmitters...

  17. The brain Renin-angiotensin system controls divergent efferent mechanisms to regulate fluid and energy balance.

    PubMed

    Grobe, Justin L; Grobe, Connie L; Beltz, Terry G; Westphal, Scott G; Morgan, Donald A; Xu, Di; de Lange, Willem J; Li, Huiping; Sakai, Koji; Thedens, Daniel R; Cassis, Lisa A; Rahmouni, Kamal; Mark, Allyn L; Johnson, Alan Kim; Sigmund, Curt D

    2010-11-01

    The renin-angiotensin system (RAS), in addition to its endocrine functions, plays a role within individual tissues such as the brain. The brain RAS is thought to control blood pressure through effects on fluid intake, vasopressin release, and sympathetic nerve activity (SNA), and may regulate metabolism through mechanisms which remain undefined. We used a double-transgenic mouse model that exhibits brain-specific RAS activity to examine mechanisms contributing to fluid and energy homeostasis. The mice exhibit high fluid turnover through increased adrenal steroids, which is corrected by adrenalectomy and attenuated by mineralocorticoid receptor blockade. They are also hyperphagic but lean because of a marked increase in body temperature and metabolic rate, mediated by increased SNA and suppression of the circulating RAS. β-adrenergic blockade or restoration of circulating angiotensin-II, but not adrenalectomy, normalized metabolic rate. Our data point to contrasting mechanisms by which the brain RAS regulates fluid intake and energy expenditure. PMID:21035755

  18. The Brain Renin-Angiotensin System Controls Divergent Efferent Mechanisms to Regulate Fluid and Energy Balance

    PubMed Central

    Grobe, Justin L.; Grobe, Connie L.; Beltz, Terry G.; Westphal, Scott G.; Morgan, Donald A.; Xu, Di; de Lange, Willem J.; Li, Huiping; Sakai, Koji; Thedens, Daniel R.; Cassis, Lisa A.; Rahmouni, Kamal; Mark, Allyn L.; Johnson, Alan Kim; Sigmund, Curt D.

    2010-01-01

    Summary The renin-angiotensin system (RAS), in addition to its endocrine functions, plays a role within individual tissues such as the brain. The brain RAS is thought to control blood pressure through effects on fluid intake, vasopressin release and sympathetic nerve activity (SNA), and may regulate metabolism through mechanisms which remain undefined. We used a double-transgenic mouse model that exhibits brain-specific RAS activity to examine mechanisms contributing to fluid and energy homeostasis. The mice exhibit high fluid turnover through increased adrenal steroids, which is corrected by adrenalectomy and attenuated by mineralocorticoid receptor blockade. They are also hyperphagic but lean because of a marked increase in body temperature and metabolic rate, mediated by increased SNA and suppression of the circulating RAS. β-adrenergic blockade or restoration of circulating angiotensin-II, but not adrenalectomy, normalized metabolic rate. Our data point to contrasting mechanisms by which the brain RAS regulates fluid intake and energy expenditure. PMID:21035755

  19. Transcytosis in the blood–cerebrospinal fluid barrier of the mouse brain with an engineered receptor/ligand system

    PubMed Central

    Méndez-Gómez, Héctor R; Galera-Prat, Albert; Meyers, Craig; Chen, Weijun; Singh, Jasbir; Carrión-Vázquez, Mariano; Muzyczka, Nicholas

    2015-01-01

    Crossing the blood–brain and the blood–cerebrospinal fluid barriers (BCSFB) is one of the fundamental challenges in the development of new therapeutic molecules for brain disorders because these barriers prevent entry of most drugs from the blood into the brain. However, some large molecules, like the protein transferrin, cross these barriers using a specific receptor that transports them into the brain. Based on this mechanism, we engineered a receptor/ligand system to overcome the brain barriers by combining the human transferrin receptor with the cohesin domain from Clostridium thermocellum, and we tested the hybrid receptor in the choroid plexus of the mouse brain with a dockerin ligand. By expressing our receptor in choroidal ependymocytes, which are part of the BCSFB, we found that our systemically administrated ligand was able to bind to the receptor and accumulate in ependymocytes, where some of the ligand was transported from the blood side to the brain side. PMID:26491705

  20. 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.

  1. 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 thanks to the expert reviewers who have spared their time reviewing the papers. We also highly appreciate the assistance offered by many volunteers in the preparation of the conference proceedings. All papers in ICMER 2011 have the opportunity to be published in IOP Conference Series: Materials Science and Engineering, (indexed by Scopus, Ei Compendex, Inspec), International Journal of Automotive and Mechanical Engineering (IJAME) and Journal of Mechanical Engineering and Sciences (JMES). Professor Dr Hj Rosli Abu Bakar Chairman ICMER 2011

  2. Magnetoreological Fluid Template for Basic Studies of Mechanical-Chemical Effects During Polishing

    SciTech Connect

    Miao, C.; Bristol, K. M.; Marino, A.E.; Shafrir, S.N.; DeGroote, J.E.; Jacobs, S.D.

    2008-01-07

    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 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 formation, 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. 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.

  3. 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.

  4. Commercial solar/load management experiment: New mechanical engineering building

    NASA Astrophysics Data System (ADS)

    Noble, J. M.

    1981-01-01

    The effects of load management heat recovery, thermal storage, and solar systems on energy usage and power demand profiles in the University of New Mexico's Mechanical Engineering Building are presented. Results were obtained from a year monitoring of the building's heating and cooling systems and recording of sensor signals by a computer based data acquisition system. A modified AXCESS Energy Analysis Program to simulate energy usage is detailed, and the development of perferred strategies for maximizing the building's load management capabilities is outlined.

  5. 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).

  6. 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 positive feedback from students, the course will now be offered regularly as a senior design class which will also fulfill engineering graduation requirements.

  7. 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.

  8. Content of a Graduate Course in Fluid Mechanics

    NASA Astrophysics Data System (ADS)

    Panton, Ronald

    2006-11-01

    This talk will give some of my personal choices for educating specialists in fluid flow. The first course should emphasize physics and leave CFD, turbulence, microflows, surface tension flows, and other specialties to separate courses. General topics that should be covered include: concepts and definitions; physical and viscous laws; control volume laws; local laws; elemental flow situations; dimensional analysis, and the characteristics of different flow categories (Stokes flow, lubrication theory, ideal flow, boundary layers, etc.). At the graduate level, more precision and rigor is desired. Exact solutions are valuable as examples of physical events and as illustrations of trends for concepts and properties. The availability of Excel, Mathcad, or Matlab allows students to investigate and visualize flow properties and their trends with parameters. Dimensional analysis should not end with correlations and similarity, but also emphasize variable scaling, variable references, and proper forms for limiting parameters to extreme values. Graduate students need to view flow categories as parameter limits for certain boundary conditions. Asymptotic expansions are a formal mathematical structure for flow categories. I use the Jeffrey-Hammel wedge flow as an exact solution that demonstrates the various categories of incompressible flows for all Reynolds number limits. An integrated knowledge of physics is an advanced viewpoint that extends specific knowledge of a series of flow patterns.

  9. 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.

  10. Adaptive local grid refinement in computational fluid mechanics

    NASA Astrophysics Data System (ADS)

    Ewing, Richard E.; Allen, Myron B.; Djomehri, M. J.; George, John H.; Isaacson, Eli L.

    1987-11-01

    Several promising new techniques for efficient and accurate numerical solution of large-scale fluid flow problems have been developed. These methods include self-adaptive mesh modification techniques for applications requiring front-tracking and local grid refinement as well as new preconditioning ideas for efficient implementation. Properties of systems of hyperbolic conservation laws have been obtained which will aid in development of accurate front-tracking algorithms. Adaptive grid refinement techniques developed include moving grid methods, local, fixed refinement involving linked-list data structures, and certain local patch refinement ideas which have great potential for ease of implementation in existing large scale codes. Domain decomposition concepts for obtaining efficient preconditioners for iterative techniques have proved quite useful both for local patch refinement and for the solution of problems with rapidly varying coefficients. The fast adaptive algorithms being developed have high potential for both parallelization and vectorization. The algorithms have been designed to take advantage of the emerging parallel and vector-oriented computer architectures. Finally, the incorporation of these fast algorithms in accurate finite element, collocation, and finite difference methods is underway.

  11. 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?

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. A semi-active magnetorheological fluid mechanism with variable stiffness and damping

    NASA Astrophysics Data System (ADS)

    Greiner-Petter, Christoph; Suryadi Tan, Aditya; Sattel, Thomas

    2014-10-01

    In this paper a semi-active fluid-mechanism is presented, which offers a variable stiffness and damping by utilizing two magnetorheological fluid valves and two springs. The study incorporates the attributes of variable damping and stiffness into one compact device. A model for the magnetical, rheological, fluidical and mechanical behaviour of the whole system is derived. An experimental setup of the proposed system and an appropriate test bench are built in order to study the variable mechanical impedance behaviour with the corresponding simulations. The results proof that the stiffness of the system can be varied among three different values, while its damping is continuously variable.

