Examination of the Thermal Equilibrium Assumption in Periodic Forced Convection in a Porous Channel

Abstract

The validity of the local thermal equilibrium assumption in the periodic forced convection porous channel flow is investigated analytically. Closed form expressions are presented for the temperatures of the fluid and solid domains and for the criterion that ensures the validity of the local thermal equilibrium assumption. It is found that four dimensionless parameters control the local thermal equilibrium assumption. These parameters are the porous domain void fraction ∈, the volumetric Biot number Bi, the dimensionless frequency ω, and the solid-to-fluid total thermal capacity ratio CR. The criterion that secures the validity of the local thermal equilibrium assumption within 5% error, is found to be...