Nanigopal Datta

Hall effects on unsteady couette flow

Abstract Hall effects on Couette flow of an electrically conducting fluid between two parallel plates for both the cases of impulsive as well as uniformly accelerated motion of one of the plates is discussed. Expressions for the shear stress components are obtained in terms of two non-dimensional parameters, the Hartmann number and the Hall parameter. It is found that for the case of impulsive as well as accelerated motion of one of the plates, the magnitude of the shear stress component due to the primary flow decrease whereas that due to the secondary flow increase with increase in Hall parameter.

Unsteady heat transfer to pulsatile flow of a dusty viscous incompressible fluid in a channel

Abstract The problem of unsteady heat transfer to pulsatile flow of a dusty fluid in a parallel plate channel has been studied. It is observed that the unsteady part of the fluid velocity as well as of the particle phase velocity has a phase lag which increases with increase of φ, i.e. the volume fraction of the particles. The steady part of the heat transfer at the hotter plate decreases with increase of φ whereas it increases with increase of φ at the colder plate. The amplitude of the unsteady part of the heat transfer at both the plates decreases with increase of φ.

Hall effects on hydromagnetic convective flow through a channel with conducting walls

Abstract Hall effects on the combined free and forced convective fully-developed flow in a parallel plate channel with perfectly conducting walls has been considered. An exact solution of the governing equations has been obtained. It is found that in contrast with the result for non-conducting plates, the shear stress components depend on both the Hartmann number and the Hall parameter even in the absence of buoyancy forces. The heat transfer at both the plates decrease with increase in either Grashof number or Hall parameter.

Flow and heat transfer in the hydromagnetic ekman layer on a porous plate with hall effects

Abstract Flow in the Ekman layer of a conducting liquid past an infinite porous plate is investigated when the liquid is permeated by a transverse magnetic field and the Hall effects are taken into account. It is found that asymptotic solution exists both in the presence of suction or blowing at the plate. For fixed magnetic and suction parameters, the skin friction of the primary flow increases with increase in the Hall parameter ωτ, while that for the secondary flow first increases, reaches a maximum and then decreases with increase in ωτ. Steady distribution of temperature in the flow exists only for suction at the plate and for large Eckert numbers, heat flows from the liquid to the wall even if the wall temperature is higher than that of the ambient stream.

Hall effects on combined free and forced convective hydromagnetic flow through a channel

Abstract Hydromagnetic free and forced convection in a parallel plate channel permeated by a transverse magnetic field has been considered taking Hall effects into account. When there is a uniform axial temperature variation along the walls, the primary flow shows incipient flow reversal at the upper plate for an increase in temperature along that plate. Similarly flow reversal at the lower plate occurs for a decrease in temperature along that plate. Hall currents are found to exert a destabilizing influence on the flow. The skin-friction for the cross-flow increases with the Hall parameter. The induced magnetic field and the heat transfer characteristics in the flow are also determined.

Unsteady natural convection of a dusty fluid in an infinite rectangular channel

Abstract Natural convection of a dusty fluid in an infinite rectangular channel with differentially heated vertical walls and adiabatic horizontal walls has been studied. The problem has been solved using a combination scheme of central and second upwind differencing. It is seen that the heat transfer rate decreases with an increase of mass concentration of dust particles, but it increases with an increase of the Rayleigh number.

Effect of wall conductances on hydromagnetic convection of a radiating gas in a vertical channel

Abstract An exact solution has been found for the fully-developed convective flow of an electrically conducting fluid between two vertical thermally and the electrically conducting walls, under a transverse magnetic field. It is found that with the increase of electrical conductance of the walls, the velocity, the temperature, the flow rate and the rate of heat transfer decrease and the magnetic field increases. But the velocity, the magnetic field, the flow rate, the rate of heat transfer decrease and the temperature increases with the increase of thermal conductance of the walls.

Hall effects on free convection between vertical parallel plates

SommarioSi analizzano gli effetti nella convezione libera laminare idromagnetica completamente sviluppata in un canale verticale a facce parallele con riscaldamento asimmetrico. Si discutono gli effetti della corrente di Hall e del rapporto delle differenze di temperatura alla parete sulla velocità e sul campo magnetico. Con laumentare del parametro di Hall, la risultante sollecitazione di taglio sulla parete più fredda aumenta, mentre quella sulla parete più calda diminuisce; inoltre, si verifica un cambiamento di segno del numero di Nusselt a entrambe le pareti.SummaryHall effects on the hydromagnetic fully-developed laminar free convection in a vertical parallel plate channel with asymmetric heating is analyzed. The effects of Hall current and the wall temperature difference ratio on the velocity and the magnetic field is discussed. The resultant shear stress at the cooler wall increases while that at the hotter wall decreases with increase in Hall parameter. With increase in Hall parameter, there occurs a change of sign in the Nusselt number at both the plates.

Unsteady flow in the Ekman layer of an elastico-viscous liquid

The transient flow in the Ekman layer of an elastico-viscous liquid near a flat plate is discussed. Initially the fluid and the plate were rotating together and the plate then suddently starts moving with a uniform velocity in its own plane relative to the rotating frame of reference. It is shown that the ultimate steady state is reached through decay of inertial oscillations whose frequency decreases with increase in the elastic parameter.