Begell House Inc.
International Journal of Fluid Mechanics Research
FMR
2152-5102
30
1
2003
Investigation of Forsed Convection in an Almost Circular Microtube with Rough Walls
10
10.1615/InterJFluidMechRes.v30.i1.10
D. A.
Nield
Department of Engineering Science, University of Auckland, Auckland, New Zealand
Andrey V.
Kuznetsov
Department of Mechanical and Aerospace Engineering, North Carolina State University, Campus Box 7910, Raleigh, NC 27695, USA
Steady laminar flow of an incompressible fluid through a tube of almost circular cross-section is examined analytically, first for the case of a tube whose wall is wavy in the azimuthal direction, and then for one wavy in the axial direction. For the first case, a complete solution of the flow and forced convection heat transfer (for constant flux at the boundary) is possible for a wall of arbitrary cross-section. It is shown that, for a fixed axial pressure gradient, any departure from circularity leads to a reduction in volume flux and a reduction in heat transfer. For the second case no simple analytic solution is possible, but estimates of the increase in resistance due to a departure from circularity have been made.
Reconstruction of Ocean Density Distribution from its Wave Spectrum
13
10.1615/InterJFluidMechRes.v30.i1.20
L. V.
Cherkesov
Marine Hydrophysical Institute of National Academy of Sciences of Ukraine, Sevastopol, Ukraine
E. N.
Potetunko
Rostov State University, Rostov-on-Don, Russia
D. S.
Shubin
Rostov State University, Rostov-on-Don, Russia
A methods for the solution of the "inverse problem", i. e., the problem of reconstruction of the ocean stratification data on the basis of the known dispersion equations and the dispersion curves for the internal gravity waves, is suggested in the paper. Setting the values of the vibration frequencies and wave numbers with different degree of accuracy and simulating the character of stratification within the piecewise-linear approximation, we show the accuracy with which the reconstruction is possible and establish the limits of sensitivity for the measuring equipment.
Theoretical Analysis of the Schemes of Control over a Near-Wall Flow by Means of Interceptors
13
10.1615/InterJFluidMechRes.v30.i1.30
V. O.
Gorban
Institute of Hydromechanics of National Academy of Sciences of Ukraine, Kyiv, Ukraine
I. M.
Gorban
Institute of Hydromechanics of National Academy of Sciences of Ukraine, Kyiv, Ukraine
Within the limits of a plane problem, the paper addresses the possibility of formation of large-scale steady vortices in a flow around ledges (interceptors). The model of ideal incompressible fluid is employed. The solutions are constructed by the method of discrete vortices. The dependencies for an intensity of the steady vortex, its coordinates and eigenfrequencies on the angle of inclination of the interceptor are obtained. It is demonstrated that, through the suction of fluid behind the interceptor, extents of the separation domain can be decreased and the corresponding circulation zones can be stabilized. The dependencies are obtained for the suction intensity which provides the localization of the separation and the stability of the corresponding circulation zones in the cases of one, two or a set of the interceptors.
Parametric Vibrations of Three-Layer Piezoelectric Shells of Revolution
19
10.1615/InterJFluidMechRes.v30.i1.40
O. V.
Karnaukhova
S.P.Timoshenko Institute of Mechanics of National Academy of Sciences of Ukraine, Kyiv, Ukraine
V. I.
Kozlov
S.P.Timoshenko Institute of Mechanics of National Academy of Sciences of Ukraine, Kyiv, Ukraine
A. O.
Rasskazov
S.P.Timoshenko Institute of Mechanics of National Academy of Sciences of Ukraine, Kyiv, Ukraine
The problem of parametric vibrations of elastic three-layer shells composed of middle orthotropic dielectric or metal layer and two piezoelectric layers is studied. On the basis of the mechanical Kirchoff - Love hypothesis and adequate assumptions for an electrical field the constitutive equations for forces and moments are obtained for varying electrode positions, type of polarization and electrical boundary conditions. It is shown how nonlinear and linearized equations describing the parametric vibrations of the arbitrary shaped shells can be obtained if the constitutive equations, universal equations of motion, kinematic equations and boundary conditions are used. The linearized equations describe a region of dynamic instability (RDI). On the boundary of RDI the harmonic motion occurs. This gives an opportunity to reduce the problem of investigations of the principal RDI to solving the eigenvalue problems and the problem of static stability. Method of finite elements is developed to solve these problems. The problem of parametric vibrations of a three-layer cylindrical piezoelectric panel is considered in detail. The analytical solution of the problem is obtained for the case of simply supported edges. Correlation of an analytical and finite-element solutions demonstrates high accuracy of the first. The problem of parametric vibrations under harmonic mechanical load is solved for the open-circuited and short-circuited conditions. The essential influence of the electric boundary conditions on the size of RDI that can be used for control of the parametric vibrations of the shells is shown. The finite-element solution of the problem of parametric vibrations of cylindrical piezoelectric panel with clamped edges is obtained. The numerical results point to essential influence of mechanical boundary conditions on the size and position of RDI.
