G. J. Tzivanidis

Free convection and mass transfer flow through a porous medium bounded by an infinite vertical limiting surface with constant suction

Abstract Steady two-dimensional free convection and mass transfer flow, of an incompressible viscous fluid through a porous medium bounded by a vertical infinite limiting surface (plane wall) is considered. Expressions for the velocity, temperature, concentration and the rate of heat transfer are obtained. Effects of Gr (Grashof number), Gm (modified Grashof number) and permeability K of the porous medium on the velocity and rate of heat transfer are discussed when the surface is subjected to a constant suction velocity.

Hydromagnetic free convection flow through a porous medium between two parallel plates

Abstract Steady hydromagnetic free convective flow of a conducting fluid through a porous medium bounded by two parallel plates is considered and effects of G (Grashof number) and the K (permeability parameter) on the velocity field are discussed.

Free convection flow through a porous medium bounded by a vertical surface

Steady two-dimensional free convection flow through a porous medium bounded by a vertical infinite surface is considered. Expressions for the velocity, temperature and the rate of heat transfer are obtained. Effects of G (Grashof number) and K (permeability parameter) on the velocity and the rate of heat transfer are discussed.

Hydromagnetic free convection flow past an accelerated vertical infinite plate with variable suction and heat flux

Abstract This paper provides an analysis of the effects of a uniform transverse magnetic field on the free-convection flow of a viscous incompressible and electrically conductive fluid past an accelerated vertical infinite plate with variable suction or injection and heat flux. The magnetic Reynolds number is assumed small so that the induced magnetic field is considered negligible. Solutions of the equations governing the flow are obtained with the help of the power series when the prandtl number P is equal to one. Expressions are given for the velocity field, the temperature field and the skin-friction. The results obtained are discussed quantitatively in the last section of this paper.

Effects of mass transfer, free-convection currents and heat sources on the Stokes' problem for an infinite vertical plate

An exact analysis of the effects of heat sources, mass transfer and free-convection currents on the flow past an impulsively started vertical plate is investigated. Closed-form solutions to the velocity and temperature field have been derived by using Laplace transform and expressions are given for the Skin-friction and the rate of heat transfer. Variations of the above quantities are presented graphically, and the paper is concluded with a quantitative discussion.

Unsteady flow through a porous medium with the presence mass transfer

Abstract Unsteady flow through a very porous medium with the presence mass transfer is considered. The porous medium is bounded by a vertical plate and this plate absorbs the fluid with a constant velocity. Also the free stream velocity of the fluid vibrates about a mean constant value. The influences of the permeability parameter and the modified Grashof number on the velocity field are discussed.

Mass transfer effects on the flow past an accelerated infinite vertical plate with variable heat-transfer

SummaryAn analysis of the mass transfer in a unsteady two-dimensional flow past an accelerated infinite vertical plate has been carried out under the following conditions: (1) The heat-transfer is varied at the plate (2) the non-dimensional timet is small and (3) Prandtl and Schmidt number is equal to one.Approximate solutions for the coupled non-linear equations are obtained for the velocity and temperature and shown on figures. The numerical values of the skin friction and the rat of heat transfer are entered in a table.ZusammenfassungEs wird der Massentransport in einer instationären zweidimensionalen Strömung längs einer beschleunigten unendlich ausgedehnten vertikalen Platte unter den folgenden Bedingungen ermittelt: (1) der Wärmeübergang ist variabel auf der Platte, (2) die dimensionslose Zeitt ist klein, (3) die Prandtl- und die Schmidt-Zahl sind 1.Für das gekoppelte nichtlineare Differentialgleichungssystem werden Näherungslösungen für Geschwindigkeit und Temperatur bestimmt und in Diagrammen dargestellt. Die numerischen Werte für die Oberflächenreibung sowie für den Wärmeübergang werden in einer Tabelle angegeben.

Free convection effects on the hydromagnetic oscillatory flow in the stokes problem past an infinite porous vertical limiting surface with constant suction, II

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.

Hydromagnetic free convection effects on the oscillatory flow of an electrically conducting rarefied gas past an infinite vertical porous plate

Abstract Unsteady two-dimensional free convection flow of an electrically conducting, viscous, incompressible rarefied gas, past an infinite vertical porous plate in the presence of a transverse magnetic field is studied. The freestream 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 not taken to be small enough, so that the induced magnetic field is not negligible. The plate temperature is constant and the difference between the temperature of the plate and the freestream is moderately large causing the free convection currents. The flow field is described by a nonlinear coupled system of equations subjected to the first-order velocity slip and temperature jump boundary conditions. With viscous dissipative heat and Joule heating taken into account, approximate solutions of the problem are obtained for the velocity, temperature and induced magnetic field, as well as, for the related to them quantities of the skin friction, rate of the heat transfer and electric current density.

Mass transfer and free convective MHD flow past an accelerated vertical porous plate

The effects of variable suction/injection on the unsteady two-dimensional free convective flow with mass transfer of an electrically conducting fluid past a vertical accelerated plate in presence of a transverse magnetic field is considered. Solutions of the equations governing the flow are obtained with the help of the power series. The paper is concluded with a discussion of the results obtained.ZusammenfassungIn dieser Arbeit werden die Wirkungen verÄnderlicher Absaugung/Ausblasung auf die instationÄre zweidimensionale freie Strömung mit Stoffübertragung eines elektrisch leitenden Fluids an einer senkrecht beschleunigten Wand mit magnetischem Querfeld betrachtet. Lösungen erhÄlt man mit Hilfe von PotenzansÄtzen. Die Ergebnisse werden diskutiert.