Begell House Inc.
International Journal of Fluid Mechanics Research
FMR
2152-5102
30
2
2003
Announcement of NATO Advanced Study Institute in Kyiv, Ukraine, May 4–15, 2004
2
Hydrobionic Principles of Drag Reduction
22
V. V.
Babenko
Institute of Hydromechanics of National Academy of Sciences of Ukraine, Kyiv, Ukraine
Features of organism's systems and their interaction in a course of motion of aquatic animals, which reduces the power consumption, are the subject of investigation. The principles of operation of the hydrobionts, the morphological and physiological features of the skeleton, muscles, skin integuments, circulatory system and innervation of dolphins are considered with allowance made for the influence of the environment on the organism. It is studied how the velocity of swimming, the non-stationarity of the flow, the non-traditional mode of creation of the traction and the specific structure of a body influence the organism's systems. A temperature on the surface of a body, distribution of the elasticity, damping properties of the skin and characteristics of the turbulent boundary layer are measured at various modes of motion of a dolphin. The operation of the organism's systems and the mechanisms of control of the mechanical properties of a skin, which depend on the velocity of swimming, are considered. The hydrodynamic simulation of the organism's systems is performed. The experimental results for some models of the organism's systems of the hydrobionts are presented.
Wavelets in the Transport Theory of Heterogeneous Reacting Solutes
6
Carlo
Cattani
Dipartimento di Matematica "G. Castelnuovo", Univ. di Roma "La Sapienza'' P. Ie A. Moro 5,1-00185 Roma ; and DiFarma, University of Salerno Via Ponte Don Melillo, 84084 Fisciano (SA), Italy
E.
Laserra
Dipartimento di Matematica e Informatica, Univ. di Salerno, Via S.Allende, 1-84121 Baronissi (SA), Italy
In this paper we consider the one-dimensional convection (advection) dispersion equation of the transport theory of heterogeneous reacting solutes in porous media. A wavelet solution is in the framework of multi-resolution analysis.
Generation of Surface Waves and Vortices by a Displacement of the Elliptic Part of the Basin's Bottom
13
S. F.
Dotsenko
Marine Hydrophysical Institute of NAS of Ukraine, Sevastopol, Ukraine
The generation of spatial waves and vortices in a rotating fluid layer of constant depth is analyzed within the limits of the linear model of long waves. Small vertical finite-duration displacements of a part of the basin's bottom serve as the excitation source. The integral expressions for both the hydrodynamic fields and the total energy of the fluid motion are found. A number of general properties of the dynamic process are established. The influence of the rotation of medium on the dynamics of fluid is quantitatively estimated on the basis of the evaluation of the double integrals in the case of the linear finite-duration deformations of the elliptic segment of the basin's bottom. This problem is of obvious interest in the context of the effects accompanying the seismic generation of tsunami.
Two Approaches to the Analysis of the Coaxial Interaction of Vortex Rings
18
V. V.
Meleshko
Institute of Hydromechanics of National Academy of Sciences of Ukraine, Kyiv, Ukraine
G. J. F.
van Heijst
Department of Applied Physics, Eindhoven University of Technology, Eindhoven, The Netherlands
Two models for describing vortex rings: the Dyson's model with a continuous vorticity distribution and the vorton model with discrete vorticity distribution, which both can be used to describe the coaxial interaction of two identical vortex rings, are compared. The presentation of motion equations of both models in a similar formulation makes possible an extended analysis of both the analogies and differences between the models: comparing trajectories, impulses and energies of the vortex rings system in both cases for periodical interaction of two identical vortex rings in an unbounded fluid. The slightly different trajectories can be entirely explained theoretically from the respective equations of motion for vortex rings and vorton rings. The analysis of matching and comparison of the initial parameters of two different models, which both describe the same interaction, is presented in this article. A possible criterion, which can be used for description of a non-coaxial interaction of vortex rings by means of discrete vorton model, was obtained.
