The effect of local thermal non-equilibrium on forced convection boundary layer flow from a heated surface in porous media

Abstract

a b s t r a c tA steady two-dimensional forced convective thermal boundary layer flow in a porous medium is studied. It is assumed that the solid matrix and fluid phase which comprise the porous medium are subject to local thermal non-equilibrium conditions, and therefore two heat transport equations are adopted, one for each phase. When the basic flow velocity is sufficiently high, the thermal fields may be described accurately using the boundary layer approximation, and the resulting parabolic system is analysed both analytically and numerically. Local thermal non-equilibrium effects are found to be at their strongest near the leading edge, but these decrease with distance from the leading edge and local thermal equilibrium is attained at large distances.

Local thermal non-equilibrium effects in forced convection stagnation boundary layer flows in a porous medium: the Chebyshev collocation method for coupled system

“…Accordingly, the temperature of the fluid is not equal to the temperature of solid. Therefore, the heat transport equation is taken separately for each phase (in other words (6) is replaced by two energy equations) where the subscripts f and s are associated with the variables define for the fluid and solid in obvious way, h = h sf a v , h sf is volumetric interfacial heat transfer co-efficient, a v is specific surface of the porous medium (surface/ unit volume). The interesting work of Straughan [50,51] tackles closely related problem to the system (7)- (8) in which he develops mathematical equations for thermal convection in fluid-saturated porous medium under LTNE effects.…”

“…They even showed that when the infiltration fluid velocity is sufficiently large, the governing equations turn out to be a hyperbolic system that leads to a shock wave within the fluid phase. Celli et al [6] have shown for forced convection boundary layer flow and heat transfer in a porous medium under the LTNE regime that LTNE effects are strong near the leading boundary layer edge and gradually decrease away from the surface only to achieve the LTE. For the mixed convection boundary layer flow over a wedge embedded in a porous medium, Gogate et al [12] have shown that the LTNE effects are predominant for small inter-phase heat transfer rate and porosity scaled conductivity.…”

Study of the solidification process of a phase change material contained in a heat exchanger with the presence of a porous medium

“…This is the thermal equilibrium model. There are other researches that assume that the fluid and porous media do not have the same temperature [31][32][33][34].This is the non equilibrium thermal model.…”