LOCAL THERMAL NONEQUILIBRIUM VISCOUS DISSIPATIVE COUETTE FLOW IN A POROUS MEDIUM

Abstract

A local thermal nonequilibrium Couette flow in a saturated porous medium, subjected to uniform heat flux, is investigated, where concern is focused on the effects of viscous dissipation. The temperature field is derived analytically in terms of Brinkman number (Br) and porous medium shape factor applied to conditions where the local thermal nonequilibrium effect is profound. Contrary to pressure-driven flow in porous medium, viscous dissipation has a more significant effect on the transverse temperature variation of a porous medium with high porous medium shape factor due to the shearing force on the moving wall. A comparison with the local thermal equilibrium model reveals that such an effect is heightened as the thermal resistance to heat conduction in fluid at the heated boundary becomes greater. The computed Nusselt number (Nu) indicates a reversal in the trend of declining Nu with increasing Br as the porous medium shape factor drops below one. As Br is a function of characteristic gap size, this study also gauges the effect of characteristic length scale of the parallel channel on the temperature field. The resulting fluid and solid temperature fields depend strongly on the characteristic gap size between parallel plates, while viscous dissipation intensification overrides the convection enhancement effect in microscale applications.