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Showing papers on "Fluid dynamics published in 1972"


Journal ArticleDOI
TL;DR: In this article, the authors describe a theoretical investigation into the response of a spherical particle to a one-dimensional fluid flow, and the motion of the spherical particle in a uniform 2D fluid flow about a circular cylinder.
Abstract: This paper describes a theoretical investigation into (i) the response of a spherical particle to a one-dimensional fluid flow, (ii) the motion of a spherical particle in a uniform two-dimensional fluid flow about a circular cylinder and (iii) the motion of a particle about a lifting aerofoil section. In all three cases the drag of the particle is allowed to vary with (instantaneous) Reynolds number by using an analytical approximation to the standard experimental drag-Reynolds-number relationship for spherical particles.

2,401 citations


Journal ArticleDOI
25 Feb 1972-Science
TL;DR: The agreement between computed rates of decay and observed rates of aftershock activity suggests that this is an attractive mechanism for aftershockss.
Abstract: Large shallow earthquakes can induce changes in the fluid pore pressure that are comparable to stress drops on faults. The subsequent redistribution of pore pressure as a result of fluid flow slowly decreases the strength of rock and may result in delayed fracture. The agreement between computed rates of decay and observed rates of aftershock activity suggests that this is an attractive mechanism for aftershockss.

527 citations


Journal ArticleDOI
TL;DR: In this paper, a computing technique for low-speed fluid dynamics has been developed for the calculation of three-dimensional flows in the vicinity of one or more block-type structures, where the full time-dependent Navier-Stokes equations are solved with a finite-difference scheme based on the Marker-and-Cell method.

413 citations


Book
01 Jan 1972

259 citations


Journal ArticleDOI
TL;DR: A hot-film anemometer system, modified for use within arteries, has been used to examine flow disturbances in the aorta, and results suggested that the extent of flow-disturbances may be influenced by both peak flow velocity and pulse-rate.
Abstract: The general nature of flow-disturbances and turbulence in fluid flows, and the special features which may govern their appearance in unsteady flows, are considered. A hot-film anemometer system, modified for use within arteries, has been used to examine flow disturbances in the aorta. Results suggested that the extent of flow-disturbances may be influenced by both peak flow velocity and pulse-rate, expressed in terms of the relevant fluid dynamic parameters. Possible underlying mechanisms are discussed, and power spectra for laminar and highly disturbed aortic velocity waveforms presented.

