Begell House Inc.
International Journal of Fluid Mechanics Research
FMR
2152-5102
35
2
2008
On the Source Potential in the Presence of a Vertical Cliff in an Ocean
95-103
Prabir Kumar
Kundu
Department of Mathematics, Jadavpur University, Kolkata 700032, W.B., India
Partha
Agasti
Department of Mathematics, Debipur Milan Vidyapih, Debipur, Purba Medinipur, West Bengal, Kolkata-721650, INDIA
An alternative method essentially based on a simple reduction procedure and inverse Fourier sine transform technique is employed here to reinvestigate the three-dimensional problem of in-coming surface water waves against a rigid vertical cliff in an ocean of infinite depth. Assuming linear theory, analytical expressions for the velocity potentials are obtained here by ignoring the effect of surface tension and also by considering the effect of surface tension at the free surface. Various known results are recovered as special cases.
Numerical Modelling of Transient Mass Transfer in an Aquifer With Simultaneous First Order Chemical Reaction and Second Order Decay
104-129
A. S.
Warke
Symbiosis Institute of Technology, Lavale Campus, Dynamics, Pune - 411 042, India
Samir K.
Das
Department of Computational Fluid Dynamics, International Institute of Information Technology, P-14, Rajiv Gandhi Infotech Park, Hinjawadi, Pune- 411057, India
O. Anwar
Bég
Fluid Mechanics, Nanosystems and Propulsion, Aeronautical and Mechanical Engineering,
School of Computing, Science and Engineering, Newton Building, University of Salford,
Manchester M54WT, United Kingdom
Harmindar S.
Takhar
Engineering Department, Manchester Metropolitan University, Oxford Rd., Manchester, M15GD, UK
Tasveer A.
Beg
Engineering Mechanics Associates, Manchester, M16, England, United Kingdom
A mathematical model to simulate contaminant dispersion in a homogeneous, isotropic aquifer under the influence of second order decay as well as first order chemical reaction at the boundary is presented. A finite difference implicit (ADI) scheme has been employed to solve the two-dimensional transport equation. Numerical experiments were carried out for two types of disposal scheme, i) Scenario-I: longer duration with low concentration and ii) Scenario-II: short duration with high concentration. In both the scenarios, contaminant inflow rate is considered to be proportionately analogous to the inflow concentration and therefore two types of input correspond to the same amount of waste load. The influence of reaction parameter (β) and decay parameter (μ) on the contaminant dispersion have been studied for two years, four years and six years of simulations. The reaction at the upper boundary behaves as a catalytic reaction, causing depletion of contaminant plume and its growth. With the increase of reaction parameter (β), spreading of contaminant is controlled very significantly. The decay parameter (μ) takes a significant role to reduce the plume size when long time is allowed. Model simulations indicate that when the boundary reaction is mild and decay is insignificant, scenario-I can be chosen for a short period after release. If strong treatment is subjected for a long time, scenario-II is a better option as it controls the contaminant spread significantly.
Visualization and Scaling of Coherent Eddies in Wall-Bounded Turbulent Flows at Relatively Low Reynolds Numbers
130-145
Susanta K.
Das
Department of Chemical Engineering, McGill University, 3610 University Street, Montreal, Quebec H3A 2B2, Canada; and Department of Mechanical and Aerospace Engineering, Tokyo Institute of Technology 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552, Japan
Mamoru
Tanahashi
Department of Mechanical and Aerospace Engineering Tokyo Institute of Technology 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
S.
Shiokawa
Department of Mechanical and Aerospace Engineering, Tokyo Institute of Technology 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552, Japan
Toshio
Miyauchi
Dept. Mechanical and Aerospace Eng., Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552, Japan; Organization for the Strategic Coordination of Research and Intellectual Properties Meiji University 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa, Japan
Visualization of coherent eddies in fully developed turbulent channel flows based on the scaling with characteristic variables associated with wall-bounded turbulence is performed using the results of the direct numerical simulation (DNS). DNS databases obtained by solving three-dimensional Navier-Stokes equations with different Reynolds number, based on the wall friction velocity and channel half, are employed to perform the visualization. The main objective is to assess the suitability of the characteristic variables of turbulence for direct visualization of coherent eddies in the instantaneous flow fields. Normalization variables used for turbulent statistics are examined to judge the best scaling variables of coherent eddy. The results show that the coherent eddies in fully developed turbulent channel flows is best visualized when scaled with Kolmogorov scale. The streamwise and the hairpins (loop-like) can be visualized simultaneously. The simulation results may provide an important insight to uncover behaviors of coherent eddies in turbulent flow fields.
