共查询到20条相似文献，搜索用时 796 毫秒
1.
A. K. Singh 《Astrophysics and Space Science》1983,93(1):1-13
Hall effects on the hydromagnetic free convection flow of an electrically conducting incompressible viscous fluid past a steadily moving vertical porous plate has been analysed when the free stream oscillates in magnitude. The flow is subjected to a constant suction, through the porous plate, and the difference between wall temperature and the free-stream is moderately large causing the free convection currents. The mathematical analysis is presented for the hydromagnetic boundary layer flow without taking into account the induced magnetic field. This is a valid assumption for small magnetic Reynolds number. Approximate solutions for the components of velocity field and temperature field and their related quantities are obtained. The influence of various parameters entering into the problem is extensively discussed with the help of graphs and tables. 相似文献
2.
A. Gholizadeh 《Astrophysics and Space Science》1990,174(2):303-310
Effects of temperature-dependent heat source on hydromagnetic free-convection flow (set up due to temperature as well as species concentration) of an electrically-conducting incompressible viscous fluid past a steadily moving vertical porous plate through high porous medium has been analysed when the free stream oscillates in magnitude. The flow is subjected to a constant suction, through the porous plate. The mathematical analysis is presented for the hydromagnetic flow without taking into account the induced magnetic field. This is a valid assumption for small magnemtic Reynold number. Approximate analysis for the velocity and temperature field and their related quantities are obtained. The influence of various parameters entering into the problem is extensively discussed with the help of graphs and tables. 相似文献
3.
A. K. Singh 《Astrophysics and Space Science》1984,107(1):125-134
Rotation effect on the hydromagnetic free-convection flow of an electrically conducting, viscous, and incompressible fluid past a steadily moving vertical porous plate has been analysed in the presence of a transverse magnetic field. The free-stream velocity oscillates in time about a constant mean, while the suction velocity, normal to the porous plate, is constant. The magnetic Reynolds number of the flow is taken small enough so that the induced magnetic field can be neglected. The plate temperature is constant and the difference between the temperature of the plate and the free stream is moderately large causing the free-convection currents. The flow field is described by nonlinar coupled system of equations. With viscous dissipative heat taken into account, approximate solutions of the problem are obtained for the components of velocity field and temperature field as well as for the skin-friction components and rate of heat transfer. 相似文献
4.
N. G. Kafousias A. A. Raptis G. J. Tzivanidis C. V. Massalas 《Astrophysics and Space Science》1981,78(1):157-168
Unsteady hydromagnetic boundary layer flow of a viscous incompressible and electrically conducting fluid past an infinite
vertical non-conducting porous limiting surface in presence of a transverse magnetic field, is considered when the limiting
surface is moving impulsively in its own plane and is subjected to a constant suction. The free stream oscillates in time
about a constant mean value and the magnetic Reynolds number is taken to be small enough so that the induced magnetic field
is negligible. As the mean steady flow has been presented in Part I, only the solutions for the transient velocity profiles,
transient temperature profiles, the amplitude and the phase of the skin friction and the rate of the heat transfer are presented
in this work. The influence of the various parameters entering into the problem, especially of the magnetic parameterM, is extensively discussed. A comparative study with hydrodynamic case (M=0) is also made. 相似文献
5.
N. G. Kafousias A. A. Raptis G. A. Georgantopoulos C. V. Massalas 《Astrophysics and Space Science》1980,71(2):337-352
In this work we present the two-dimensional free convection flow of an incompressible viscous fluid past an infinite vertical limiting surface (porous wall) for the Stokes's problem when the fluid is subjected to a constant suction velocity. The flow is normal to the porous wall and the free stream oscillates about a mean value. As the mean steady flow has been presented in Part I, only the solutions for the transient velocity profiles, transient temperature profiles, the amplitude and the phase of the skin friction and the rate of heat transfer are presented in this work. As in the case of mean steady flow, the influence of the Grashof numberG and Eckert numberE on the unsteady flow field is discussed for air (P=0.71) and water (P=7) and for the cases of externally heating and cooling the porous limiting surface by free convection currents. 相似文献
6.
I. A. Hassanien 《Astrophysics and Space Science》1989,151(1):73-80
Unsteady two-dimensional hydromagnetic free convection and mass transfer flow of an electrically-conducting viscous-incompressible fluid, through a highly porous medium bounded by a vertical plane surface of constant temperature is considered. The free-stream velocity of the fluid vibrates about a mean constant value and the surface absorbs the fluid with constant velocity. Expressions for the velocity, temperature, concentration are obtained. Effects of Gr (Grashof number), Gm (modified Grashof number),K (permeability of the porous medium), (frequency parameter), andM (magnetic parameter) upon the velocity field are discussed. 相似文献
7.