  18. 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.

  19. 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...-15 Mechanical engine order telegraph systems; application. If a mechanical engine order telegraph... cables or other mechanical limitations must not prevent the efficient operation of the system....

  20. 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 in some detail, as are permeabilities of some of the simpler types of fractured materials.

  1. 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-oxygenhydrogen and n-decanegaseous-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.

  2. 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.

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

    DOE PAGESBeta

    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

  4. Coupling of hierarchical fluid models with electrostatic and mechanical models for the dynamic analysis of MEMS

    NASA Astrophysics Data System (ADS)

    De, Sudipto K.; Aluru, N. R.

    2006-08-01

    The dynamical behavior of MEMS (micro-electro-mechanical systems) is often strongly affected by viscous fluid/air damping effects from the surrounding. These fluid/air damping effects have to be carefully taken into account during the design and optimization process, in order to get a realistic and reliable description of the device operation. In this paper, two hierarchical fluid models (the 2D compressible Reynold's squeeze film equation and the 2D compressible Navier-Stokes equations) are coupled with a 2D electro-mechanical solver for the dynamic analysis of MEMS to simulate and understand the effect of fluid damping on microstructures. The different physical domains (electrical, mechanical and fluidic) are coupled together using a Newton method for faster convergence. A Lagrangian description of all the physical domains makes it possible to compute the inter-domain coupling terms in the Jacobian matrix of the Newton method exactly. Several MEMS devices (a micromirror, a piggyback actuator, a lateral comb drive and a cantilever beam in air) have been simulated using the coupled electro-mechanical-fluidic solver and numerical results on the resonant frequency and the quality factor are compared with experimental data. The two hierarchical fluid models can be used judiciously (based on speed and accuracy) along with the electro-mechanical solver, depending on the type of MEMS device under consideration, thereby making the dynamic analysis of MEMS devices more efficient.

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

    NASA Astrophysics Data System (ADS)

    Lecheva, A.; Zheleva, I.

    2015-10-01

    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.

  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. 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.

  8. 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

  9. Dynamical analysis of fluid lines coupled to mechanical systems taking into account fluid frequency-dependent damping and non-conventional constitutive models: part 1 - Modeling fluid lines

    NASA Astrophysics Data System (ADS)

    Catania, Giuseppe; Sorrentino, Silvio

    2015-01-01

    The design of hydraulic transmission systems for control and actuation requires accurate knowledge of their dynamic response: some standard techniques are known to obtain a consistent dynamic model of a fluid line, including the contribution of inertia, compressibility and friction. In this paper an efficient procedure is developed for simulating the dynamic response of a fluid line in both the frequency and time domains, focusing the attention on the modal analysis of a discretized model, in view of coupling with mechanical systems. A bi-dimensional approach is adopted, and the laminar flow frequency-dependent friction is modeled using non-integer order differential laws, which may improve the accuracy of the simulated responses in comparison with more traditional Newtonian models.

  10. A novel coarsening mechanism of droplets in immiscible fluid mixtures.

    PubMed

    Shimizu, Ryotaro; Tanaka, Hajime

    2015-01-01

    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. PMID:26077672

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. 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...

  1. 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...

  2. 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...

  3. 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...

  4. 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.

  5. 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. )

  6. 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. PMID:23962885

  7. New Developments of Computational Fluid Dynamics and Their Applications to Practical Engineering Problems

    NASA Astrophysics Data System (ADS)

    Chen, Hudong

    2001-06-01

    There have been considerable advances in Lattice Boltzmann (LB) based methods in the last decade. By now, the fundamental concept of using the approach as an alternative tool for computational fluid dynamics (CFD) has been substantially appreciated and validated in mainstream scientific research and in industrial engineering communities. Lattice Boltzmann based methods possess several major advantages: a) less numerical dissipation due to the linear Lagrange type advection operator in the Boltzmann equation; b) local dynamic interactions suitable for highly parallel processing; c) physical handling of boundary conditions for complicated geometries and accurate control of fluxes; d) microscopically consistent modeling of thermodynamics and of interface properties in complex multiphase flows. It provides a great opportunity to apply the method to practical engineering problems encountered in a wide range of industries from automotive, aerospace to chemical, biomedical, petroleum, nuclear, and others. One of the key challenges is to extend the applicability of this alternative approach to regimes of highly turbulent flows commonly encountered in practical engineering situations involving high Reynolds numbers. Over the past ten years, significant efforts have been made on this front at Exa Corporation in developing a lattice Boltzmann based commercial CFD software, PowerFLOW. It has become a useful computational tool for the simulation of turbulent aerodynamics in practical engineering problems involving extremely complex geometries and flow situations, such as in new automotive vehicle designs world wide. In this talk, we present an overall LB based algorithm concept along with certain key extensions in order to accurately handle turbulent flows involving extremely complex geometries. To demonstrate the accuracy of turbulent flow simulations, we provide a set of validation results for some well known academic benchmarks. These include straight channels, backward-facing steps, flows over a curved hill and typical NACA airfoils at various angles of attack including prediction of stall angle. We further provide numerous engineering cases, ranging from external aerodynamics around various car bodies to internal flows involved in various industrial devices. We conclude with a discussion of certain future extensions for complex fluids.

  8. Colloidal binary mixtures at fluid-fluid interfaces under steady shear: structural, dynamical and mechanical response.

    PubMed

    Buttinoni, Ivo; Zell, Zachary A; Squires, Todd M; Isa, Lucio

    2015-11-14

    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

  9. A turnstile mechanism for fronts propagating in fluid flows.

    PubMed

    Mahoney, John R; Mitchell, Kevin A

    2013-12-01

    We consider the propagation of fronts in a periodically driven flowing medium. It is shown that the progress of fronts in these systems may be mediated by a turnstile mechanism akin to that found in chaotic advection. We first define the modified ("active") turnstile lobes according to the evolution of point sources across a transport boundary. We then show that the lobe boundaries may be constructed from stable and unstable burning invariant manifolds (BIMs)--one-way barriers to front propagation analogous to traditional invariant manifolds for passive advection. Because the BIMs are one-dimensional curves in a three-dimensional (xyθ) phase space, their projection into xy-space exhibits several key differences from their advective counterparts: (lobe) areas are not preserved, BIMs may self-intersect, and an intersection between stable and unstable BIMs does not map to another such intersection. These differences must be accommodated in the correct construction of the new turnstile. As an application, we consider a lobe-based treatment protocol for protecting an ocean bay from an invading algae bloom. PMID:24387545

  10. Reaction Engineering International and Pacific Northwest Laboratory staff exchange: Addressing computational fluid dynamics needs of the chemical process industry

    SciTech Connect

    Fort, J.A.

    1995-07-01

    Staff exchanges, such as the one described in this report, are intended to facilitate communications and collaboration among scientists and engineers at Department of Energy (DOE) laboratories, in US industry, and academia. Funding support for these exchanges is provided by the DOE, Office of Energy Research, Laboratory Technology Transfer Program. Funding levels for each exchange typically range from $20,000 to $40,000. The exchanges offer the opportunity for the laboratories to transfer technology and expertise to industry, gain a perspective to industry`s problems, and develop the basis for further cooperative efforts through Cooperative Research and Development Agreements (CRADAS) or other mechanisms. Information in this report on the staff exchange of the Pacific Northwest Laboratory (PNL) staff with Reaction Engineering International (REI) includes the significant accomplishments, significant problems, industry benefits realized, recommended follow-on work and potential benefit of that work. The objectives of this project were as follows: Work with REI to develop an understanding of the computational fluid dynamics (CFD) needs of the chemical process industry; assess the combined capabilities of the PNL and REI software analysis tools to address these needs; and establish a strategy for a future programmatically funded, joint effort to develop a new CFD tool for the chemical process industry.

  11. 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

  12. Shape matters: Near-field fluid mechanics dominate the collective motions of ellipsoidal squirmers

    NASA Astrophysics Data System (ADS)

    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.

  13. 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.

  14. 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

  15. 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.

  16. Evolution of pore fluid pressures in a stimulated geothermal reservoir inferred from earthquake focal mechanisms

    NASA Astrophysics Data System (ADS)

    Terakawa, Toshiko

    2014-11-01

    This paper proposes an inversion method to estimate the evolution of pore fluid pressure fields from earthquake focal mechanism solutions. Application of the method to induced seismicity in the Basel enhanced geothermal system in Switzerland shows the evolution of pore fluid pressure in response to fluid injection experiments. The pore fluid pressure in the reservoir was less than the minimum principal stress at each depth, indicating that hydraulic fracturing did not occur during the stimulation. This suggests that seismic events may play an important role in promoting the development of permeable channels, particularly southeast of the borehole where the largest seismic event (Mw 2.95) occurred. This is not directly related to a drastic decrease in fault strength at the hypocenter but rather to positive feedback between permeability enhancement and elastic/poroelastic stress loading from slipping interfaces.

