Thermal Equilibrium in Transient Forced Convection Porous Channel Flow

The validity of the local thermal equilibrium assumption in the transient forced convection channel flow is investigated numerically. Axial conduction in both fluid and solid domains is included. It is found that five dimensionless parameters control the local thermal equilibrium assumption. These parameters are the thermal diffusivity ratio αR, the volumetric Nusselt number Nu, the dimensionless channel length ξmax, Peclet number Pe, and the solid to fluid total thermal capacity ratio CR. The qualitative and quantitative aspects of the effects of these five parameters on the channel thermalization time are investigated.