170 citations


Book
01 Jan 1972
TL;DR: In this article, the International System of Units (SI) is used to measure the relationship between pressure and energy consumption, and the International Journal of Distributed Sensor Networks (ILSN) is also used for measuring energy consumption.
Abstract: (NOTE: Most chapters begins with The Big Picture and Objectives and concludes with References, Internet Sites, Practice Problems, and Computer Programming Assignments sections) 1 The Nature of Fluids and the Study of Fluid Mechanics Basic Introductory Concepts The International System of Units (SI) The US Customary System Weight and Mass Temperature Consistent Units in an Equation The Definition of Pressure Compressibility Density, Specific Weight, and Specific Gravity Surface Tension 2 Viscosity of Fluids Dynamic Viscosity Kinematic Viscosity Newtonian Fluids and Nonnewtonian Fluids Variation of Viscosity with Temperature Viscosity Measurement SAE Viscosity Grades ISO Viscosity Grades Hydraulic Fluids for Fluid Power Systems 3 Pressure Measurement Absolute and Gage Pressure Relationship Between Pressure and Elevation Development of the Pressure-Elevation Relation Pascal's Paradox Manometers Barometers Pressure Expressed as the Height of a Column of Liquid Pressure Gages and Transducers 4 Forces Due to Static Fluids Gases Under Pressure Horizontal Flat Surfaces Under Liquids Rectangular Walls Submerged Plane Areas-General Development of the General Procedure for Forces on Submerged Plane Areas Piezometric Head Distribution of Force on a Submerged Curved Surface Effect of a Pressure Above the Fluid Surface Forces on a Curved Surface with Fluid Below It Forces on Curved Surfaces with Fluid Above and Below 5 Buoyancy and Stability Buoyancy Buoyancy Materials Stability of Completely Submerged Bodies Stability of Floating Bodies Degree of Stability 6 Flow of Fluids and Bernoulli's Equation Fluid Flow Rate and the Continuity Equation Commercially Available Pipe and Tubing Recommended Velocity of Flow in Pipe and Tubing Conservation of Energy-Bernoulli's Equation Interpretation of Bernoulli's Equation Restrictions on Bernoulli's Equation Applications of Bernoulli's Equation Torricelli's Theorem Flow Due to a Falling Head 7 General Energy Equation Energy Losses and Additions Nomenclature of Energy Losses sand Additions General Energy Equation Power Required by Pumps Power Delivered to Fluid Motors 8 Reynolds Number, Laminar Flow, Turbulent Flow, and Energy Losses Due to Friction Reynolds Number Critical Reynolds Numbers Darcy's Equation Friction Lass in Laminar Flow Friction Loss in Turbulent Flow Equations for Friction Factor Hazen-Williams Formula for Water Flow Other Forms of the Hazen-Williams Formula Nomograph for Solving Hazen-Williams Formula 9 Velocity Profiles for Circular Sections and Flow in Noncircular Sections Velocity Profiles Velocity Profile for Laminar Flow Velocity Profile for Turbulent Flow Flow in Noncircular Sections 10 Minor Losses Resistance Coefficient Sudden Enlargement Exit Loss Gradual Enlargement Sudden Contraction Gradual Contraction Entrance Loss Resistance Coefficients for Valves and Fittings Application of Standard Valves Pipe Bends Pressure Drop in Fluid Power Valves Flow Coefficients for Valves Using Cv Plastic Valves 11 Series Pipe Line Systems Class I Systems Spreadsheet Aid for Class I Problems Class II Systems Class III Systems Pipeline Design for Structural Integrity 12 Parallel Pipe Line Systems Systems with Two Branches Systems with Three or More Branches-Networks 13 Pump Selection and Application Parameters Involved in Pump Selection Types of Pumps Positive Displacement Pumps Kinetic Pumps Performance Data for Centrifugal Pumps Affinity Laws for Centrifugal Pumps Manufacturer's Data for Centrifugal Pumps The Operating Point of a Pump and Pump Selection Net Positive Suction Head Suction Line Details Discharge Line Details Piping System Design and Pump Selection Procedure Alternate System Operating Modes Pump Selection and Specific Speed Life Cycle Costs for Pumped Fluid System Software for Piping System Design and Pump Selection 14 Open Channel Flow Classification of Open Channel Flow Hydraulic Radius and Reynolds Number in Open Channel Flow Kinds of Open Channel Flow Uniform Steady Flow in Open Channels The Geometry of Typical Open Channels The Most Efficient Shapes for Open Channels Critical Flow and Specific Energy Hydraulic Jump Open Channel Flow Measurement 15 Flow Measurement Flowmeter Selection Factors Variable Head Meters Variable Area Meters Turbine Flowmeter Vortex Flowmeter Magnetic Flowmeter Ultrasonic Flowmeters Positive Displacement Meters Mass Flow Measurement Velocity Probes Level Measurement Computer-Based Data Acquisition and Processing 16 Forces Due to Fluids in Motion Force Equation Impulse-Momentum Equation Problem-Solving Method Using the Force Equations Forces on Stationary Objects Forces on Bends in Pipe Lines Forces on Moving Objects 17 Drag and Lift Drag Force Equation Pressure Drag Drag Coefficient Friction Drag on Spheres in Laminar Flow Vehicle Drag Compressibility Effects and Cavitation Lift and Drag on Airfoils 18 Fans, Blowers, Compressors, And The Flow Of Gases Gas Flow Rates and Pressures Classification of Fans, Blowers, and Compressors Flow of Compressed Air and Other Gases in Pipes Flow of Air and Other Gases through Nozzles 19 Flow Of Air In Ducts Energy Losses in Ducts Duct Design Energy Efficiency and Practical Consideration in Duct Design Appendixes Properties of Water Properties of Common Liquids Typical Properties of Petroleum Lubricating Oils Variation of Viscosity with Temperature Properties of Air Dimensions of Steel Pipe Dimensions of Steel Tubing Dimensions of Type K Copper Tubing Dimensions of Ductile Iron Pipe Areas of Circles Conversion Factors Properties of Areas Properties of Solids Gas Constant, Adiabatic Exponent, and Critical Pressure Ratio for Selected Gases Answers to Selected Problems Index

164 citations


Journal ArticleDOI
TL;DR: In this paper, the application of fluid dynamics to layered systems with one or several flexible boundaries affected by gravity is reviewed and theoretical equations are verified from models studied by the finite element method and by experimental tests with liquid models.

