Begell House Inc.
International Journal of Fluid Mechanics Research
FMR
2152-5102
33
6
2006
Boundary Layer Flow and Drag Estimation on the Body of Moving Car
489-499
Vakkar
Ali
Department of Mechanical Engineering, Faculty of Engineering & Technology, Jamia Millia Islamia, New Delhi - 110025, India
M.
Islam
Department of Mechanical Engineering, Faculty of Engineering & Technology, Jamia Millia Islamia, New Delhi - 110025, India
Abdur
Rahim
Department of Mechanical Engineering, Faculty of Engineering & Technology, Jamia Millia Islamia, New Delhi - 110025, India
S. Naseem
Ahmad
Department of Mathematics, Jamia Millia Islamia, New Delhi - 110025
A boundary layer flow has been considered for studying the drag force on the surface of a moving car. We have divided body of car into three main portions, where side span portion is not been considered. The portion, facing the driver was considered as a moving plate and the portion including the wind screen was taken as a wedge. The influence of car velocity and wind screen angle on the drag force is obtained by numerical computation.
Unsteady Free Convective Viscoelastic Boundary Layer Flow Past a Vertical Porous Plate with Internal Heat Generation/Absorption
500-522
Ioan
Pop
Department of Applied Mathematics, Babes-Bolyai University, 400084 Cluj-Napoca, Romania
Sujit Kumar
Khan
Department of Mathematics, Gulbarga University, Gulbarga, 585 106, Karnataka, India
Unsteady boundary layer free convection flow of an incompressible electrically conducting viscoelastic second-order fluid over a vertically permeable flat plate is considered, where temperature and concentration differences are responsible for the convective buoyancy current. The flow is affected by a constant suction of fluid through the permeable wall in the presence of a temperature-dependent heat source/sink and applied transfer magnetic field. This intricate mathematical problem has been solved analytically. The analysis has been carried out for small values of the viscoelastic parameter and the results are presented in table and graphical form. The effect of various nondimensional physical parameters, such as the viscoelastic parameter, Grashof number Gr, modified Grashof number Gm, source/sink parameter, frequency parameter, time dependency parameter, Prandtl number, Schmidt number, permeability parameter, and magnetic parameter, on the boundary layer velocity and skin-friction coefficient are investigated. Some of the several important findings of the results are: (i) the increase of the velocity in the boundary layer with the increase of viscoelastic parameter is significant for higher values of the Grashof number; (ii) the combined effect of increasing the values of viscoelastic parameter, modified Grashof number, and permeability parameter is to enhance the horizontal velocity profile largely in the boundary layer; (iii) the effect of increasing the value of the Prandtl number is to decrease the skin-friction coefficient for smaller values of viscoelastic parameter, and its effect is to increase the skin-friction parameter for higher values of viscoelastic parameter in the presence of convective current generated by cooling of the boundary wall and concentration gradient (both Gr and Gm positive); (iv) the limiting value of viscoelastic parameter for which separation of boundary layer takes place is higher for higher values of permeability parameter and Hartmann number, and lower values of Prandtl number; (v) the effect of temperature-dependent heat source is to enhance the reverse flow in the negative x direction near the boundary wall more significantly in the case of a viscoelastic fluid than a viscous fluid.
Modelling the Effect of Compositional Changes in Transient Flow of Gas Condensate Reservoirs
523-536
Olanrewaju
Oyewola
Discipline of Mechanical Engineering, The University of Newcastle NSW, 2308, Australia
A. F.
Olaberinjo
Chemical Engineering Department, University of Lagos, Nigeria
This paper considers the flow behavior in gas condensate reservoir and presents an approach for calculating the pressure depletion performance of a gas condensate reservoir from the original reservoir fluid composition using the vapor-liquid equilibrium calculations, the fluid properties and retrograde liquid accumulation as guides. The results correspond to drawdown analysis of a condensate reservoir where flow of the phases occurs and comparison with other standard work on transient pressure analysis of gas condensate reservoirs was satisfactory. A principal use of the method would be for the initial estimation of pressure depletion pattern after discovery of a gas condensate reservoir, where the compositional analysis of the reservoir fluid may be only approximate and the dew point if not known, is assumed to be the reservoir temperature and pressure. It is also a valuable tool during the production period for reservoir surveillance and monitoring.
Investigation of Pressure - Flow Relations and the Parameters of the Forward and Backward Pressure Waves in Arterial Beds
537-552
N. N.
Kizilova
V. N. Karazin Kharkiv National University, Ukraine
Wave motion of a viscous incompressible liquid in a model of the intraorgan arterial bed consisting of a thin long viscoelastic tube connected in series with a terminal element, characterized by complex wave conductivity, is investigated. Within the framework of an axysymmetrical model of wave motion of the liquid in the thick-walled cylindrical tube the expressions are obtained for the pressure and volume flow waves. For equations averaged over the tube cross-section the expressions for the Riemann invariants and intensities of the incident and reflected compression and expansion waves are obtained. Biomechanical interpretation for pressure-flow dependence and the parameters of the incident and reflected waves are developed by comparing the numerical results. Important diagnostic parameters, allowing to estimate the blood circulation conditions in the viscus upon the measurements of pressure and flow in feeding artery are determined. Wave diagram of pressure and flow variation in aorta and pulmonary arteries is analyzed. The obtained results can be used for developing the innovative non-invasive diagnostic techniques of viscera state estimation.
Stability of Wave Packets in Layered Hydrodynamic Systems Subjected to the Surface Tension
553-566
Olga V.
Avramenko
Kirovograd State V. Vinnichenko Pedagogical University, Kirovograd
Igor T.
Selezov
Institute of Hydromechanics of National Academy of Sciences of Ukraine, Zhelyabov St., 8/4, Kyiv, 03680, MSP, Ukraine
The non-linear problems on propagation of wave packets at the interface between two fluids of different density with allowance for the surface tension are studied. Two problems are considered, the first one for two half-spaces, the second one for the layer overlying a half-space. The stability condition for the complex envelope of wave packets is derived on the basis of non-linear Schroedinger equation obtained by multiscale expansions up to the fourth approximation. The numerical and asymptotic analysis reveals a new domain of instability of gravity waves and a new domain of stability of capillary waves.
Structure of Nonlinear Wave Packets on the Interface of Liquid Media
567-583
Olga V.
Avramenko
Kirovograd State V. Vinnichenko Pedagogical University, Kirovograd
Igor T.
Selezov
Institute of Hydromechanics of National Academy of Sciences of Ukraine, Zhelyabov St., 8/4, Kyiv, 03680, MSP, Ukraine
The paper deals with investigating the amplitudes of higher harmonics in nonlinear wave packets on an interface of liquid media; surface tension is taken into account. Based on a solution obtained by a multiple-scale expansion method, the structure of the packets in the symmetric system "half-space − half-space" and in the asymmetric system "layer − half-space" is studied. It has been established that, unlike the first approximation, each subsequent one determines the amplitude of the respective higher harmonic only approximately, and at the same time it makes corrections to the amplitude of each preceding harmonic. The third-approximation solution reveals the existence of an extreme value of the higher-harmonic amplitudes at certain values of the first harmonic's length and the layer's thickness. The dependence of the wave packet's shape vs the surface tension and the ratio between the height and the length of the first harmonic has been found out.