Fluid Mechanics Research Research Articles

New hydraulics laboratory

The DeFrees Hydraulics Laboratory was opened in June 1984 as a 500‐m2 addition to the former hydraulics teaching laboratory in Cornell University's School of Civil and Environmental Engineering. Total laboratory space is now about 800 m2 and is dedicated to basic and applied research and teaching in hydraulics, fluid mechanics, and hydrology. Three major equipment installations are in progress: a 33‐m wave tank with a random wave generator for coastal/ocean engineering research, a 24‐m wind‐water tunnel for stratified flow and interfacial transfer research, and a 24‐m tilting flume for open channel turbulence and sediment transport research.

The Instrumentation of a Modern Fluid Mechanics Research Laboratory (Part 2)

The Instrumentation of a Modern Fluid Mechanics Research Laboratory (Part 2)

The Instrumentation of a Modern Fluid Mechanics Research Laboratory (Part 1)

The Instrumentation of a Modern Fluid Mechanics Research Laboratory (Part 1)

Contributions to the Theory of Single-Sample Uncertainty Analysis

Uncertainty Analysis is the prediction of the uncertainty interval which should be associated with an experimental result, based on observations of the scatter in the raw data used in calculating the result. In this paper, the process is discussed as it applies to single-sample experiments of the sort frequently conducted in research and development work. Single-sample uncertainty analysis has been in the engineering literature since Kline and McClintock's paper in 1953 [1] and has been widely, if sparsely, practiced since then. A few texts and references on engineering experimentation present the basic equations and discuss its importance in planning and evaluating experiments (see Schenck, for example [2]). Uncertainty analysis is frequently linked to the statistical treatment of the data, as in Holman [3], where it may be lost in the fog for many student engineers. More frequently, only the statistical aspects of data interpretation are taught, and uncertainty analysis is ignored. For whatever reasons, uncertainty analysis is not used as much as it should be in the planning, development, interpretation, and reporting of scientific experiments in heat transfer and fluid mechanics. There is a growing awareness of this deficiency among standards groups and funding agencies, and a growing determination to insist on a thorough description of experimental uncertainty in all technical work. Both the International Standards Organization [4] and the American Society of Mechanical Engineers [5] are developing standards for the description of uncertainties in fluid-flow measurements. The U. S. Air Force [6] and JANNAF [7] each have handbooks describing the appropriate procedures for their classes of problems. The International Committee on Weights and Measures (CIPM) is currently evaluating this issue [8]. The prior references, with the exception of Schenck and, to a lesser extent, Holman, treat uncertainty analysis mainly as a process for describing the uncertainty in an experiment, and end their discussion once that evaluation has been made. The present paper has a somewhat different goal: to show how uncertainty analysis can be used as an active tool in developing a good experiment, as well as reporting it. The concepts presented here were developed in connection with heat transfer and fluid mechanics research experiments of moderately large size (i.e., larger than a breadbox and smaller than a barn) and which may frequently require three

Laser Doppler velocimetry: A status report

Since the first experimental work in 1964, the measurement of velocity by means of the Doppler shift in scattered laser light has developed into an important tool in fluid mechanics research which often provides data unobtainable with other instruments. This paper reviews the fundamentals of laser Doppler velocimeter system design including optical requirements and signal processing considerations. Numerous applications are described to illustrate the present state of the art.

Review—Basic Research Needs in Fluid Mechanics

A small segment of the engineering community was surveyed to obtain their judgment regarding the long-range needs for basic research in fluid mechanics. This segment consisted of approximately 600 persons active in heat transfer and fluid mechanics committees within The American Society of Mechanical Engineers. Close to 200 persons responded giving useful information relating to needed research. Of the many topics identified, six generic areas stood out: turbulence; multiphase flows; fluid structure interactions; boundary layer effects; biological, geological, and environmental fluid flow; and the need for new facilities and improved instrumentation. These six areas were summarized and an initial estimate of the research priorities presented to the DOE-ESCOE workshop on Fluid Dynamics and Thermal Processes held at the University of Kentucky on February 1–2, 1979. The priorities were modified and the final results of the workshop included herein.