Experimental Investigations of the Vortex Ring Transformation in a Laminar Stratified Shear Flow
3
O. D.
Nikishova
Institute of Hydromechanics of National Academy of Sciences of Ukraine, Kyiv, Ukraine
V. I.
Nikishov
Institute of Hydromechanics of National Academy of Sciences of Ukraine, 8/4, Zhelyabov St.,
Kyiv, 03057, Ukraine
V. V.
Oleksiuk
Institute of Hydromechanics of National Academy of Sciences of Ukraine, Kyiv, Ukraine
The results of the experimental investigations of the transformation of vortex structures (vortex rings) in a laminar shear stratified flow are presented. The stratification is shown to reduce a height of lift of the vortex ring ejected in the vertical direction across the flow. It is found that the behavior of the vortex rings in a shear flow differs drastically from the behavior of the same rings in a stationary fluid. It is demonstrated that two solitary waves traveling along the core of a ring in the opposite directions appear induced by the effect of shear. This leads to the scattering of the rings' trajectories.
Features of the "Tissue" Sound Propagation Channel in Human Thorax
14
Valery
Oliynik
Institute of Hydromechanics of National Academy of Sciences of Ukraine
The acoustic propagation through biological tissues of a thorax with allowance for availability of its costal framework and the surface soft tissues is investigated. Estimations of the density, the sound speed and the attenuation coefficient in the lung parenchyma and the soft biotissues are obtained. Within the approach of linear acoustics the mathematical model is developed permitting to assess quantitatively a performance of the sound transmission from the lung to the surface of the human body. It is shown that at propagation of the sound in the considered system the piston mode dominates. It is shown that when the breath sounds propagate in the thorax, the effect of its costal grating is exhibited by the constant additional loss of the signal. It is shown that the low-frequency domains of the spectrum of normal respiratory sounds are formed by the sources disposed on whole volume of the lung. The high-frequency spectrum is formed predominantly by the sources disposed on the lung's peripherals.
3-D Stability of Boundary Layer Flows over Laminate Plates Like Compliant Coatings
18
Adrian
Postelnicu
Department of Thermal Engineering and Fluid Mechanics, Transilvania University of Brasov, Brasov, Romania
Ioan
Pop
Department of Applied Mathematics, Babes-Bolyai University, 400084 Cluj-Napoca, Romania
The paper deals with a 3-D model for the linear stability of an incompressible boundary layer flow over laminate plates like compliant coatings. The main flow considered is of Blasius type, while the disturbance modes are described by an Orr-Sommerfeld type equation and a Squire equation. These equations arc solved numerically using a shooting technique. The compliant coating proposed is a new one: a laminate compliant plate which is connected to the rigid base by a liquid viscous sublayer. After implementation of the matching conditions between the flow and solid coating, the governing equations are solved numerically for a particular geometrical model. Results are presented for the Tollmien-Schlichting instability regime.
Wave Processes in Fluids and Elastic Media
30
Igor T.
Selezov
Institute of Hydromechanics of National Academy of Sciences of Ukraine, Zhelyabov St., 8/4, Kyiv, 03680, MSP, Ukraine
Some wave models are developed and investigated for water wave propagation, magnetohydrodynamic and hydroelastic waves and their interaction with local inhomogeneities. Extended evolution equations (nonlinear-dispersive approximations) for water wave propagation are derived from which known approximate theories of nonlinear water wave propagation follow as particular cases. The initial boundary value problem for the soliton evolution over an uneven bottom is investigated. The degenerated models of magnetohydrodynamics and magnetoelasticity of slight and perfect electroconductivity are constructed and the possibility of introduction of the potentials are shown. The problem of MHD-wave scattering by a cylinder is considered. The equations of magnetoelasticity are extended to the case of the medium with voids and the equations of magnetizable magnetoelastic medium are extended to the case of active interactions. A new initial boundary value problem for the pressure pulse propagation in a blood vessel consisting of jointed vessels of different radii and thicknesses is stated and solved by using Laplace transform in time. The effect of a vessel joint on the heart pressure pulse propagation is investigated in detail. The strong concentration of thickness-shear and bending stresses at the vessel joint has been discovered.