With viscous dissipation and Joule heating taking into account the hydromagnetic two-dimensional oscillating free-convection flow, of a viscous, incompressible and electrically conducting fluid, past an infinite vertical porous limiting surface, is studied. For the solution of the problem it is considered that, the free-stream velocity, the plate temperature and the induced magnetic field are oscillating in the time about constant mean values. The flow is subjected to a constant suction velocity, through the porous surface, and a magnetic field of uniform strength is applied transversely to the direction of the flow. Analytical expressions for the flow field are obtained by solving the coupled non-linear system of equations which describe the flow. The influence of the various parameters entering into the problem is also extensively discussed signifying the importance of retaining the Joule heating and viscous dissipation term in the energy equation. 相似文献
8.
N. G. Kafousias C. N. Douskos G. L. Vassios G. A. Georgantopoulos C. L. Goudas 《Astrophysics and Space Science》1981,74(2):265-272
An analysis of the temperature field in the case of the two-dimensional hydromagnetic flow of a viscous incompressible and electrically conducting fluid, (e.g., of a stellar atmosphere), past a porous, infinite, limiting surface in the presence of a transverse magnetic field, is considered when (i) the free stream velocity oscillates in time about a constant mean; (ii) the suction velocity normal to the limiting surface oscillates in magnitude but not in direction about a non-zero mean; and (iii) there is no heat transfer between the fluid and the wall. Approximate solution is obtained of the energy equation and are given expressions for the temperature field and for the temperature at the limiting surface, when the magnetic Prandtl numberP
m
=1 and the magnetic parameterM<1. They are shown graphically followed by a discussion.Research supported by the Alexander S. Onassis Foundation. 相似文献
9.
A study is made of the free convection in hydromagnetic flows through a porous medium of a heat generating fluid past an infinite vertical porous plate. A strong magnetic field is imposed in a direction which is perpendicular to the free stream and makes an alge to the vertical direction. The governing equations for the hydromagnetic fluid flow and the heat transfer are solved analytically. The influence of Hall currents, the permeabilityK and the inclination upon the velocity field are shown in figures. 相似文献
10.
A. Gholizadeh 《Astrophysics and Space Science》1991,180(2):287-292
In this work we present the effects of temperature-dependent heat source on hydromagnetic free-convection flow (set up due to temperature as well as species concentration) of an electrically-conducting incompressible viscous fluid past a steady moving vertical porous plate through high porous medium when the free stream oscillates in magnitude. The flow is subjected to a constant suction through the porous plate. As the mean steady flow has been presented gy Gholizadeh (1990), only the solution for the transient velocity profiles, transient temperature profiles, the skin-friction (steady+unsteady), and rate of heat transfer are presented in this work. 相似文献
11.
P. Hatzikonstantinou 《Astrophysics and Space Science》1985,115(1):185-194
The problem of unsteady hydromagnetic axial flow near the porous surface of a sphere or a cylinder is studied numerically. The fluid is considered to be electrically conducting, viscous and incompressible subjected to a magnetic field. Results are presented for the case of injected or sucked fluid with a constant velocity through the porous surfaces. The magnetic Prandtl number is set equal to one, while the magnetic Reynolds number is taken to be small enough so that the inducted magnetic field is negligible. 相似文献
12.
N. G. Kafousias A. A. Raptis G. A. Georgantopoulos C. L. Goudas 《Astrophysics and Space Science》1981,76(1):133-148
Unsteady two-dimensional free convection flow of an electrically conducting, viscous, incompressible fluid, past an infinite vertical porous limiting surface in the presence of a transverse magnetic field is studied, when the limiting surface is moved impulsively with a constant velocity, either in the direction of the flow or in the opposite direction. The magnetic Reynolds number of the flow is not taken to be small enough so that the induced magnetic field is not negligible. The obtained results, for the mean steady flow phenomena, are discussed with the aid of graphs and tables for different values of the dimensionless parameters entering into the problem. 相似文献
13.
A. K. Singh 《Astrophysics and Space Science》1983,97(2):453-460
In this work we present the effects of Hall current on the hydromagnetic free-convection flow of a viscous, incompressible and electrically conducting fluid past an infinite vertical porous plate for the Stokes problem when the fluid is subject to a constant suction velocity. The flow is normal to the porous plate and the free-stream oscillates about a mean value. As the mean steady flow has been presented in part I, only the solution for the transient primary velocity profiles, transient secondary velocity profiles, transient temperature profiles; the amplitude and phase of skin-friction components and the rate of heat transfer are presented in this work. As in the case of mean steady flow, the influence of the various parameters on the unsteady flow field is discussed with the help of graphs and tables for both the cases cooling and heating of the porous plate. 相似文献
14.
