Effect of transverse magnetic field on heat transfer to an electrically conducting and thermal radiating fluid flowing in a parallel-plate channel

Zusammenfassung Der Einfluss eines magnetischen Feldes auf die Wärmeübertragung in einer ausgebildeten laminaren Strömung einer elektrisch leitenden, wärmestrahlenden, zähen und inkompressiblen Flüssigkeit zwischen zwei unendlichen parallelen Platten wird untersucht. Ein konstantes äusseres magnetisches Feld wirkt in der Richtung senkrecht zu den Platten und der Strömungsrichtung. Die auf einer konstanten Temperatur gehaltenen Kanalwände sollen Wärme ausstrahlen und diffus reflektieren.Die Temperaturverläufe wurden für einige Werte der interessierenden Parameter und für das ganze Gebiet der Hartmannschen Zahl numerisch gerechnet. Die entsprechenden Kennwerte der Wärmeübertragung zwischen den Kanalwänden und der Flüssigkeit sind im Text tabellarisch angegeben. Das Magnetfeld vergrössert sowohl die Wärmeübertragung durch Leitung als auch durch Strahlung. Die Vergrösserung ist jedoch gering.

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Work done under auspices of U.S. Atomic Energy Commission.     

Unsteady couette flow of a conducting fluid between two parallel plates under a transverse magnetic field—I

The unsteady Couette flow of a viscous incompressible fluid between two parallel plates in the presence of a transverse magnetic field is considered. Using the Laplace transform technique, expressions for the velocity of the fluid and the intensities of the electrical and magnetic fields are obtained in two cases; when the plates are non-conducting and when they are perfectly conducting.     

Unsteady couette flow of a conducting fluid between two parallel plates under a transverse magnetic field—II

The effect of a sudden change in magnetic field and pressure gradient on a steady Couette flow of a viscous incompressible fluid between two parallel plates in the presence of a transverse magnetic field is considered. Expressions for the velocity of the fluid in the disturbed flow, the intensities of the electrical and magnetic fields are obtained in two cases when the plates are non-conducting and when they are perfectly conducting.     

Flow of an electrically conducting fluid past a porous flat plate in the presence of a transverse magnetic field

Zusammenfassung Für die Strömung einer inkompressiblen, zähen, elektrisch leitenden Flüssigkeit über eine poröse Platte werden die Gleichungen vonNavier undStokes, vonMaxwell und die Wärmeübertragungsgleichung integriert. Dabei wird vorausgesetzt, dass Flüssigkeit aus der porösen Platte austritt oder durch sie abgesogen wird. Man findet, dass sowohl die Geschwindigkeiten als auch die Schubspannungen mit steigender magnetischer Druckzahl für Absaugen und Ausblasen anwachsen. Das induzierte Feld an der Plattenoberfläche wird kleiner, wenn die Ausblasegeschwindigkeit abnimmt. Für den Grenzfall unendlicher elektrischer Leitfähigkeit wächst der Wärmeübergang mit der magnetischen Druckzahl im Falle des Ausblasens.     

Radial flow of a viscous,incompressible, electrically conducting fluid between two stationary,porous discs in the presence of transverse magnetic field

The problem of incompressible, electrically conducting viscous laminar flow between two non-conducting coaxial discs is studied, in the presence of transverse magnetic field of uniform intensity, when there is constant injection or suction at the discs. The problem is interesting both mathematically and physically. The solution, for small suction or injection, has been obtained for highly viscous fluid. The velocity profiles have also been drawn graphically.     

On the flow of an electrically conducting,incompressible fluid near an accelerated plate in the presence of a parallel plate,under transverse magnetic field

This paper deals with hydromagnetic flow of an electrically conducting, incompressible viscous fluid near an accelerated flat, non-conducting plate, in the presence of another parallel plate, when there is a transversely applied magnetic field. Induced magnetic field is neglected in comparison with the applied magnetic field. Laplace transform techniques are used. The equations are integrated by applying residue principle, and expressions for velocity profiles and skin-friction at both plates are derived for different values of Hartmann number M. It is observed that, with the increase of the value of the Hartmann number M, the velocity profiles are flattened, the shear stress at the stationary plate decreases, as the value of the time T and Hartmann number M increases, but the shear stress at the accelerated plate increases directly in proportion with the increase in time and Hartmann number.     