  17. 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.

  18. 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 injected. The most remarkable difference is that water injection induces mechanical instability and failure, whereas oil injection does not. This was confirmed by the analysis of acoustic emissions activity and post-mortem sample imaging using CT scan. Contrasting evolutions of the P wave velocity during the fluid front propagation were also observed in both experiments.

  19. 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 0.15% to 0.25% full scale. PMID:23644779

  20. 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

  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. Thermal-mechanical fatigue crack growth in aircraft engine materials

    NASA Astrophysics Data System (ADS)

    Dai, Yi

    1993-05-01

    A thermal mechanical fatigue (TMF) testing rig was built which is capable of studying the fatigue behaviors of gas turbine engine materials under simultaneous changes of temperatures and strains or stress. An advance alternating current potential drop (ACPD) measurement system was also developed which is capable of performing on-line monitoring of fatigue crack initiation and growth in specimen testing under isothermal and TMF conditions. Fatigue crack initiation and short crack growth data were obtained for titanium alloy specimens designed with notch features associated with bolt holes of compressor discs. TMF data were also obtained for two titanium alloys used in aircraft engine components. Those data explained the material fatigue behavior encountered in full-scale component testing. A complete fractographic analysis was performed on the tested specimens enhancing the understanding of the fatigue crack growth mechanisms and helping to formulate an analytical crack growth model. The ACPD fatigue crack monitoring technique was applied to the low cycle fatigue testing of Pratt & Whitney 1480 monocrystalline nickel alloy. A completely automated, computer controlled test procedure was developed which could obtain crack initiation and growth data with greater speed, precision, and reliability than previous methods.

  3. Mechanical regulation of vascular network formation in engineered matrices.

    PubMed

    Lesman, Ayelet; Rosenfeld, Dekel; Landau, Shira; Levenberg, Shulamit

    2016-01-15

    Generation of vessel networks within engineered tissues is critical for integration and perfusion of the implanted tissue in vivo. The effect of mechanical cues in guiding and stabilizing the vessels has begun to attract marked interest. This review surveys the impact of mechanical cues on formation of vascular networks in 2D and 3D gel matrices. We give less emphasis to regulation of endothelial monolayers and single endothelial cells. Several vascularization models have consistently found that the stress generated in the gel, and encountered by embedded cells, control various aspects of vascular network formation, including sprouting, branching, alignment, and vessel maturation. This internal stress is generated by cell contractile forces, and is balanced by gel stiffness and boundary constrains imposed on the gel. Actin and myosin II are key molecular players in controlling initiation of vessel sprouting and branching morphogenesis. Additionally, the impact of external mechanical cues on tissue vascularization, and studies supporting the notion that mechanical forces regulate vascularization in the live animal are reviewed. PMID:26212159

  4. 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

  5. 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…

  6. 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…

  7. 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.

  8. Dynamic response analysis of a solar powered heliotropic fluid-mechanical drive system

    NASA Astrophysics Data System (ADS)

    Cope, N. A.; Ingley, H. A.; Farber, E. A.; Morrison, C. A.

    This paper provides a summary of work performed during the design, construction, and subsequent analysis of a solar powered tracking mechanism. The mechanism utilizes basic mechanical and thermodynamic principles in its construction and operation. Data taken during the course of the research and reported in this paper reveal that with a particular combination of system components and working fluid, a high degree of accuracy and wind stability can be achieved with this device when used to drive large concentrating solar collectors. The tracking mechanism was found to be fully self-correcting during normal daily operation and to reorient itself to the morning sun.

  9. 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.

  10. Mechanisms of Surface Wave Energy Dissipation over a Fluid Mud Sediment Suspension

    NASA Astrophysics Data System (ADS)

    Traykovski, P.; Trowbridge, J. H.; Kineke, G. C.

    2014-12-01

    Field observations from the spring of 2008 on the Louisiana shelf were used to elucidate the mechanisms of wave energy dissipation over a muddy seafloor. After a period of high discharge from the Atchafalaya River acoustic measurements showed the presence of 20 cm thick mobile fluid mud layers during and after wave events. While total wave energy dissipation (D) was greatest during the high energy periods, these periods had relatively low normalized attenuation rates (? = Dissipation/Energy Flux). During declining wave energy conditions, as the fluid mud layer settled, the attenuation process became more efficient with high ? and low D. The transition from high D and low ? to high ? and low D was caused by a transition from turbulent to laminar flow in the fluid mud layer as measured by a Pulse-coherent Doppler profiler. Measurements of the oscillatory boundary layer velocity profile in the fluid mud layer during laminar flow reveal a very thick wave boundary layer with curvature filling the entire fluid mud layer, suggesting a kinematic viscosity two to three orders of magnitude greater than clear water. This high viscosity is also consistent with a high wave attenuation rates measured by across shelf energy flux differences. The transition to turbulence was forced by instabilities on the lutocline, with wavelengths consistent with the dispersion relation for this two layer system. The measurements also provide new insight into the dynamics of wave supported turbidity flows during the transition from a laminar to turbulent fluid mud layer.

  11. Quantitative analysis of three-dimensional fluid flow in rotating bioreactors for tissue engineering.

    PubMed

    Botchwey, Edward A; Pollack, Solomon R; Levine, Elliot M; Johnston, Eric D; Laurencin, Cato T

    2004-05-01

    Tissue engineering has emerged as a viable alternative to the problem of organ and tissue shortage. Our laboratory has developed matrices for bone tissue engineering based on sintered spherical particles and, using bioreactor technology, has demonstrated the ability to produce highly mineralized matrices in vitro. In this study, porous microcapsule scaffolds were developed for bone tissue engineering in the high aspect ratio vessel rotating bioreactor. The motion of individual microcapsules as well as scaffolds in the bioreactor were studied by numerical simulation and in situ imaging analysis. Results show that spherical microcapsules with density less than the surrounding fluid exhibited two motions: (1) a periodic circular orbit with tangential speed equal to the free fall speed of the particle, and (2) an inward radial migration of the circular orbit toward the center of the bioreactor vessel. Lighter-than-water scaffolds were fabricated by sintering poly(lactic-co-glycolic acid) hollow microcarriers with diameter from 500 to 860 microm into a fixed three-dimensional geometry with approximately 30% pore volume and 180 to 190 microm median pore size. Scaffolds were fabricated with aggregate densities ranging from 0.65 g/mL and 0.99 g/mL by appropriate combinations of hollow and solid microcarriers within the scaffold. Scaffold velocity in the bioreactor for the above range of densities was accurately predicted by numerical simulation and ranged from 100 mm/s to 3 mm/s. Maximum shear stress estimation due to media flow over the exterior of the scaffold ranged from 0.3 N/m(2) to 0.006 N/m(2). Internal perfusion velocity through scaffolds also was calculated and ranged from 13 mm/s to 0.2 mm/s. Estimates of maximum interior shear stress ranged from 0.03 to 0.0007 N/m(2). These analytical methods provide an excellent vehicle for the study of bone tissue synthesis in three-dimensional culture with fluid flow. PMID:15057993

  12. 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.

  13. 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.

  14. Flow resistance in natural, turbulent channel flows: The need for a fluvial fluid mechanics

    NASA Astrophysics Data System (ADS)

    Keylock, Christopher J.

    2015-06-01

    In fluvial environments, feedbacks among flow, bed forms, sediment, and macrophytes result in a complex fluid dynamics. The assumptions underpinning standard tools in hydraulics are commonly violated and alternative approaches must be formulated. I argue that we should question the assumption that classical notions in fluid mechanics provide the foundations for the techniques of the future. Recent work on turbulent dissipation, interscale modulation of the dynamics, intermittency, and the role of complex forcings is discussed. An agenda for future work is proposed that involves improving our characterization of complex forcings and developing better understanding of the behavior of the velocity gradient tensor in complex, fluvial environments. This leads to the formulation of modeling tools relevant to fluvial fluid mechanics, rather than a reliance on methods developed elsewhere. One avenue by which such methods might be developed is suggested based on the stretched spiral vortex as a baseline topology. This would result in a nonequilibrium model for turbulence that has greater potential to capture the dynamics in which we are interested. Although these ideas are raised in the context of a future fluvial fluid mechanics, they are applicable to any situation where turbulent flows are forced in complicated ways.

  15. Fully coupled thermal-mechanical-fluid flow model for nonliner geologic systems

    SciTech Connect

    Hart, R.D.

