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1

Effect of electric field on dispersion of a solute in an MHD flow through a vertical channel with and without chemical reaction

Umavathi J. C., Kumar J. P., Gorla R. S. R., Gireesha B. J.

International Journal of Applied Mechanics and Engineering

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2016

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Vol. 21, no. 3

683--711

EN

The longitudinal dispersion of a solute between two parallel plates filled with two immiscible electrically conducting fluids is analyzed using Taylor’s model. The fluids in both the regions are incompressible and the transport properties are assumed to be constant. The channel walls are assumed to be electrically insulating. Separate solutions are matched at the interface using suitable matching conditions. The flow is accompanied by an irreversible first-order chemical reaction. The effects of the viscosity ratio, pressure gradient and Hartman number on the effective Taylor dispersion coefficient and volumetric flow rate for an open and short circuit are drawn in the absence and in the presence of chemical reactions. As the Hartman number increases the effective Taylor diffusion coefficient decreases for both open and short circuits. When the magnetic field remains constant, the numerical results show that for homogeneous and heterogeneous reactions, the effective Taylor diffusion coefficient decreases with an increase in the reaction rate constant for both open and short circuits.

2

MHD two-layered unsteady fluid flow and heat transfer through a horizontal channel between

Linga Raju T., Nagavalli M.

International Journal of Applied Mechanics and Engineering

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2014

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Vol. 19, no. 1

97--121

EN

An unsteady magnetohydrodynamic (MHD) two-layered fluids flow and heat transfer in a horizontal channel between two parallel plates in the presence of an applied magnetic and electric field is investigated, when the whole system is rotated about an axis perpendicular to the flow. The flow is driven by a constant uniform pressure gradient in the channel bounded by two parallel insulating plates, when both fluids are considered as electrically conducting, incompressible with variable properties, viz. different viscosities, thermal and electrical conductivities. The transport properties of the two fluids are taken to be constant and the bounding plates are maintained at constant and equal temperatures. The governing partial differential equations are then reduced to the ordinary linear differential equations using two-term series. Closed form solutions for primary and secondary velocity, also temperature distributions are obtained in both the fluid regions of the channel. Profiles of these solutions are plotted to discuss the effects of the flow and heat transfer characteristics, and their dependence on the governing parameters involved, such as the Hartmann number, rotation parameter, ratios of the viscosities, heights, electrical and thermal conductivities.

3

Hartmann two-fluid Poiseuille-Couette flow in an inclined channel

Umavathi J. C., Sridhar K. S. R.

International Journal of Applied Mechanics and Engineering

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2009

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Vol. 14, no 2

539-557

EN

A numerical and analytical study of a two fluid magnetohydrodynamic Poiseuille-Couette flow in an inclined channel is investigated. The fluids in both the regions are incompressible, electrically conducting and the transport properties are assumed to be constant. The channel walls are assumed to be electrically insulating. Separate solutions for each fluid are obtained and these solutions are matched at the interface using suitable matching conditions. The governing equations of motion are solved analytically and are valid for small Eckert numbers and numerically valid for large . Solutions for large show a marked change on the velocity and temperature profiles. The results are presented graphically for various Hartmann number, Grashof number, angle of inclination and also for various ratios. It is found that the flow can be controlled effectively by a suitable choice of values of ratios of electrical conductivities, widths, viscosities and thermal conductivities.

4

Oscillatory hartmann two-fluid flow and heat transfer in a horizontal channel

Umavathi J. C., Mateen A., Chamkha A. J., Al-Mudhaf A.

International Journal of Applied Mechanics and Engineering

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2006

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Vol. 11, no 1

155-178

EN

An unsteady Hartmann flow of two immiscible fluids through a horizontal channel with time-dependent oscillatory wall transpiration velocity is investigated. One of the fluids is assumed to be electrically conducting while the other fluid and the channel walls are assumed to be electrically insulating. Separate solutions for each fluid are obtained and these solutions are matched at the interface using suitable matching conditions. The partial differential equations governing the flow and heat transfer are transformed to ordinary differential equations and closed-form solutions are obtained in both fluids' regions of the channel for steady and unsteady conditions. The closed-form results are presented graphically for various values of the Hartmann number, frequency parameter, periodic frequency parameter viscosity and conductivity ratios as well as the Prandtl number to show their effect on the flow and heat transfer characteristics.