A glimpse of fluid mechanics research in Bangalore 25 years age

This paper gives a brief historical account of how fluid mechanics research began in the Aeronautical Engineering Department of the Indian Institute of Science. The motivation for the various investigations carried out in the 1950s and 1960s is recalled and some of the major results are summarized.

Fluid Mechanics Research in 1986

In 1965, a book was published with the title Research Frontiers in Fluid Dynamics, edited by Raymond Seeger and G. Temple. It was intended to give a panoramic view of some exciting vistas in fluid dynamics. It covered the following areas: (1) High-speed aerodynamics; (2) magnetophydrodynamics (MHD); (3) physics of fluids (low or high density, low or high temperature, etc); (4) constitutive properties of fluids (viscosity, viscoelasticity, etc.); (5) oceanography and meterology; (6) astrophysical and planetary fluid mechanics; and (7) mathematical aspects and numerical aspects. A few of these areas, such as MHD, have blossomed and faded away within a short decade. Some others, such as high-speed aerodynamics, have reached maturity and hope to keep their momentum. In the intervening years, we have witnessed that a number of fields in fluid mechanics have revived from their old times into a new life; still, some have emerged with brand new growth. For instance, the subject of long waves has had a colorful development, with the result of improving our understanding of at least seven different physical phenomena, though originally the solitary water wave was its home base. Low Reynolds number flows have again received new stimuli from many needed applications such as aerosol physics, two-phase flows, rheology, geophysics of the earth interior, as well as micro and molecular biology. Oil exploration has motivated various aspects of marine-related research and development, giving ever-increasing activities in ocean engineering. The energy program, a new glamorous field by its own importance, has brought forth investigations of fluid mechanical problems pertaining to nuclear, geothermal, solar, wind, ocean wave, and other forms of energy sources. Riding on the waves of these broad movements that have carried us thus far, we now hope to forecast the future of fluid mechanics research in 1986. We may like to put the focus at a slightly different depth and ask: What will be the most significant areas of fluid mechanics that by 1986 will enjoy the best prospects of vigorous development, most rewarding not only to the fluid dynamicist but also to mankind, and by then, still offer the expectation of longevity into the 1990's? The task is almost as hard as to make a prophecy on what the political world will be in 1986.

An Analysis of High-Velocity Gas Flow Through Porous Media

Darcy's law is inadequate for representing high-velocity gas flow in porous media, such as near the wellbore. An analysis of pressure lost during flow through conduits of alternating cross sections suggests more appropriate words for describing the mechanism for energy loss and terms in the flow equation. Updated correlations are presented for the coefficient of the velocity-squared term. Introduction Much research has been conducted to understand flow through porous media. Regarding high velocity, suitable correlations and nomenclature are the subject of controversy because of different views on the mechanism causing pressure drop. This study tries to improve the understanding of high-velocity flow through porous media. Using available data and this research, the best correlation is sought to permit the calculation of high-velocity flow based on permeability, porosity, and character of the rock. permeability, porosity, and character of the rock. We hope that a nomenclature can be suggested that is acceptable to both reservoir engineers and fluid mechanics research scientists. The results should be useful for improving correlations of gas-well flow data and for predicting well flow from core data, fluid properties, and specified conditions. properties, and specified conditions. Early Work on High-Velocity Flow Fancher et al. measured pressure drop during flow through a large number of unconsolidated and consolidated porous media. They correlated the data by using the porous media. They correlated the data by using the friction factor and Reynolds number, with grain diameter as a characteristic length. They showed that for flow through porous media, an increased pressure drop at high velocity is beyond that proportional to velocity. Data taken at the USBM were correlated using a quadratic equation of pressure drop with the second term of velocity to the nth power. Green and Duwez increased the understanding of high-velocity gas flow data when studying sintered metals. They adapted the equation with a velocity term squared that Forchheimer had developed: dp v- ---- = ----- + pv 2......................(1)dL k Comell and Katz measured the porosity, permeability, and B factors for cores, resulting in a correlation of B with permeability. The term B was called a "turbulence factor," but the expression was unacceptable to several researchers. Language Used in Literature Space limitations prohibit quoting completely the language used when describing the mechanism that consumes energy at more than a linear rate with velocity. The term used in flow equations (generally the in a quadratic flow equation) also has been given various names according to the author's view of the flow mechanism. Table 1 assembles selected typical titles and statements quoted from published works. After the flow mechanism has been reviewed, a more appropriate language will be submitted to agree with the concepts developed here. JPT P. 211