    1981-01-01

    A single model is presented which describes fully coupled thermal-mechanical-fluid flow behavior of highly nonlinear, dynamic or quasistatic, porous geologic systems. The mathematical formulation for the model utilizes the continuum theory of mixtures to describe the multiphase nature of the system, and incremental linear constitutive theory to describe the path dependency of nonlinear material behavior. The model, incorporated in an explicit finite difference numerical procedure, was implemented in two different computer codes. A special-purpose one-dimensional code, SNEAKY, was written for initial validation of the coupling mechanisms and testing of the coupled model logic. A general purpose commercially available code, STEALTH, developed for modeling dynamic nonlinear thermomechanical processes, was modified to include fluid flow behavior and the coupling constitutive model. The fully explicit approach in the coupled calculation facilitated the inclusion of the coupling mechanisms and complex constitutive behavior. Analytical solutions pertaining to consolidation theory for soils, thermoelasticity for solids, and hydrothermal convection theory provided verification of stress and fluid flow, stress and conductive heat transfer, and heat transfer and fluid flow couplings, respectively, in the coupled model. A limited validation of the adequacy of the coupling constitutive assumptions was also performed by comparison with the physical response from two laboratory tests. Finally, the full potential of the coupled model is illustrated for geotechnical applications in energy-resource related areas. Examples in the areas of nuclear waste isolation and cut-and-fill mining are cited.

  16. 14 CFR 25.1182 - Nacelle areas behind firewalls, and engine pod attaching structures containing flammable fluid...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Nacelle areas behind firewalls, and engine pod attaching structures containing flammable fluid lines. 25.1182 Section 25.1182 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES...

  17. 14 CFR 25.1182 - Nacelle areas behind firewalls, and engine pod attaching structures containing flammable fluid...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Nacelle areas behind firewalls, and engine pod attaching structures containing flammable fluid lines. 25.1182 Section 25.1182 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES...

  18. Mechanisms of fluid movement into, through and out of the brain: evaluation of the evidence.

    PubMed

    Hladky, Stephen B; Barrand, Margery A

    2014-01-01

    Interstitial fluid (ISF) surrounds the parenchymal cells of the brain and spinal cord while cerebrospinal fluid (CSF) fills the larger spaces within and around the CNS. Regulation of the composition and volume of these fluids is important for effective functioning of brain cells and is achieved by barriers that prevent free exchange between CNS and blood and by mechanisms that secrete fluid of controlled composition into the brain and distribute and reabsorb it. Structures associated with this regular fluid turnover include the choroid plexuses, brain capillaries comprising the blood-brain barrier, arachnoid villi and perineural spaces penetrating the cribriform plate. ISF flow, estimated from rates of removal of markers from the brain, has been thought to reflect rates of fluid secretion across the blood-brain barrier, although this has been questioned because measurements were made under barbiturate anaesthesia possibly affecting secretion and flow and because CSF influx to the parenchyma via perivascular routes may deliver fluid independently of blood-brain barrier secretion. Fluid secretion at the blood-brain barrier is provided by specific transporters that generate solute fluxes so creating osmotic gradients that force water to follow. Any flow due to hydrostatic pressures driving water across the barrier soon ceases unless accompanied by solute transport because water movements modify solute concentrations. CSF is thought to be derived primarily from secretion by the choroid plexuses. Flow rates measured using phase contrast magnetic resonance imaging reveal CSF movements to be more rapid and variable than previously supposed, even implying that under some circumstances net flow through the cerebral aqueduct may be reversed with net flow into the third and lateral ventricles. Such reversed flow requires there to be alternative sites for both generation and removal of CSF. Fluorescent tracer analysis has shown that fluid flow can occur from CSF into parenchyma along periarterial spaces. Whether this represents net fluid flow and whether there is subsequent flow through the interstitium and net flow out of the cortex via perivenous routes, described as glymphatic circulation, remains to be established. Modern techniques have revealed complex fluid movements within the brain. This review provides a critical evaluation of the data. PMID:25678956

  19. 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.

  20. First Year Experiences in School of Mechanical Engineering Kanazawa University

    NASA Astrophysics Data System (ADS)

    Kinari, Toshiyasu; Kanjin, Yuichi; Furuhata, Toru; Tada, Yukio

    This paper reports two lectures of the first year experience, ‧Lecture on Life in Campus and Society‧ and ‧Freshman Seminar‧ and discusses their effects. Both lectures have been given freshmen of the school of mechanical engineering, Kanazawa University in H20 spring term. The former lecture is aimed at freshmen to keep on a proper way in both social and college life. It consists of normal class and e-learning system lectures. E-learning system examination requires students to review the whole text book and that seems to have brought better results in the survey. The latter seminar is aimed at freshmen to get active and self-disciplined learning way through their investigation, discussion, presentation, writing work, and so on.

  1. Critical Performance of Turbopump Mechanical Elements for Rocket Engine

    NASA Astrophysics Data System (ADS)

    Takada, Satoshi; Kikuchi, Masataka; Sudou, Takayuki; Iwasaki, Fumiya; Watanabe, Yoshiaki; Yoshida, Makoto

    It is generally acknowledged that bearings and axial seals have a tendency to go wrong compared with other rocket engine elements. And when those components have malfunction, missions scarcely succeed. However, fundamental performance (maximum rotational speed, minimum flow rate, power loss, durability, etc.) of those components has not been grasped yet. Purpose of this study is to grasp a critical performance of mechanical seal and hybrid ball bearing of turbopump. In this result, it was found that bearing outer race temperature and bearing coolant outlet temperature changed along saturation line of liquid hydrogen when flow rate was decreased under critical pressure. And normal operation of bearing was possible under conditions of more than 70,000 rpm of rotational speed and more than 0.2 liter/s of coolant flow rate. Though friction coefficient of seal surface increased several times of original value after testing, the seal showed a good performance same as before.

  2. Mechanical Control of Graphene on Engineered Pyramidal Strain Arrays.

    PubMed

    Gill, Stephen T; Hinnefeld, John H; Zhu, Shuze; Swanson, William J; Li, Teng; Mason, Nadya

    2015-06-23

    Strain can tune desirable electronic behavior in graphene, but there has been limited progress in controlling strain in graphene devices. In this paper, we study the mechanical response of graphene on substrates patterned with arrays of mesoscale pyramids. Using atomic force microscopy, we demonstrate that the morphology of graphene can be controlled from conformal to suspended depending on the arrangement of pyramids and the aspect ratio of the array. Nonuniform strains in graphene suspended across pyramids are revealed by Raman spectroscopy and supported by atomistic modeling, which also indicates strong pseudomagnetic fields in the graphene. Our results suggest that incorporating mesoscale pyramids in graphene devices is a viable route to achieving strain-engineering of graphene. PMID:25970764

  3. Quantitative Ultrasonic Evaluation of Mechanical Properties of Engineering Materials

    NASA Technical Reports Server (NTRS)

    Vary, A.

    1978-01-01

    Progress in the application of ultrasonic techniques to nondestructive measurement of mechanical strength of engineering materials is reviewed. A dormant concept in nondestructive evaluation (NDE) is invoked. The availability of ultrasonic methods that can be applied to actual parts to assess their potential susceptibility to failure under design conditions is discussed. It was shown that ultrasonic methods yield measurements of elastic moduli, microstructure, hardness, fracture toughness, tensile strength, yield strength, and shear strength for a wide range of materials (including many types of metals, ceramics, and fiber composites). It was also indicated that although most of these methods were shown feasible in laboratory studies, more work is needed before they can be used on actual parts in processing, assembly, inspection, and maintenance lines.

  4. 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…

  5. Effects of freezing-induced cell-fluid-matrix interactions on the cells and extracellular matrix of engineered tissues

    PubMed Central

    Teo, Ka Yaw; DeHoyos, Tenok O.; Dutton, J. Craig; Grinnell, Frederick; Han, Bumsoo

    2011-01-01

    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 a pre-developed cryopreservation protocol. PMID:21549425

  6. 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).

  7. 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 occurs under condition where the upstream pressure gradient is higher and the non-uniformity spacing is larger while mechanical dispersion is taken into consideration.

  8. Thermal fluid-solid interaction model and experimental validation for hydrostatic mechanical face seals

    NASA Astrophysics Data System (ADS)

    Huang, Weifeng; Liao, Chuanjun; Liu, Xiangfeng; Suo, Shuangfu; Liu, Ying; Wang, Yuming

    2014-09-01

    Hydrostatic mechanical face seals for reactor coolant pumps are very important for the safety and reliability of pressurized-water reactor power plants. More accurate models on the operating mechanism of the seals are needed to help improve their performance. The thermal fluid-solid interaction (TFSI) mechanism of the hydrostatic seal is investigated in this study. Numerical models of the flow field and seal assembly are developed. Based on the mechanism for the continuity condition of the physical quantities at the fluid-solid interface, an on-line numerical TFSI model for the hydrostatic mechanical seal is proposed using an iterative coupling method. Dynamic mesh technology is adopted to adapt to the changing boundary shape. Experiments were performed on a test rig using a full-size test seal to obtain the leakage rate as a function of the differential pressure. The effectiveness and accuracy of the TFSI model were verified by comparing the simulation results and experimental data. Using the TFSI model, the behavior of the seal is presented, including mechanical and thermal deformation, and the temperature field. The influences of the rotating speed and differential pressure of the sealing device on the temperature field, which occur widely in the actual use of the seal, are studied. This research proposes an on-line and assembly-based TFSI model for hydrostatic mechanical face seals, and the model is validated by full-sized experiments.