131 citations



Journal Article
TL;DR: In this paper, integral and transport differential equations are discussed as aids in analyzing turbulence in fluid dynamics studies and the mechanism of turbulence and physics of shear layers are evaluated as preliminary steps, and typical calculation methods for turbulence models presented.
Abstract: Mathematical methods, such as integral and transport differential equations, are discussed as aids in analyzing turbulence in fluid dynamics studies. The mechanism of turbulence and physics of shear layers are evaluated as preliminary steps, and typical calculation methods for turbulence models presented.

115 citations


Journal ArticleDOI
TL;DR: In this article, it was shown that G(t) contains an inertial term which depends on the velocity distribution in the liquid surrounding the particle, and the results obtained lead to the correct value of the diffusivity.
Abstract: From Boussinesq's work it is known that the frictional resistance of a particle in a viscous, inert fluid, depends on its history. This plays an important part in Brownian motion. The general theory of fluctuations in fluid dynamics leads to explicit expressions for the autocorrelation function G(t) for the random force acting on a Brownian particle and the autocorrelation function φ(t) for its velocity. It is demonstrated that G(t) contains an inertial term which depends on the velocity distribution in the liquid surrounding the particle. The results obtained lead to the correct value of the diffusivity.

101 citations


Journal ArticleDOI
TL;DR: In this article, a relation for the grain dispersive pressure is solved together with the momentum equation of fluid flow, utilizing an empirical relation for apparent viscosity of the phenocryst suspension.
Abstract: Mechanical interactions between phenocrysts during magma flow give rise to a grain-dispersive pressure. During intrusion into a dike or sill, in the absence of forces other than those of grain interaction, the grain-dispersive pressure must be constant across the flow width. As a result, the concentration of phenocrysts must decrease toward the walls to offset the increase in the velocity gradient as the walls are approached. This mechanism has been offered as an explanation for the observed rapid but gradational increases in content from phenocryst-poor margins to a phenocryst-rich center, especially in picritic dikes and sills. A relation for the grain dispersive pressure is solved together with the momentum equation of fluid flow, utilizing an empirical relation for the apparent viscosity of the phenocryst suspension. Solutions for steady flow between parallel walls demonstrate pluglike velocity profiles as well as phenocryst-concentration increases toward the center away from the walls. The velocity is nearly the maximum value within the central half of the flow. Therefore very strong pseudoplastic non-Newtonian behavior of the magma need not be assumed to explain the observed phenocryst concentration variations.

Journal ArticleDOI
TL;DR: In this paper, a continuum theory of nonlocal fluid dynamics is proposed and the balance laws, jump conditions and the constitutive equations are obtained generalizing classical stokesian fluids to include the nonlocal effects.


Journal ArticleDOI
TL;DR: In this article, the energy and adsorbate conservation equations for continuous changes of state are transformed to characteristic form, and recognized to be two kinematic wave equations, each describing the propagation of a small change in a combined potential depending on temperature and adorbate concentration.

Journal ArticleDOI
TL;DR: In this article, the authors investigated the flow and heat transfer around two cylinders in cross flow (one of them in the wake of the other) and determined the distribution of the static pressure coefficients and Nusselt number on the surfaces of both cylinders by measurements.

Journal ArticleDOI
TL;DR: In this paper, asymptotic expansion techniques are used in the limit of large Reynolds number, to study the structure of fully turbulent shear layers, and closure is effected through the introduction of an eddy viscosity model formulated with sufficient generality so that most existing models are special cases.
Abstract: : Asymptotic expansion techniques are used in the limit of large Reynolds number, to study the structure of fully turbulent shear layers. Two cases examined are channel (or pipe) flow and two-dimensional boundary layer flow with an applied pressure gradient, upstream of any separation. Attention, for these two cases, is confined to the flow of incompressible constant-property fluids. Closure is effected through the introduction of an eddy viscosity model formulated with sufficient generality so that most existing models are special cases.

Journal ArticleDOI
TL;DR: In this article, the authors used psychrometric charts to predict the behavior of a silica-gel air-drier operating under equilibrium conditions, and compared these charts with published measurements taken from a real system.

Journal ArticleDOI
K.V. Roberts1, J.P. Christiansen1
TL;DR: In this paper, a brief survey is given of some of the many different types of flow that can occur, indicating how the analytic and numerical techniques that are found to be most appropriate in practice can be related to particular physical characteristics of the problem in hand.