Stratified rotating viscous flow between two disks under transverse magnetic field

Proceedings - Mathematical Sciences -     

Heat transfer to power-law fluids in thermal entrance region with viscous dissipation for constant heat flux conditions

An analytical solution of the heat transfer problem with viscous dissipation for non-Newtonian fluids with power-law model in the thermal entrance region of a circular pipe and two parallel plates under constant heat flux conditions is obtained using eigenvalue approach by suitably replacing one of the boundary conditions by total energy balance equation. Analytical expressions for the wall and the bulk temperatures and the local Nusselt number are presented. The results are in close agreement with those obtained by implicit finite-difference scheme. It is found that the role of viscous dissipation on heat transfer is completely different for heating and cooling conditions at the wall. The results for the case of cooling at the wall are of interest in the design of the oil pipe line.     

Heat transfer in a visco-elastic fluid past a stretching sheet with viscous dissipation and internal heat generation

This paper deals with the study of heat transfer characteristics in the laminar boundary layer flow of a visco-elastic fluid over a linearly stretching continuous surface with variable wall temperature subjected to suction or blowing. The study considers the effects of frictional heating (viscous dissipation) and internal heat generation or absorption. An analysis has been carried out for two different cases of heating processes namely: (i) Prescribed surface temperature (PST) and (ii) Prescribed wall heat flux (PHF) to get the effect of visco-elastic parameter for various situations. Further increase of visco-elastic parameter is to decrease the skin friction on the sheet. The solutions for the temperature and the heat transfer characteristics are obtained in terms of Kummers function. Received: June 16, 2004; revised: February 8, 2005     

Weak fluctuation modes of an electrically and thermally conducting viscous compressible flow in a homogeneous magnetic field

Zusammenfassung Eine Perturbationstheorie erster Ordnung zeigt, daß die Gleichungen, die die Bewegung eines elektrisch und thermisch leitenden zähen kompressiblen Strömungsfeldes bestimmen, welches endliche elektrische Leitfähigkeit hat, vier verschiedene Typen von Störungsfeldern enthalten kann; diese werden von vier unabhängigen partiellen Differentialgleichungen bestimmt. Die drei ersten Typen sind: Wirbel-Stromdichte- und magnetisch-akustische Wellen-Typen. Sie sind hyperbolischer Art und pflanzen sich nicht isotrop als Wellen fort. Der vierte Typ ist ein Entropie-Typ, der sich nicht ausbreitet und der von einer parabolischen Gleichung bestimmt wird. Jeder dieser verschiedenen Typen kann nicht weiter zerlegt werden wie im Falle inkompressibler Strömung. Zusätzlich wird gezeigt, daß die magnetisch-akustischen Wellen im Falle endlicher elektrischer Leitfähigkeit neue und interessante Eigenschaften besitzen.     

Asymptotic model for free surface flow of an electrically conducting fluid in a high-frequency magnetic field

We study the behaviour of a layer of an electrically conducting inviscid incompressible fluid in a high-frequency alternating magnetic field. We derive nonlinear asymptotic equations governing the evolution of the fluid layer in the high-frequency limit. As a test for the model, we consider the linearised stability problem for an infinite planar free surface of a layer of finite depth.     

Analytical solution for the unsteady MHD flow of a viscous fluid between moving parallel plates

Two-dimensional unsteady MHD flow of a viscous fluid between two moving parallel plates is considered. We allow the plates to move together as well as apart: When the plates move together it corresponds to squeezing flow problem. The governing Navier–Stokes equations for the flow are reduced to a fourth order nonlinear ODE and analytical solutions are obtained for the ODE via the homotopy analysis method. We show that the flow is strongly influenced by the strength of the magnetic field and the density of the fluid. Furthermore, an error analysis for the obtained solutions is provided.     