  9. Development of fluid overpressures in crustal faults and implications for earthquakes mechanics

    NASA Astrophysics Data System (ADS)

    Leclère, Henri; Cappa, Frédéric; Faulkner, Daniel; Armitage, Peter; Blake, Oshaine; Fabbri, Olivier

    2013-04-01

    The development and maintenance of fluid overpressures strongly influence the mechanical behavior of the crust and especially crustal fault zones. The mechanisms allowing fluid pressure build-up are still open questions, and their influence on tectonic and fault weakening processes remain unclear. The determination of the hydraulic and mechanical properties of crustal fault zone elements is a key aspect to improve our understanding of the fluid-tectonic interactions and more particularly the role of fluids in fault mechanics and earthquake triggering. Here we address this question combining geological observations, laboratory experiments and hydromechanical models of an active crustal fault-zone in the Ubaye-Argentera area (southeastern France). Previous studies showed that the fluids located in the fault zone developed overpressures between 7 and 26 MPa, that triggered intense seismic swarms (i.e. 16,000 events in 2003-2004) (Jenatton et al., 2007; Daniel et al., 2011; Leclère et al., 2012). The fault-zone studied here is located in the Argentera external crystalline massif and is connected to regional NW-SE steeply-dipping dextral strike-slip faults with an offset of several kilometers. The fault zone cuts through migmatitic gneisses composed of quartz, K-feldspar, plagioclase, biotite and minor muscovite. It exposes several anastomosed core zones surrounded by damage zones with a pluri-decametric total width. The core zones are made up of centimetric to pluridecimetric phyllosilicate-rich gouge layers while the damage zones are composed of pluri-metric phyllonitic rock derived from mylonite. The permeability and elastic moduli of the host rock, damage zone and fault core were measured from plugs with a diameter of 20 mm and lengths between 26 to 51 mm, using a high-pressure hydrostatic fluid-flow apparatus. Measurements were made with confining pressures ranging from 30 to 210 MPa and using argon pore fluid pressure of 20 MPa. Data show a variation of the permeability values of one order of magnitude between host rock and fault zone and a decrease of 50% of the elastic properties between host rock and core zone. The heterogeneity of properties is related to the development of different microstructures across the fault-zone during the tectonic history. From these physical property values and the fault zone architecture, we analyze the effects of sudden mechanical loading on the development of fluid overpressures in fault-zone. To do this, we use a series of 1-D hydromechanical numerical models to show that sudden mechanical stress increase is a viable mechanism for fluid overpressuring in fault-zone with spatially-varying elastic and hydraulic properties. Based on these results, we discuss the implications for earthquake triggering.on crustal-scale faults.

  10. Evaluation of space shuttle main engine fluid dynamic frequency response characteristics

    NASA Technical Reports Server (NTRS)

    Gardner, T. G.

    1980-01-01

    In order to determine the POGO stability characteristics of the space shuttle main engine liquid oxygen (LOX) system, the fluid dynamic frequency response functions between elements in the SSME LOX system was evaluated, both analytically and experimentally. For the experimental data evaluation, a software package was written for the Hewlett-Packard 5451C Fourier analyzer. The POGO analysis software is documented and consists of five separate segments. Each segment is stored on the 5451C disc as an individual program and performs its own unique function. Two separate data reduction methods, a signal calibration, coherence or pulser signal based frequency response function blanking, and automatic plotting features are included in the program. The 5451C allows variable parameter transfer from program to program. This feature is used to advantage and requires only minimal user interface during the data reduction process. Experimental results are included and compared with the analytical predictions in order to adjust the general model and arrive at a realistic simulation of the POGO characteristics.

  11. 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.

  12. Perspectives and Plans for Graduate Studies. 11. Engineering 1974. D. Mechanical Engineering. Report No. 74-21.

    ERIC Educational Resources Information Center

    Ontario Council on Graduate Studies, Toronto. Advisory Committee on Academic Planning.

    On the instruction of the Council of Ontario Universities, the Advisory Committee on Academic Planning in cooperation with the Committee of Ontario Deans of Engineering has conducted a planning assessment for doctoral work in mechanical engineering. This report presents as overview of the recommendations for each of the assessments conducted in…

  13. Adaptive implicit-explicit finite element algorithms for fluid mechanics problems

    NASA Technical Reports Server (NTRS)

    Tezduyar, T. E.; Liou, J.

    1988-01-01

    The adaptive implicit-explicit (AIE) approach is presented for the finite-element solution of various problems in computational fluid mechanics. In the AIE approach, the elements are dynamically (adaptively) arranged into differently treated groups. The differences in treatment could be based on considerations such as the cost efficiency, the type of spatial or temporal discretization employed, the choice of field equations, etc. Several numerical tests are performed to demonstrate that this approach can achieve substantial savings in CPU time and memory.

  14. AUTOMOTIVE DIESEL MAINTENANCE 1. UNIT VI, MAINTAINING MECHANICAL GOVERNORS--DETROIT DIESEL ENGINES.

    ERIC Educational Resources Information Center

    Human Engineering Inst., Cleveland, OH.

    THIS MODULE OF A 30-MODULE COURSE IS DESIGNED TO DEVELOP AN UNDERSTANDING OF THE OPERATION AND MAINTENANCE OF MECHANICAL GOVERNORS USED ON DIESEL ENGINES. TOPICS ARE (1) TYPES OF GOVERNORS AND ENGINE LOCATION, (2) GOVERNOR APPLICATIONS, (3) LIMITING SPEED MECHANICAL GOVERNOR, (4) VARIABLE SPEED MECHANICAL GOVERNOR, AND (5) CONSTANT SPEED…

  15. Automotive Engines; Automotive Mechanics I: 9043.03.

    ERIC Educational Resources Information Center

    Dade County Public Schools, Miami, FL.

    This automotive engines course studies and demonstrates the theory and principles of operation of the automotive four stroke cycle engine. The student will develop an understanding of the systems necessary to make the engine perform as designed, such as cooling, fuel, ignition and lubrication. This is a one or two quinmester credit course of 45…

  16. Regulation of amniotic fluid volume: mathematical model based on intramembranous transport mechanisms

    PubMed Central

    Anderson, Debra F.; Cheung, Cecilia Y.

    2014-01-01

    Experimentation in late-gestation fetal sheep has suggested that regulation of amniotic fluid (AF) volume occurs primarily by modulating the rate of intramembranous transport of water and solutes across the amnion into underlying fetal blood vessels. In order to gain insight into intramembranous transport mechanisms, we developed a computer model that allows simulation of experimentally measured changes in AF volume and composition over time. The model included fetal urine excretion and lung liquid secretion as inflows into the amniotic compartment plus fetal swallowing and intramembranous absorption as outflows. By using experimental flows and solute concentrations for urine, lung liquid, and swallowed fluid in combination with the passive and active transport mechanisms of the intramembranous pathway, we simulated AF responses to basal conditions, intra-amniotic fluid infusions, fetal intravascular infusions, urine replacement, and tracheoesophageal occlusion. The experimental data are consistent with four intramembranous transport mechanisms acting in concert: 1) an active unidirectional bulk transport of AF with all dissolved solutes out of AF into fetal blood presumably by vesicles; 2) passive bidirectional diffusion of solutes, such as sodium and chloride, between fetal blood and AF; 3) passive bidirectional water movement between AF and fetal blood; and 4) unidirectional transport of lactate into the AF. Further, only unidirectional bulk transport is dynamically regulated. The simulations also identified areas for future study: 1) identifying intramembranous stimulators and inhibitors, 2) determining the semipermeability characteristics of the intramembranous pathway, and 3) characterizing the vesicles that are the primary mediators of intramembranous transport. PMID:25186112

  17. 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.

  18. Actuation fluid adapter for hydraulically-actuated electronically-controlled fuel injector and engine using same

    DOEpatents

    Keyster, Eric S.; Merchant, Jack A.

    2002-01-01

    A fuel injector adapter consists of a block defining a pressure communication passage therethrough and an actuation fluid passage. The actuation fluid passage includes three separate branches that open through an outer surface of the block at three separate locations.