Journal ArticleDOI
TL;DR: In this article, a finite difference numerical solution for the problem of thermal convection in a square enclosure is discussed for Prandtl numbers varying from 0.0127 (liquid tin) to 10.0 (water).

Journal ArticleDOI
TL;DR: The theory of concentrated two-phase mixtures developed in the previous parts of this paper is applied to analysis of the structure of the local random motion (pseudo-turbulence) occurring in flows of suspensions of small solid spheres as mentioned in this paper.
Abstract: The theory of concentrated two-phase mixtures developed in the previous parts of this paper is applied to analysis of the structure of the local random motion (pseudo-turbulence) occurring in flows of suspensions of small solid spheres. Suspensions under study are assumed to be locally homogeneous in the sense that large-scale agglomerates of many particles or voids filled with the pure liquid do not arise in their flows and particles can be approximately regarded as statistically independent units. Coefficients of the particle diffusion caused by pseudo-turbulence are calculated without restrictions imposed on the value of the Reynolds number Re characterizing the fluid flow around one particle. Other pseudo-turbulent quantities (the r.m.s. pseudo-turbulent velocities of both phases, their effective pseudo-turbulent viscosities in a shear flow, etc.) are considered for small Re. In particular, a natural explanation is given to the known effect of the reduced hydraulic resistance of a fluidized bed as compared with that of a stationary particulate bed of the same porosity. Additionally, some properties of the mean motion of a suspension influenced by pseudo-turbulence are discussed brifly. By way of example, two problems are considered: stability of the upward flow of a homogeneous suspension with respect to small perturbations depending upon the vertical co-ordinate and time, and the spatial distribution of particles suspended by the upward flow of a fluid under gravity.

Proceedings ArticleDOI
01 Jan 1972
TL;DR: In this paper, the steady-state flow of aqueous foam in circular pipes was formulated from laboratory and pilot-scale experimental data and incorporated into a mathematical model of foam circulation in oil wells.
Abstract: Equations for steady-state flow of aqueous foam in circular pipes were formulated from laboratory and pilot-scale experimental data. These equations were incorporated into a mathematical model of foam circulation in oil wells. The model was tested in 2 oil wells, and predictions were satisfactory for engineering calculations. Accuracy of the model may be increased further by accounting for liquid holdup during foam circulation in large-diameter wells. (18 refs.)

Journal ArticleDOI
TL;DR: In this paper, the critical flow velocity at which the pipe loses stability has been computed for four end conditions, and it is shown that when the flow velocity exceeds a certain value, the conservative system becomes subject to buckling-type instability and the non-conservative system becoming subject to fluttering-type and buckling type instabilities.

Journal ArticleDOI
TL;DR: In this paper, the authors modeled natural convection in a porous medium by writing force mass and energy balances on a differential element of porous medium and solved numerically after the introduction of a pseudo-stream function.
Abstract: Natural convection in a porous medium was mathematically modelled by writing force mass and energy balances on a differential element of porous medium. The resultant set of partial differential equations, which accounts for temperature-dependent physical properties, was solved numerically after the introduction of a pseudo-stream function. This method of treating emperature-dependent fluid properties, which is also applicable to other fluid flow problems, resulted in an efficient solution algorithm. Good agreement has been obtained between theoretical and experimental results. Theoretical calculations show that under certain conditions variation of fluid properties with temperature has a significant effect on convective motions.

Journal ArticleDOI
TL;DR: In this article, the vibration of a flexible elastic plate is investigated by a Monte Carlo technique and the response analysis is performed in time domain by numerically simulating the resulting generalized forces.
Abstract: The vibration of a flexible elastic plate is investigated by a Monte Carlo technique. The response analysis is performed in time domain by numerically simulating the resulting generalized forces. The nonlinear plate deflection and mutual interaction between the plate motion and external and/or internal airflow is included. The fluid perturbations due to the structural motion are described by linear aerodynamic theory. The boundary-layer pressure field is idealized as a homogeneous multidimensional Gaussian random process with mean zero. The plate differential equations of motion and boundary conditions are satisfied in a Galerkin sense by developing a modal solution. Illustrative examples are presented for subsonic and supersonic flow regions using shallow cavity and two plate mode approximations.