Complex Influence of Compliance of a Surface and High-Molecular Polymer Additives on Turbulent Friction
8
10.1615/InterJFluidMechRes.v30.i1.50
V. I.
Korobov
Institute of Hydromechanics of National Academy of Sciences of Ukraine, Kyiv, Ukraine
The turbulent friction over a rigid cylinder or a cylinder with an elastic cover, which is flowed around in the longitudinal direction, is studied experimentally at the Reynolds number within the range 106 - 2 Ч 107 in the case when aqueous solution of a polyoxyethylene is injected into the near-wall domain through a fore slot. For analogues of the hydrobionts' integuments, the hydrodynamic efficiency was higher under the complex influence, as compared to action of separate factors.
Some Adaptive Structural-Functional Characteristics of Fish Epidermis and its Derivatives
10
10.1615/InterJFluidMechRes.v30.i1.60
A. P.
Koval'
I. I. Shmalgauzen Institute of Zoology of National Academy of Sciences of Ukraine, Kyiv, Ukraine
A structure and adaptive features of epidermis of various fishes are analyzed in the paper. We consider the ways of excretion of mucus onto the body's surface, the action of it on the flow regime and the influence of both a body's shape and a speed of swimming on the topography of the secretory system. The mucus-producing function of the epidermis is shown to be determined by both the ecology surrounding a fish and the speed of swimming rather than by the stage of development of the scales.
Relationship between Probabilistic and Spatial-Time Mean Values for Turbulent Suspension Flow
14
10.1615/InterJFluidMechRes.v30.i1.70
S. I.
Kril'
Institute of Hydromechanics of National Academy of Sciences of Ukraine, Kyiv, Ukraine
V. P.
Berman
Institute of Hydromechanics of National Academy of Sciences of Ukraine, Kyiv, Ukraine
A partial differential equation relating to the probability-averaged mean value to the spatial-time-averaged one for the nonuniform stationary field of an averaged hydrodynamic quantity of turbulent suspension flow has been set up. Based on it, a method of transformation of empirical spatial-time mean values into probabilistic ones with allowance made for the influence of hydrodynamic quantity field nonuniformity as well as of the averaging volume form and size on the relative difference of the studied mean values from each other has been developed. A condition wherein the empirical spatial-time mean values practically coincide by its magnitude with probabilistic ones, and the spatial-time mean values being measured can be used for comparing results of the turbulence statistical model in this case has been found.
Lagrangian Model of Oil Slick Spreading
3
10.1615/InterJFluidMechRes.v30.i1.80
Vladimir S.
Maderich
Institute of Problems of Mathematical Machines and Systems of National Academy of Sciences of Ukraine, Kyiv, Ukraine
L. I.
Koziy
Institute of Problems of Mathematical Machines and Systems of National Academy of Sciences of Ukraine, Kyiv, Ukraine
In contrast to the earlier models, within which the dynamics of the separate stages of the slick spreading was considered independently, we put forward a unified semi-empirical equation, which describes the balance of all the principal forces governing the oil slick spreading.
Numerical Simulation of Turbulent Flows over Compliant Surfaces
18
10.1615/InterJFluidMechRes.v30.i1.90
Gennadii A.
Voropayev
Institute of Hydromechanics of National Academy of Sciences of Ukraine, 8/4, Zhelyabov St.,
Kyiv, Ukraine
N. V.
Rozumnyuk
Institute of Hydromechanics of National Academy of Sciences of Ukraine, Kyiv, Ukraine
A closed system of equations, governing the hydrodynamic interaction between a turbulent boundary layer and a deformable viscoelastic surface which simulate the skin integument of cetaceans, is obtained in the paper. The generalizations of the closure hypothesis for the mechanisms of redistribution and turbulent diffusion (third moments) in the transport equations for the second moments are developed. The approximations of boundary conditions suggested in the paper account for the energy exchange through the deformed interface between the turbulent boundary layer and the viscoelastic layer. The variation range of the mechanical and geometrical parameters of the viscoelastic covers as functions of a velocity of the flow is determined. The numerical results which provide an explanation for the friction drag reduction in the aquatic life are obtained.
Seismic Action of the Cylindrical Charge Explosion
14
10.1615/InterJFluidMechRes.v30.i1.100
A. A.
Vovk
Institute of Hydromechanics of National Academy of Sciences of Ukraine, Kyiv, Ukraine
A. A.
Kuzmenko
Institute of Hydromechanics of National Academy of Sciences of Ukraine, Kyiv, Ukraine
The inconsistency of use of the spherical charge formula for definition of a ground displacement velocity caused by a cylindrical charge explosion is shown. The results of experimental researches of intensity of ground fluctuations at a vertical cylindrical charge explosion are given and the formulas for definition of a ground displacement velocity for the body and the surface waves in various grounds at the lengthened charge explosion are received. The influence of constructed features of a cylindrical charge on parameters of seismic-exploding waves is investigated.