An analysis of a two-dimensional steady-free convection and mass transfer flow of an incompressible, viscous, and electrically conductive non-Newtonian fluid through a porous medium bounded by a vertical infinite limiting surface (plane wall) has been presented in the presence of a transverse magnetic field. Approximate solutions to the coupled nonlinear equations governing the flow are derived and expression for the velocity, temperature, concentration, the rate of heat transfer, and the skin-friction are derived. Effects of Gr (Grashof number), Gm (modified Grashof number),M
* (non-Newtonian parameter),N (magnetic parameter), and permeabilityK of the porous medium on the velocity, the skin-friction and the rate of heat transfer are discussed when the surface is subjected to a constant suction velocity. 相似文献
15.
Hall effects on the hydromagnetic free convection resulting from the combined effects of thermal and mass diffusion of an electrically conducting liquid past an infinite vertical porous plate in a rotating system have been analysed. The expressions for the mean velocity, mean temperature in the boundary layer and the mean skin friction, the mean rate of heat transfer on the plate are derived. The effects of magnetic parameterM, Hall parameterm, Schmidt number Sc, and Ekman numberE on the flow field, are discussed with the help of graphs and tables. 相似文献
16.
A. A. Raptis 《Astrophysics and Space Science》1982,86(1):43-53
An analysis of the two-dimensional flow of an incompressible, viscous binary fluid past an infinite, porous, vertical plate is presented under the following conditions: (i) the suction velocity is constant; (ii) the free stream oscillates in time about a constant mean; (iii) the plate moves in the upward direction in its own plane; (iv) the temperature of the plate is constant; (v) there are heat generation (absorption) in the fluid.Approximate solutions for the coupled non-linear equations are obtained for the velocity, temperature and their related quantities and the influence of the various parameters entering into the problem is discussed. 相似文献
17.
G. A. Georgantopoulos 《Astrophysics and Space Science》1979,63(2):491-501
An analysis of Rayleigh's problem (also Stokes's problem) for the flow of a viscous fluid (e.g. of a stellar atmosphere) past an impulsively started infinite, vertical porous limiting surface (e.g. of a star) with constant suction, when the free stream velocity oscillates in time about a constant mean, has been carried out. On solving the coupled non-linear equations in approximate way, expressions for the mean velocity, the mean temperature, the mean skin-friction and the mean rate of heat transfer, expressed in terms of Nusselt number, are obtained. The effects of Grashof numberG, Eckert numberE and Prandtl numberP, on these quantities, is discussed for the cases of an externally heating and cooling of the limiting surface, by the free convection currents, and the variations of them are shown graphically. 相似文献
18.
Unsteady hydromagnetic thermal boundary layer flow past a non-conducting infinite porous wall in presence of a transverse magnetic field is considered. The magnetic Reynolds number of the flow is taken to be small enough so that the induced magnetic field is negligible. It is assumed that the normal velocity of suction/injection at the wall varies att ?/12. Solution of the problem, in the form of power series, is obtained for two cases:
- When the wall temperature is the same as that of the free-stream, and
- When the difference in the temperatures of the wall and that of the free-stream varies as some power of time. The variations of the skin-friction, the temperature and the rate of heat transfer are shown graphically followed by a quantitative discussion.
19.
N. G. Kafousias N. D. Nanousis G. A. Georgantopoulos 《Astrophysics and Space Science》1979,64(2):391-399
This paper studies the effects of free convection currents on the flow field of an incompressible viscous fluid past an impulsively started infinite vertical porous limiting surface when the fluid is subjected to a suction with uniform velocity. An exact analysis of the problem is obtained with the aid of the Laplace transform technique and the expressions for the velocity field, temperature field and for their related quantities of skin friction and rate of heat transfer are given. The results thus obtained are discussed quantitatively for air and water. 相似文献
20.
P. C. Ram 《Astrophysics and Space Science》1989,158(2):189-195
An analysis of Hall effects on the hydromagnetic free convection resulting from the combined effects of thermal and mass diffusion of an electrically-conducting liquid passed an infinite vertical porous plate in a rotating frame of reference is carried out when a strong magnetic field is imposed in a plane which makes an angle with the normal to the plate. The expressions for the mean velocity, mean temperature in the boundary layer, and the mean skin-friction, the mean rate of heat transfer on the plate are derived. The influence of Hall currents on the flow is studied for various values of . 相似文献