  19. Biennial Fluid Dynamics Symposium on Advanced Problems and Methods in Fluid Mechanics, 19th, Kozubnik, Poland, Sept. 3-8, 1989, Selected Papers

    NASA Astrophysics Data System (ADS)

    Recent advances in experimental and computational fluid mechanics are discussed in a series of review essays. Topics addressed include transitions to complex flow in thermal convection, optimum hypersonic wings and wave riders, relativistic hydrodynamics, and wind-tunnel wall corrections for unsteady flow (steady wall adaptation and CFD techniques). Consideration is given to axisymmetric laminar interacting boundary layers, differential forms and fluid dynamics, breaking water waves, strong temperature gradients in turbulent wakes, and liquid-crystal 'blue' phases.

  20. 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.

  1. Overview of heat transfer and fluid flow problem areas encountered in Stirling engine modeling

    NASA Technical Reports Server (NTRS)

    Tew, Roy C., Jr.

    1988-01-01

    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.

  2. Mechanical Design Engineering Enabler Project wheel and wheel drives

    NASA Technical Reports Server (NTRS)

    Nutt, Richard E.; Couch, Britt K.; Holley, John L., Jr.; Garris, Eric S.; Staut, Paul V.

    1992-01-01

    Our group was assigned the responsibility of designing the wheel and wheel drive system for a proof-of-concept model of the lunar-based ENABLER. ENABLER is a multi-purpose, six wheeled vehicle designed to lift and transport heavy objects associated with the construction of a lunar base. The resulting design was based on the performance criteria of the ENABLER. The drive system was designed to enable the vehicle to achieve a speed of 7 mph on a level surface, climb a 30 percent grade, and surpass a one meter high object and one meter wide crevice. The wheel assemblies were designed to support the entire weight of the vehicle on two wheels. The wheels were designed to serve as the main component of the vehicle's suspension and will provide suitable traction for lunar-type surfaces. The expected performance of the drive system for the ENABLER was influenced by many mechanical factors. The expected top speed on a level sandy surface is 4 mph instead of the desired 7 mph. This is due to a lack of necessary power at the wheels. The lack of power resulted from dimension considerations that allowed only an eight horsepower engine and also from mechanical inefficiencies of the hydraulic system. However, the vehicle will be able to climb a 30 percent grade, surpass a one meter high object and one meter wide crevice. The wheel assemblies will be able to support the entire weight of the vehicle on two wheels. The wheels will also provide adequate suspension for the vehicle and sufficient traction for lunar-type surfaces.

  3. Novel mechanically competent polysaccharide scaffolds for bone tissue engineering.

    PubMed

    Kumbar, S G; Toti, U S; Deng, M; James, R; Laurencin, C T; Aravamudhan, A; Harmon, M; Ramos, D M

    2011-12-01

    The success of the scaffold-based bone regeneration approach critically depends on the biomaterial's mechanical and biological properties. Cellulose and its derivatives are inherently associated with exceptional strength and biocompatibility due to their ?-glycosidic linkage and extensive hydrogen bonding. This polymer class has a long medical history as a dialysis membrane, wound care system and pharmaceutical excipient. Recently cellulose-based scaffolds have been developed and evaluated for a variety of tissue engineering applications. In general porous polysaccharide scaffolds in spite of many merits lack the necessary mechanical competence needed for load-bearing applications. The present study reports the fabrication and characterization of three-dimensional (3D) porous sintered microsphere scaffolds based on cellulose derivatives using a solvent/non-solvent sintering approach for load-bearing applications. These 3D scaffolds exhibited a compressive modulus and strength in the mid-range of human trabecular bone and underwent degradation resulting in a weight loss of 10-15% after 24 weeks. A typical stress-strain curve for these scaffolds showed an initial elastic region and a less-stiff post-yield region similar to that of native bone. Human osteoblasts cultured on these scaffolds showed progressive growth with time and maintained expression of osteoblast phenotype markers. Further, the elevated expression of alkaline phosphatase and mineralization at early time points as compared to heat-sintered poly(lactic acid-glycolic acid) control scaffolds with identical pore properties affirmed the advantages of polysaccharides and their potential for scaffold-based bone regeneration. PMID:22089383

  4. Chemo-mechanical effects of fluid invasion into low permeability rocks

    NASA Astrophysics Data System (ADS)

    Pagels, M.; Willberg, D.; Edelman, E.

    2011-12-01

    Exploitation of unconventional gas and oil reservoirs requires injection of large quantities of water-based fluids during hydraulic fracturing treatments. On average only 5 - 30 % of treatment fluids are recovered during flowback from these wells. The large quantity of residual treatment water remains either in the created fracture network, or imbibes into the rock matrix immediately surrounding the fracture network. As such this residual water is spatially located at the critical junction between the reservoir and the hydraulic fracture completion. Besides potentially causing the loss of relative permeability to hydrocarbons in the matrix rock surrounding the fracture, this residual water disrupts the chemical equilibrium of the rock, hydrocarbon and connate water system - leading to a physically and chemically altered zone of rock immediately adjacent to the fracture face. Loss of rock strength in the altered zone due to chemo-mechanical effects is a serious problem. Clearly it is important to understand the rate of fluid imbibition, the total quantity of fluid imbibed into the rock matrix, the depth of the altered rock zone adjacent to the fracture, and the loss of rock strength in this zone. A new laboratory method has been developed to quantitatively measure fluid leakoff and imbibition at the fracture face of ultra-low permeability unconventional reservoir rocks. Plugs taken from shale, mudstone, or ultra-low permeability carbonate reservoir cores are placed under confinement pressures and temperatures, simulating reservoir conditions. A low-flow rate imbibition/leakoff experiment is performed on the plug. The mechanisms of invasion are both pressure driven leak-off and imbibition. In the second stage of the experiment the core is dissected using a mechanical scratch tester. Leak-off into the pore structure of the matrix can be discriminated from artifacts such as leakoff into coring induced micro-fractures. The results show that fluid imbibition can be highly variable depending on the specific rock. Results are being correlated with the petrology of the rock. In addition to the quantitative determination of leak off and imbibition rates, the method measures the unconfined compressive strength (UCS) of the rock as a function of depth. Precise determination of the water content as a function of plug depth results in a water saturation profile throughout the plug and enables us to correlate rock strength, water saturation and exposure time. Experimental results show that imbibition and fluid loss into ultralow permeability shales, mudstones and carbonates can be substantial but are also highly variable depending on the texture and composition of the rock. The depth of water invasion in the experimental time frame of three days ranges from 0.5 to 3 cm in nanoDarcy permeability shales. The rock strength declines with exposure time to the fracturing fluid and correlates with the invading fluid saturation. Depending on the rock - softening due to fluid exposure can reduce the UCS by 25 - 50% over a 3 day exposure period. Loss of rock strength can lead to increased proppant embedment and a reduction in fracture conductivity. Increased embedment of proppant in turn can lead to fines generation due to displacement of rock matrix material with the risk of reducing proppant pack conductivity.

  5. Mechanical Engineering of the Linac for the Spallation Neutron Source

    SciTech Connect

    Bultman, N.K.; Chen, Z.; Collier, M.; Erickson, J.L.; Guthrie, A.; Hunter, W.T.; Ilg, T.; Meyer, R.K.; Snodgrass, N.L.

    1999-03-29

    The linac for the Spallation Neutron Source (SNS) Project will accelerate an average current of 1 mA of H{sup {minus}} ions from 20 MeV to 1GeV for injection into an accumulator ring. The linac will be an intense source of H{sup {minus}} ions and as such requires advanced design techniques to meet project technical goals as well as to minimize costs. The DTL, CCDTL and CCL are 466m long and operate at 805 MHz with a maximum H{sup {minus}} input current of 28 mA and 7% rf duty factor. The Drift Tube Linac is a copper-plated steel structure using permanent magnetic quadrupoles. The Coupled-Cavity portions are brazed copper structures and use electromagnetic quads. RF losses in the copper are 80 MW, with total rf power supplied by 52 klystrons. Additionally, the linac is to be upgraded to the 2- and 4-MW beam power levels with no increase in duty factor. The authors give an overview of the linac mechanical engineering effort and discuss the special challenges and status of the effort.

  6. Leak Mitigation in Mechanically Pumped Fluid Loops for Long Duration Space Missions

    NASA Technical Reports Server (NTRS)

    Miller, Jennifer R.; Birur, Gajanana; Bame, David; Mastropietro, A. J.; Bhandari, Pradeep; Lee, Darlene; Karlmann, Paul; Liu, Yuanming

    2013-01-01

    Mechanically pumped fluid loops (MPFLs) are increasingly considered for spacecraft thermal control. A concern for long duration space missions is the leak of fluid leading to performance degradation or potential loop failure. An understanding of leak rate through analysis, as well as destructive and non-destructive testing, provides a verifiable means to quantify leak rates. The system can be appropriately designed to maintain safe operating pressures and temperatures throughout the mission. Two MPFLs on the Mars Science Laboratory Spacecraft, launched November 26, 2011, maintain the temperature of sensitive electronics and science instruments within a -40 deg C to 50 deg C range during launch, cruise, and Mars surface operations. With over 100 meters of complex tubing, fittings, joints, flex lines, and pumps, the system must maintain a minimum pressure through all phases of the mission to provide appropriate performance. This paper describes the process of design, qualification, test, verification, and validation of the components and assemblies employed to minimize risks associated with excessive fluid leaks from pumped fluid loop systems.