Experimental Investigations into Defrost Mode Flow for Vehicle Thermal Comfort
146-162
M.
Alhajri
Mechanical P. Eng Dept, Faculty of Tech. Study, Kuwait
A.
Arrousi
Management, Manufacturing, Material and Mechanical Eng. School, Nottingham University, England
S.
Agil
Management, Manufacturing, Material and Mechanical Eng. School, Nottingham University, England
The air conditioning system of vehicle requires approximately four thousands watts of mechanical power to operate and satisfy the human comfort while human body dissipates only one hundreds watts to the environments. The consumption of the fuel in United States for use of HVAC systems in vehicles is approximately twenty six litres [18].
This paper describes the measurements for the one-fifth scaled model used of passenger car. The measurements are obtained using the Particle Image Velocimetry (PIV) and Laser Doppler anemometry (LDA) techniques. The analysis of the flow inside the model is obtained and discussed for defrost ventilation mode. The effects of this mode on the occupants are examined under the presence of a driver manikin in position and no other passengers are included in the model. The measurements of the velocity flow field are taken at various planes in the vertical and horizontal directions.
Theoretical Approach on the Study of Turbulent Water Flow over Smooth and L-shaped Riblets Surfaces
163-172
Abdelhafid
Brima
Department of Mechanics University of Biskra, Algeria; Research laboratory in Mechanical Engineering (LGM), Biskra University, Po Box. 145, 7000, ALGERIA
Rachid
Atmani
Department of Mechanics University of Biskra, Algeria; Research laboratory in Mechanical Engineering (LGM) Biskra University, Po Box. 145, 7000, ALGERIA
Bachir
Achour
Research Laboratory in Subterranean & Surface Hydraulics, Department of Hydraulics, University of Biskra, Biskra, Algeria
A very important research effort has been developed at many world laboratories these last years in order to reduce the friction drag. For the aircraft and the submarine applications, friction contributes respectively for about 50% and 70% of the total resistance. The use of surface modifications riblets as a means of reducing viscous drag on a body has potential aerodynamic and hydrodynamic applications. In the present study, the theoretical approach allow to determine the velocity field, the wall shear stress, the local skin friction, the boundary layer thickness, the laminar sub layer thickness and the dimensionless drag coefficient. The results found, indicate that the presence of L-shaped riblets surfaces provide changes in the characteristics of the turbulent boundary layer, which are in favor of wall skin friction.
The Effect of Heat Transfer on Unsteady Hydromagnetic Flow in a Parallel-Plate Channel of an Electrically Conducting, Viscous, Incompressible Fluid
173-187
Krishna Gopal
Singha
Department of Mathematics, Dibrugarh University, Dibrugarh, Assam, India
An analytical study has been performed to examine the effect of heat transfer characteristics on the flow of a viscous, incompressible electrically conduction fluid in a parallel plate channel under the action of transverse magnetic field when (i) the two plates are kept at different but constant temperatures, (ii) the upper plate is given to move with constant velocity while the lower plate is adiabatic. The governing partial differential equations of this problem, subject to boundary conditions are solved analytically for fluid velocities, magnetic field and temperature distributions. The graphical representation for the velocity, the induced magnetic field, temperature distributions and the heat transfer are depicted graphically for different values of dimensionless parameters of the problem and the analysis of the results showed that the flow field is appreciably influenced by the applied magnetic field.
Effect of Stricture Length on Reattachment Point and Wall Shear Stress Through a Stenosed Coronary Artery
188-202
Dipak Kumar
Mandal
Deptartment of Mechanical Engineering, College of Engineering & Management, Kolaghat,
P.O: K.T.P.P. Township, Midnapore (E) - 721171, West Bengal, India
Somnath
Chakrabarti
Department of Mechanical Engineering, Indian Institute of Engineering Science and Technology Shibpur, Howrah, 711103, West Bengal, India
A numerical study has been carried out to investigate disturbances of blood flow through a stenotic coronary artery for the restrictions of 10% to 90% with the Reynolds numbers ranging from 25 to 375 for the stricture length varying from 0.1 to 2.0. Reattachment point, wall shear stress, and it's physiological aspects have been studied in detail. From this study, it is revealed that the effect of stricture length on wall shear stress and reattachment point is maximum at low stricture length. This effect gradually decreases with the increase in stricture length. This may help to stop further aggravation of plaque deposition.