Duality in nonconvex optimization

We examine a notion of duality which appears to be useful in situations where the usual convex duality theory is not appropriate because the functional to be minimized is not convex. The principle is a generalization of a duality theorem derived previously (J. F. Toland, University of Essex Fluid Mechanics Research Institute, Report No. 77, November 1976, Arch. Rational Mech. Analysis (in press)), for nonconvex problems. The generalization is considerable, since no assumptions are made on the functional to be minimized, other than that it can be embedded in a family of perturbed problems. If such an embedding is possible, then the main theorem depends only on some rather well-known results in the theory of conjugate convex functions. We develop all the previously derived abstract results in this more general framework. The earlier work is seen to be a special case of this generalized duality theory. We treat abstract problems which are typical of those arising in the calculus of variations, and some applications are considered.

Potential Sluice Gate Flow With Generalized Boundaries

Technical Briefs Potential Sluice Gate Flow With Generalized Boundaries W. E. Conway W. E. Conway Fluid Mechanics Research Institute, University of Essex, England; Department of Mathematics, University of Arizona, Tucson, Ariz. Search for other works by this author on: This Site PubMed Google Scholar Author and Article Information W. E. Conway Fluid Mechanics Research Institute, University of Essex, England; Department of Mathematics, University of Arizona, Tucson, Ariz. J. Appl. Mech. Jun 1976, 43(2): 368-370 (3 pages) https://doi.org/10.1115/1.3423848 Published Online: June 1, 1976 Article history Received: May 1, 1975 Revised: November 1, 1975 Online: July 12, 2010

Development of a high-performance cryogenic shock tube

A cryogenic shock tube has been developed as a tool for research in fluid mechanics and low-temperature physics. The shock tube was designed to operate with the test section immersed in a cryogenic liquid. A unique diaphragm-changing mechanism makes this shock tube an economical and practical device. There are several advantages in operating a shock tube at cryogenic temperatures. Shock waves of very large Mach number can be produced. The flow field can be accurately calculated using ideal-shock-tube/perfect-gas theory. Boundary-layer effects are decreased, so that long test times are possible.The cases that were studied are test-gas temperatures of 300, 77, 4·2 and 2·3 °K. Helium was used as both test and driver gas. The largest Mach numbers observed range from 2·4 at 300 °K to 32 at 2·3 °K (several runs at 1·46 °K produced Mach 40 shocks). As the temperature of the test gas was decreased, the observed Mach numbers approached those calculated using the ‘shock-tube equation’.As a laboratory tool, the cryogenic shock tube may be applied in many areas and modified for use in even more. Shock waves with large Mach numbers and flows with large Reynolds numbers can be produced with this device. The rapid increase in temperature and pressure across the shock wave is useful for studies of sublimation, evaporation or chemical reactions. Quantum-mechanical effects in cryogenic materials, superconductors or superfluid helium can also be investigated.

Fluid Mechanics Teaching and Research: A View from a Dean's Office

Teaching and research in a field such as fluid mechanics must be administered by the dean to form an integral part of a many-membered curricular structure characterized by balance, coherence, and stability. The undergraduate aspects of the subject are inherently collegiate, and the graduate, properly departmental—whatever the basis for professional division. However, the civil engineering topics in fluid mechanics have their counterparts in most of the other professional fields, so that all stand to gain by generalization of approach.