  7. System and method for improving performance of a fluid sensor for an internal combustion engine

    DOEpatents

    Kubinski, David; Zawacki, Garry

    2009-03-03

    A system and method for improving sensor performance of an on-board vehicle sensor, such as an exhaust gas sensor, while sensing a predetermined substance in a fluid flowing through a pipe include a structure for extending into the pipe and having at least one inlet for receiving fluid flowing through the pipe and at least one outlet generally opposite the at least one inlet, wherein the structure redirects substantially all fluid flowing from the at least one inlet to the sensor to provide a representative sample of the fluid to the sensor before returning the fluid through the at least one outlet.

  8. Electrification of particulate entrained fluid flows-Mechanisms, applications, and numerical methodology

    NASA Astrophysics Data System (ADS)

    Wei, Wei; Gu, Zhaolin

    2015-10-01

    Particulates in natural and industrial flows have two basic forms: liquid (droplet) and solid (particle). Droplets would be charged in the presence of the applied electric field (e.g. electrospray). Similar to the droplet charging, particles can also be charged under the external electric field (e.g. electrostatic precipitator), while in the absence of external electric field, tribo-electrostatic charging is almost unavoidable in gas-solid two-phase flows due to the consecutive particle contacts (e.g. electrostatic in fluidized bed or wind-blown sand). The particle charging may be beneficial, or detrimental. Although electrostatics in particulate entrained fluid flow systems have been so widely used and concerned, the mechanisms of particulate charging are still lack of a thorough understanding. The motivation of this review is to explore a clear understanding of particulate charging and movement of charged particulate in two-phase flows, by summarizing the electrification mechanisms, physical models of particulate charging, and methods of charging/charged particulate entrained fluid flow simulations. Two effective methods can make droplets charged in industrial applications: corona charging and induction charging. The droplet charge to mass ratio by corona charging is more than induction discharge. The particle charging through collisions could be attributed to electron transfer, ion transfer, material transfer, and/or aqueous ion shift on particle surfaces. The charges on charged particulate surface can be measured, nevertheless, the charging process in nature or industry is difficult to monitor. The simulation method might build a bridge of investigating from the charging process to finally charged state on particulate surface in particulate entrained fluid flows. The methodology combining the interface tracking under the action of the applied electric with the fluid flow governing equations is applicable to the study of electrohydrodynamics problems. The charge distribution and mechanical behaviors of liquid surface can be predicted by using this method. The methodology combining particle charging model with Computational Fluid Dynamics (CFD) and Discrete element method (DEM) is applicable to study the particle charging/charged processes in gas-solid two phase flows, the influence factors of particle charging, such as gas-particle interaction, contact force, contact area, and various velocities, are described systematically. This review would explore a clear understanding of the particulate charging and provide theoretical references to control and utilize the charging/charged particulate entrained fluid system.

  9. Fluids in brittle faulting - what do earthquake source mechanisms tell us?

    NASA Astrophysics Data System (ADS)

    Fischer, Tomáå.¡; Guest, Alice

    2010-05-01

    The occurrence of crack opening became a focus of many recent seismological studies. While the crack opens, a tensional normal stress acts on the fault plane. Thus, the slip vector during the earthquake deviates from the fault surface. In terms of the seismological terminology, this is reported as the non-double-couple component. The crack opening is possible in extensional stress state only, which is characterized by a negative normal stress acting on the fault plane. Because negative stresses in large depths are improbable, the tensile components of earthquakes are usually explained by a high fluid pressure in the fault zone. However, despite frequent fluid involvement in source processes, only few source mechanisms studies show doubtless non-DC components of the moment tensors. This holds also for the microseismicity accompanying the hydraulic fracture stimulation of hydrocarbon and geothermal reservoirs. We join the typical seismological and geomechanical approaches in order to improve our understanding of the presence of crack opening in natural and injection induced earthquakes. We explain the relation of the shear and normal tractions on the fault plane to the occurrence of tensile events and show the reason for seldom occurrence of crack opening. Further we propose a method for assessing the fluid involvement in the fracture process using the focal mechanisms and apply it to a suitable data set of injection-induced seismicity.

  10. Fluid structural analysis of human cerebral aneurysm using their own wall mechanical properties.

    PubMed

    Valencia, Alvaro; Burdiles, Patricio; Ignat, Miguel; Mura, Jorge; Bravo, Eduardo; Rivera, Rodrigo; Sordo, Juan

    2013-01-01

    Computational Structural Dynamics (CSD) simulations, Computational Fluid Dynamics (CFD) simulation, and Fluid Structure Interaction (FSI) simulations were carried out in an anatomically realistic model of a saccular cerebral aneurysm with the objective of quantifying the effects of type of simulation on principal fluid and solid mechanics results. Eight CSD simulations, one CFD simulation, and four FSI simulations were made. The results allowed the study of the influence of the type of material elements in the solid, the aneurism's wall thickness, and the type of simulation on the modeling of a human cerebral aneurysm. The simulations use their own wall mechanical properties of the aneurysm. The more complex simulation was the FSI simulation completely coupled with hyperelastic Mooney-Rivlin material, normal internal pressure, and normal variable thickness. The FSI simulation coupled in one direction using hyperelastic Mooney-Rivlin material, normal internal pressure, and normal variable thickness is the one that presents the most similar results with respect to the more complex FSI simulation, requiring one-fourth of the calculation time. PMID:24151523

  11. Learning Activity Packets for Auto Mechanics II. Section A--Engine Rebuilding.

    ERIC Educational Resources Information Center

    Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    Eight learning activity packets (LAPs) are provided for the instructional area of engine rebuilding in the auto mechanics II program. They accompany an instructor's guide available separately. The LAPs outline the study activities and performance tasks for these eight units: (1) engine condition evaluation; (2) engine removal; (3) engine…

  12. Auto Mechanics I. Learning Activity Packets (LAPs). Section C--Engine.

    ERIC Educational Resources Information Center

    Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

    This document contains five learning activity packets (LAPs) that outline the study activities for the "engine" instructional area for an Auto Mechanics I course. The five LAPs cover the following topics: basic engine principles, cooling system, engine lubrication system, exhaust system, and fuel system. Each LAP contains a cover sheet that…

  13. First Microbial Community Assessment of Borehole Fluids from the Deep Underground Science and Engineering Laboratory (DUSEL)

    NASA Astrophysics Data System (ADS)

    Moser, D. P.; Anderson, C.; Bang, S.; Jones, T. L.; Boutt, D.; Kieft, T.; Sherwood Lollar, B.; Murdoch, L. C.; Pfiffner, S. M.; Bruckner, J.; Fisher, J. C.; Newburn, J.; Wheatley, A.; Onstott, T. C.

    2010-12-01

    Fluid and gas samples were collected from two flowing boreholes at the 4100 (1,250 m) and 4850 ft (1478 m) levels of the former Homestake Gold Mine in Lead, South Dakota. Service- and flood water samples were also collected as comparative benchmarks. With a maximum depth of 8,000 ft, (2,438 m), this mine currently hosts the Sanford Laboratory and is the proposed location for the US Deep Underground Science and Engineering Laboratory (DUSEL). The uncased 4100L hole is a legacy of mining; whereas, the cased 4850 hole was drilled in 2009 in support of large cavity construction. Both were packered or valved to exclude mine air and sampled anaerobically using aseptic technique. Physical measurements, aquatic and dissolved gas chemistry, cell counts, and microbial community assessments (SSU rRNA libraries) were performed on all samples. This study represents the first at Sanford Lab/DUSEL specifically focused on the deep biosphere rather than mine microbiology. Fluids from the two holes differed markedly, with that from 4100L being characterized by NaHCO3 and 4850 by Na2SO4. pH values of 8.2 vs. 7.5, conductivities (μS) of 1790 vs. 7667 and alkalinities (mg/L) of 767 vs. 187 were obtained from 4100L and 4850, respectively. As expected, the deeper 4850L hole had the higher temperature (38 vs. 30 oC). Neither had measureable nitrate, but both had similar dissolved organic C (DOC) concentrations (0.8 vs. 0.9 mg/L). Sulfate was present at 337 vs. 4,470 mg/L in 4100L and 4850L. Major dissolved gases were N2 (91 and 81 vol%), O2 (12 and 16 vol%) and CH4 (0.07 and 3.35 vol%) in 4100L and 4850L. The δ13C of CH4 was -51 and -56.7 permil in 4100L and 4850, respectively. The uncorrected 14C age of DIC was calculated at 25,310 (+/- 220) and 47,700 (+/-3,100) years for the two fluids. Cell counts were 5.9e3 and 2.01e5 in 4100L and 4850. Microbial community structure was diverse in both holes and distinct from that of service water. A large proportion of rRNA library clones were Proteobacteria and closely related to known or expected aerobes including: Thiobacillus, Siderooxidans, Leptothrix, Hydrogenophaga, Pseaudomonas, Methylomonas and Thiothrix, consistent with possible mine water or air contamination. Conversely, Deltaproteobacteria and Firmicute clones, often very closely related to others detected from deep mine or sediment habitats, suggests a deep subsurface component as well. Archaeal clones from 4100L were dominated by a deeply-branching clade with no cultivated representatives; whereas, those from 4850 were mostly related to known methanogens (e.g. Methanolobus). Collectively, this dataset suggests mixed end-member or deeply-sourced water partially overprinted by mine-related artifacts. However, until more is known concerning the deep hydrogeology of this system, it will be difficult to ascertain indigenous from impacted microbial communities in DUSEL.