Patent
10 Mar 1972
TL;DR: In this paper, a fluid flow metering method and system using digital signals and logic for producing a compensated manifestation of fluid flow by the mathematical multiplication of two or more sensed parameters, one parameter being the fluid flow rate and the other one or more parameters being related to a condition of the fluid such as its constituency, pressure, density, dielectric constant, temperature or the like.
Abstract: A fluid flow metering method and system using digital signals and logic for producing a compensated manifestation of fluid flow by the mathematical multiplication of two or more sensed parameters, one parameter being a fluid flow rate and the other one or more parameters being related to a condition of the fluid such as its constituency, pressure, density, dielectric constant, temperature or the like, where the parameters are represented by series of electrical pulses The digital output signal pulses of the flowmeter are related to fluid flow, and are used to gate packets of high frequency pulses from a transducer The duration of the pulse packet is designed to be less than spacing between two adjacent flow pulses at maximum flow rate, and the exact number of high frequency pulses in each packet is related to the condition of the fluid as sensed by the transducer In one embodiment, the duration of the packet is a function of time in which case the pulses in the packet may be gated from a continuous series of high frequency pulses having a frequency related to the condition of the fluid The flow pulses recorded in a first counter provide a manifestation of gross fluid flow The pulses from the packets recorded in a second counter provide manifestation of compensated fluid flow Subtraction of the pulse trains through suitable scalers can yield a manifestation directly related to the compensated fluid flow in the same units as are used in providing gross fluid flow A transducer output linearizing circuit and a flowmeter bearing friction compensating circuit may optionally be incorporated in the described system

Journal ArticleDOI
01 May 1972-Wear
TL;DR: In this paper, the authors examined the nature of and necessary conditions for pneumatic tire hydroplaning and analyzed the fluid flow in terms of the mean quantities over the film thickness.

Journal ArticleDOI
TL;DR: In this paper, a new integral method is devised to predict the behavior of buoyant jets discharged to infinite, flowing, stratified ambients through single submerged diffusers, based on an integration of the basic partial differential equations written in a natural coordinate system.
Abstract: A new integral method is devised to predict the hydrothermal behavior of buoyant jets discharged to infinite, flowing, stratified ambients through single submerged diffusers. The method, based on an integration of the basic partial differential equations written in a natural coordinate system, is more general than previous methods. In addition, a new generalized entrainment function is defined which includes the effects of internal turbulence, buoyancy, jet orientation, and cross flow. Only one of the four entrainment coefficients is obtained by fitting predictions to data. Theoretical predictions are compared with 29 different flows. Agreement between theory and data is good; this is particularly significant as the range in experimental flow variables is considerable and the four entrainment coefficients are maintained constant for all predictions.

Patent
05 May 1972
TL;DR: An ultrasonic fluid flow metering system for use in monitoring volumetric flow of fluids conveyed in conduits or open channels is described in this paper, where pulses are applied to the transducers and the transit time of the pulse energy through the fluid in two directions is utilized to generate frequencies which give an indication of the fluid flow.
Abstract: An ultrasonic fluid flow metering system for use in monitoring volumetric flow of fluids conveyed in conduits or open channels. The flow meter includes at least one pair of transducers which alternately operate as transmitters and receivers to propagate energy through the flowing medium between the transducers. Pulses are applied to the transducers and the transit time of the pulse energy through the fluid in the two directions is utilized to generate frequencies which give an indication of the fluid flow. The system includes means for generating pulses which are transmitted through the fluid in opposite directions and a voltage controlled oscillator, the output of which is divided and used to provide delayed output pulses. The delayed output pulses are compared in time phase to the received pulses transmitted through the fluid in the conduit or channel and the frequency of the oscillator is controlled to provide time coincidence between the compared pulses. A count of the VCO output pulses over a predetermined period is alternately performed for upstream and downstream transmissions and the difference in the count provides a measure of the fluid flow.

Journal ArticleDOI
TL;DR: In this paper, the theoretical performance of an HF diffusion-type chemical laser is investigated by means of exact numerical solutions for the laminar diffusion of a finite stream of H2 into a semi-infinite stream containing F and a diluent in the presence of an incident coherent radiation field.
Abstract: : The theoretical performance of an HF diffusion-type chemical laser is investigated by means of exact numerical solutions for the laminar diffusion of a finite stream of H2 into a semi-infinite stream containing F and a diluent in the presence of an incident coherent radiation field. This flow model corresponds to flow in a single semichannel of a diffusion-type chemical laser. The initial flow velocity, temperature, and hydrogen stream thickness is held constant, and the effect of pressure level, initial fluorine partial pressure, and incident radiation intensity on peak integrated gain, axial extent of the lasing region, laser output power, and chemical efficiency is investigated.