Measurements of the viscometric functions for a fluid in steady shear flows

This paper describes a series of experiments in which the three material functions of steady viscometric flows were measured for a given polyisobutene solution. A number of instruments and measuring techniques were used in order to check the experimental method. The shear stress was determined from the torque transmitted by the fluid in a cone-and-plate apparatus and in Couette flow between concentric cylinders. The results obtained from these measurements were in good agreement with each other. The primary normal-stress difference was determined from the normal force acting on the plate of a cone-and-plate apparatus, and from stress-optical measurements on Couette flow between concentric cylinders. These results are in good agreement with each other. Detailed measurements of the distribution f Permanent address: Fluid Mechanics Research Institute, University of Essex, Colchester, Essex. of the normal stress acting on the plate of the cone-and-plate apparatus were made for three cone angles and for two boundary configurations at the rim of the apparatus: from these results a combination of the primary and the secondary normal-stress differences was deduced, thereby making possible the computation of the secondary normal-stress difference. When the normal stress acting on a rigid surface is measured by means of a hole leading to a pressure transducer the results are in error by an amount roughly proportional to the primary normal-stress difference of the fluid (cf. Kaye, Lodge & Vale 1968). In the present experiments this error was determined from measurements of the distribution of the normal stress acting on the plates of a plate-and-plate apparatus, together with the assumption that the error is a function only of the shear rate at the position o the hole in the undisturbed viscometric flow. The values of the measuring error thus obtained are in goo agreement with measurements made in Gouette flow between concentric cylinders. The secondary normal-stress difference, P2, was measured in a number of different ways. From the results it is suggested that the methods of Jackson & Kaye and of Marsh & Pearson may be imprecise and, in particular, may yield incorrect values for P2- A new, direct, method of estimating P2, suggested by Higashitani & Pritchard (1971) and outlined in appendix A, may provide a more convenient means of determining P2.

The National Bureau of Standards and its contributions to geophysics

Sixty‐five is a customary age of retirement. The National Bureau of Standards, however, celebrated its 65th year by moving from now outmoded quarters in Washington, D. C., to a magnificent new facility at Gaithersburg, Maryland. The new site, which was formally dedicated on November 15, 1966, consists of 15 major buildings on 565 acres in a rural environment (Figure 1). Included in the new complex are 7 general purpose laboratories, an 11‐story administration building, and special purpose buildings for a nuclear reactor, a linear accelerator, engineering mechanics, and shops. Yet to come are buildings for sound and fluid mechanics research, a hazards laboratory, a building for the study of concreting materials, and an industrial building.

The mechanics of non-Newtonian fluids: American research and research needs

The Economic Case for a Program in Non-Newtonian Fluid Mechanics Research. The mechanics of non-Newtonian materials dominates the technologies of production and utilization of the products of major segments of the chemical process industries. The magnitude of the current economic involvement is estimated at between 12 and 15 billion dollars for the U.S. alone. It is growing at a percentage rate which exceeds that of the overall chemicals and petroleum industries by afactor of 2 to 5 and the general economy's growth rate by a factor of 3 to 4. Clearly, this is a vital area of industrial endeavor.

Fluid Mechanics Research and Engineering Application in Non-Newtonian Fluid Systems

