Browsing by Author "A. Raptis"

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Effects of MHD free convection and mass transfer on the flow past a vibrating infinite vertical circular cylinder
(Springer-Verlag, 1989) A.K. Agrawal; B. Kishor; A. Raptis
The effects of MHD free convection and mass transfer are taken into account on the flow past a vibrating infinite isothermal and constant heat flux vertical circular cylinder. The expressions for velocity, temperature, concentration and skin-friction of the fluid are obtained in closed form by using Laplace transform technique. The effects of Pr (Prandtl number), Sc (Schmidt number), Gr (Grashof number, Gr>0 implies cooling and Gr<0 heating of the cylinder), Gm (modified Grashof number), M (magnetic field parameter) and variation of time on velocity distribution have been studied graphically. The results presented in this paper agree with the results of Lien and Chen when magnetic parameter approaches zero. © 1989 Springer-Verlag.
Finite difference analysis of unsteady free convective flow through a porous medium adjacent to a semi-infinite vertical plate
(1987) A. Raptis; A.K. Singh; K.D. Rai
Explicit finite-difference analysis of free convective flow through a porous medium bounded by a semi-infinite vertical plate is carried out. The transient and steady state velocity and temperature profiles are shown on graphs and table. It has been observed that the velocity components increases with permeability parameter where as temperature decreases with it. © 1987.
Free-convection flow of water at 4°C past an infinite vertical porous plate with constant heat flux
(Kluwer Academic Publishers, 1984) A.K. Singh; A. Raptis
An analysis of the two-dimensional flow of water at 4°C past an infinite porous plate is presented, when the plate is subjected to a normal suction velocity and the heat flux at the plate is constant. Approximate solutions are derived for the velocity and temperature fields and the skin-friction. The effects of G (Grashof number) and E (Eckert number) on the velocity and temperature fields are discussed. © 1984 D. Reidel Publishing Company.
Hydromagnetic Rayleigh problem in a rotating fluid
(1986) A. Raptis; A.K. Singh
An analysis of the MHD Rayleigh problem of a rotating fluid above a plate is carried out, when the magnetic Reynolds number of the flow is small and the magnetic field is fixed on the plate. An exact solution is obtained with the help of the Laplace transform technique. It is found that the effect of the magnetic field increases the primary flow and decreases the secondary flow. © 1986 with the authors.
MHD free convection flow past an accelerated vertical plate
(1983) A. Raptis; A.K. Singh
The effect of a uniform transverse magnetic field on the free convection flow of an electrically conducting fluid past an infinite vertical plate for both the classes of impulsive as well as uniformly accelerated motion of the plate is discussed. In this analysis, the magnetic lines of force are assumed to be fixed relative to the plate. Laplace transform technique has been used to obtain the expressions for the velocity field and skin-friction for both cases. It is found that the effect of the magnetic field is to increase the velocity field in both cases. © 1983.
UNSTEADY HYDROMAGNETIC FREE-CONVECTIVE FLOWS WITH HALL CURRENT.
(1987) A.K. Singh; A. Raptis
The unsteady free-convective flow of an electrically conducting fluid near a moving vertical plate of infinite extent is investigated in the presence of a strong transverse magnetic field by taking into account the Hall current. The flow is assumed to be at a small magnetic Reynolds number so that the induced magnetic field is neglected. Exact solution of this problem is obtained by defining a complex velocity with the aid of the Laplace transform technique, when the plate is moving with a velocity which is an arbitrary function of time. The solution is exemplified for three particular cases of physical interest and it is found that the free-convection currents have same effects for all cases of plate motion.