Toroidal oscillations of a spherical mass of viscous conducting fluid in a uniform magnetic field

Zusammenfassung Es werden die toroidalen Schwingungen einer flüssigen Kugel in einem konstanten Magnetfeld betrachtet. Nach [2] ist bekannt, dass das Spektrum der Eigenwerte für vollkommen leitende Flüssigkeit kontinuierlich ist. Hier wird aufgezeigt, dass für endliche Leitfähigkeit ein diskretes Spektrum entsteht und dass der diskrete Charakter erhalten bleibt, wenn die Leitfähigkeit nach Unendlich strebt. In diesem Grenzfall konzentriert sich die Schwingung auf die Symmetrieachse.     

Effect of viscous dissipation on natural convection flow between vertical parallel plates with time-periodic boundary conditions

This article investigates the natural convection flow of viscous incompressible fluid in a channel formed by two infinite vertical parallel plates. Fully developed laminar flow is considered in a vertical channel with steady-periodic temperature regime on the boundaries. The effect of internal heating by viscous dissipation is taken into consideration. Separating the velocity and temperature fields into steady and periodic parts, the resulting second order ordinary differential equations are solved to obtain the expressions for velocity, and temperature. The amplitudes and phases of temperature and velocity are also obtained as well as the rate of heat transfer and the skin-friction on the plates. In presence of viscous dissipation, fluids of relatively small Prandtl number has higher temperature than the channel plates and as such, heat is being transferred from the fluid to the plate.     

Unsteady Couette flow of viscous fluid under a non-uniform magnetic field

The aim of this letter is to construct the analytic solution for unsteady Couette flow in the presence of an arbitrary non-uniform applied magnetic field. The flow is induced by a generalized velocity given to the lower plate. The perturbed eigenfunction expansion method is employed to develop a series solution for small magnetic field.     

Combined effect of magnetic field and heat absorption on unsteady free convection and heat transfer flow in a micropolar fluid past a semi-infinite moving plate with viscous dissipation using element free Galerkin method

The fully developed electrically conducting micropolar fluid flow and heat transfer along a semi-infinite vertical porous moving plate is studied including the effect of viscous heating and in the presence of a magnetic field applied transversely to the direction of the flow. The Darcy-Brinkman-Forchheimer model which includes the effects of boundary and inertia forces is employed. The differential equations governing the problem have been transformed by a similarity transformation into a system of non-dimensional differential equations which are solved numerically by element free Galerkin method. Profiles for velocity, microrotation and temperature are presented for a wide range of plate velocity, viscosity ratio, Darcy number, Forchhimer number, magnetic field parameter, heat absorption parameter and the micropolar parameter. The skin friction and Nusselt numbers at the plates are also shown graphically. The present problem has significant applications in chemical engineering, materials processing, solar porous wafer absorber systems and metallurgy.     

Effect of heat transfer on the peristaltic flow of an electrically conducting fluid in a porous space

This work is aimed at describing the heat transfer on the peristaltic motion in a porous space. An incompressible and magnetohydrodynamic (MHD) viscous fluid is taken in an asymmetrical channel. Expressions of dimensionless stream function and temperature are obtained analytically by employing long wavelength and low Reynolds number assumptions. The influence of various parameters of interest is seen through graphs on pumping and trapping phenomena and temperature profile.     

Flow of an electrically conducting non-newtonian fluid between two rotating coaxial cones in the presence of external magnetic field due to an axial current

Bhatnagar and Rathna (Quar. Journ. Mech. Appl. Maths., 1963,16, 329) investigated the flows of Newtonian, Reiner-Rivlin and Rivlin-Ericksen fluids between two rotating coaxial cones. In case of the last two types of fluids, they predicted the breaking of secondary flow field in any meridian plane. We find that such breaking is avoided by the application of a sufficiently strong azimuthal magnetic field arising from a line current along the axis of the cones.