Abstract Fluid mechanics research conducted with non-Newtonian fluid systems now permits prediction of the behavior of these fluid systems in both laminar and turbulent modes of flow through circular pipes. Present work concerns non-Newtonian fluid systems currently used in the hydraulic fracturing process. During fracturing treatments, an unsteady-state condition may frequently be encountered arising from' the reaction rate of a chemical additive. This condition must be evaluated in order to predict the actual behavior of a particular fluid during field application. Design and operation of the apparatus used to determine fluid-flow behavior permit obtaining data under such non-equilibrium conditions. This paper shows methods used to obtain rheology measurements, develop hydraulic relationships and evaluate chemical reactions producing unsteady-state conditions. Engineering application of this research is illustrated by employing measured rheological values and developed hydraulic relationships to produce frictional pressure loss (psi/100 ft) vs flow rate (bbl/min) charts of common tubing and casing sizes for an example fracturing fluid. How these charts and chemical reaction rate information are then combined to predict actual turbulent hydraulic behavior during unsteady-state field conditions is also discussed. Introduction Many fluids used in hydraulic fracturing contain chemical additives which impart non-Newtonian fluid properties that may drastically alter their hydraulic behavior. Equally drastic alteration in wellhead pressure, injection rate and hydraulic horsepower requirement may result from these fluid properties. Prior research conducted to relate non-Newtonian fluid properties with hydraulic behavior has not as yet produced a universal relationship, particularly for the turbulent flow region. Which of the many possible non-Newtonian fluid properties is responsible has not been conclusively established. A systematic description, suggested by Metzner, of the many possible non-Newtonian fluid properties exhibited by real - fluid behavior, and a current discussion of theoretical and applied aspects of non-Newtonian fluid technology can be found in Handbook of Fluid Dynamics. Little or no research has previously been attempted with fluids exhibiting time - dependent properties. Addition of chemicals during a fracturing treatment is often accomplished by continuously mixing and displacing the fluid. This produces a time-dependent effect or unsteady-state condition while the fluid is progressing through surface and wellbore conductors. This condition is due to solution or chemical reaction of the additive. Considerable departure from conventional methods of obtaining and interpreting data was found necessary to consider these conditions. Therefore methods were developed to obtain hydraulic behavior information under these complex, unsteady-state conditions. Relationships presented in this paper to predict hydraulic behavior of non-Newtonian fluids in circular pipes were obtained by constructing and operating a small pipeline apparatus in the manner of a pilot-plant study. These relationships are suggested as scale-up equations and are not proposed as fundamental rheological parameters. While perhaps deficient from a fundamental research viewpoint, a pilot-plant study does permit the determination and convenient evaluation of variables pertinent to a process. A pilot-plant study can result in a valid engineering application procedure even when fundamental relationships are still undefined. An excellent series of articles by Bowen has appeared in the chemical engineering literature. These give a thorough review of proposed hydraulic relationships and their limitations for non-Newtonian fluid behavior in circular pipes. A graphical method is presented to scale up data for a fluid exhibiting an anomalous hydraulic behavior in the turbulent flow region. Considerable assistance has been obtained from these articles to interpret the anomalous behavior noted during this investigation. These articles also provided assurance that a pilot plant is a practical approach to evaluate the hydraulic behavior of non-Newtonian fracturing fluids. SPEJ P. 56ˆ

Twenty-Five Years More of Theoretical and Experimental Research in Fluid Mechanics

In the spring of 1914, in view of the tenth anniversary of the Aerodynamic Institute at Koutchino, near Moscow, I published a booklet in which I gave a survey of the Institute's activities since its foundation and concluded it as follows: “The problem of aerodynamical flying is solved, but, after the conquest of air space, another conquest, more difficult and of higher import, is offered to the ambition of man— the conquest of interplanetary spaces. “The brilliant progress of science gives hope that, in a more or less distant future, this problem will be solved in its turn through the patient and co-ordinated efforts of searchers impassioned by the greatness of this idea.“The brilliant progress of science gives hope that, in a more or less distant future, this problem will be solved in its turn through the patient and co-ordinated efforts of searchers impassioned by the greatness of this idea.

Application of the Electrical Analogy in Fluid Mechanics Research

The electrolytic bath and a modification thereof are presented as valuable tools in fundamental investigations of potential fluid flow. Principals and techniques are presented in full, together with some typical results which indicate the scope of the method and the accuracy obtainable. Particular emphasis is placed upon techniques which permit the high accuracy necessary in most studies.

Research in Fluid Mechanics

Research in Fluid Mechanics