  14. Testing of the Engineering Model Electrical Power Control Unit for the Fluids and Combustion Facility

    NASA Technical Reports Server (NTRS)

    Kimnach, Greg L.; Lebron, Ramon C.; Fox, David A.

    1999-01-01

    The John H. Glenn Research Center at Lewis Field (GRC) in Cleveland, OH and the Sundstrand Corporation in Rockford, IL have designed and developed an Engineering Model (EM) Electrical Power Control Unit (EPCU) for the Fluids Combustion Facility, (FCF) experiments to be flown on the International Space Station (ISS). The EPCU will be used as the power interface to the ISS power distribution system for the FCF's space experiments'test and telemetry hardware. Furthermore. it is proposed to be the common power interface for all experiments. The EPCU is a three kilowatt 12OVdc-to-28Vdc converter utilizing three independent Power Converter Units (PCUs), each rated at 1kWe (36Adc @ 28Vdc) which are paralleled and synchronized. Each converter may be fed from one of two ISS power channels. The 28Vdc loads are connected to the EPCU output via 48 solid-state and current-limiting switches, rated at 4Adc each. These switches may be paralleled to supply any given load up to the 108Adc normal operational limit of the paralleled converters. The EPCU was designed in this manner to maximize allocated-power utilization. to shed loads autonomously, to provide fault tolerance. and to provide a flexible power converter and control module to meet various ISS load demands. Tests of the EPCU in the Power Systems Facility testbed at GRC reveal that the overall converted-power efficiency, is approximately 89% with a nominal-input voltage of 12OVdc and a total load in the range of 4O% to 110% rated 28Vdc load. (The PCUs alone have an efficiency of approximately 94.5%). Furthermore, the EM unit passed all flight-qualification level (and beyond) vibration tests, passed ISS EMI (conducted, radiated. and susceptibility) requirements. successfully operated for extended periods in a thermal/vacuum chamber, was integrated with a proto-flight experiment and passed all stability and functional requirements.

  15. Induction of fiber alignment and mechanical anisotropy in tissue engineered menisci with mechanical anchoring.

    PubMed

    Puetzer, Jennifer L; Koo, Esther; Bonassar, Lawrence J

    2015-06-01

    This study investigated the effect of mechanical anchoring on the development of fiber organization and anisotropy in anatomically shaped tissue engineered menisci. Bovine meniscal fibrochondrocytes were mixed with collagen and injected into molds designed to produce meniscus implants with 12 mm extensions at each horn. After a day of static culture, 10 and 20mg/ml collagen menisci were either clamped or unclamped and cultured for up to 8 weeks. Clamped menisci were anchored in culture trays throughout culture to mimic the native meniscus horn attachment sites, restrict contraction circumferentially, and encourage circumferential alignment. Clamped menisci retained their size and shape, and by 8 weeks developed circumferential and radial fiber organization that resembled native meniscus. Clamping also increased collagen accumulation and improved mechanical properties compared to unclamped menisci. Enhanced organization in clamped menisci was further reflected in the development of anisotropic tensile properties, with 2-3 fold higher circumferential moduli compared to radial moduli, a similar ratio to native meniscus. Ten and 20mg/ml clamped menisci had similar levels of organization, with 20mg/ml menisci producing larger diameter fibers and significantly better mechanical properties. Collectively, these data demonstrate the benefit of using bio-inspired mechanical boundary conditions to drive the formation of a highly organized collagen fiber network. PMID:25770753

  16. Suppression mechanism of Kelvin-Helmholtz instability in compressible fluid flows

    NASA Astrophysics Data System (ADS)

    Karimi, Mona; Girimaji, Sharath S.

    2016-04-01

    The transformative influence of compressibility on the Kelvin-Helmholtz instability (KHI) at the interface between two fluid streams of different velocities is explicated. When the velocity difference is small (subsonic), shear effects dominate the interface flow dynamics causing monotonic roll-up of vorticity and mixing between the two streams leading to the KHI. We find that at supersonic speed differentials, compressibility forces the dominance of dilatational (acoustic) rather than shear dynamics at the interface. Within this dilatational interface layer, traveling pressure waves cause the velocity perturbations to become oscillatory. We demonstrate that the oscillatory fluid motion reverses vortex roll-up and segregates the two streams leading to KHI suppression. Analysis and illustrations of the compressibility-induced suppression mechanism are presented.

  17. Extrema principles of entrophy production and energy dissipation in fluid mechanics

    NASA Technical Reports Server (NTRS)

    Horne, W. Clifton; Karamcheti, Krishnamurty

    1988-01-01

    A survey is presented of several extrema principles of energy dissipation as applied to problems in fluid mechanics. An exact equation is derived for the dissipation function of a homogeneous, isotropic, Newtonian fluid, with terms associated with irreversible compression or expansion, wave radiation, and the square of the vorticity. By using entropy extrema principles, simple flows such as the incompressible channel flow and the cylindrical vortex are identified as minimal dissipative distributions. The principal notions of stability of parallel shear flows appears to be associated with a maximum dissipation condition. These different conditions are consistent with Prigogine's classification of thermodynamic states into categories of equilibrium, linear nonequilibrium, and nonlinear nonequilibrium thermodynamics; vortices and acoustic waves appear as examples of dissipative structures. The measurements of a typical periodic shear flow, the rectangular wall jet, show that direct measurements of the dissipative terms are possible.

  18. Extrema principles of entropy production and energy dissipation in fluid mechanics

    NASA Technical Reports Server (NTRS)

    Horne, W. Clifton; Karamcheti, Krishnamurty

    1988-01-01

    A survey is presented of several extrema principles of energy dissipation as applied to problems in fluid mechanics. An exact equation is derived for the dissipation function of a homogeneous, isotropic, Newtonian fluid, with terms associated with irreversible compression or expansion, wave radiation, and the square of the vorticity. By using entropy extrema principles, simple flows such as the incompressible channel flow and the cylindrical vortex are identified as minimal dissipative distributions. The principal notions of stability of parallel shear flows appear to be associated with a maximum dissipation condition. These different conditions are consistent with Prigogine's classification of thermodynamic states into categories of equilibrium, linear nonequilibrium, and nonlinear nonequilibrium thermodynamics; vortices and acoustic waves appear as examples of dissipative structures. The measurements of a typical periodic shear flow, the rectangular wall jet, show that direct measurements of the dissipative terms are possible.

  19. NASA GSFC Mechanical Engineering Latest Inputs for Verification Standards (GEVS) Updates

    NASA Technical Reports Server (NTRS)

    Kaufman, Daniel

    2003-01-01

    This viewgraph presentation provides information on quality control standards in mechanical engineering. The presentation addresses safety, structural loads, nonmetallic composite structural elements, bonded structural joints, externally induced shock, random vibration, acoustic tests, and mechanical function.

  20. Attack or attacked: the sensory and fluid mechanical constraints of copepods' predator-prey interactions.

    PubMed

    Kiørboe, Thomas

    2013-11-01

    Many animals are predator and prey at the same time. This dual position represents a fundamental dilemma because gathering food often leads to increased exposure to predators. The optimization of the tradeoff between eating and not being eaten depends strongly on the sensing, feeding, and mechanisms for mobility of the parties involved. Here, I describe the mechanisms of sensing, escaping predators, and capturing prey in marine pelagic copepods. I demonstrate that feeding tradeoffs vary with feeding mode, and I describe simple fluid mechanical models that are used to quantify these tradeoffs and review observations and experiments that support the assumptions and test the predictions. I conclude by presenting a mechanistically underpinned model that predicts optimal foraging behaviors and the resulting size-scaling and magnitude of copepods' clearance rates. PMID:23613321