Numerical Simulations of Heat Transfer in Porous Media with Effect of Heterogeneities(Heat and Mass Transfer)

Numerical simulations are employed to investigate the heat transfer and fluid flow in an inhomogeneous porous medium. The permeability heterogeneity, characterized by a correlation length and variance, are seen to have strong effect on both the flow and heat transfer. The velocity fluctuation generated by permeability heterogeneity has the tendency to alter the flow features and orientation predominantly at the scale of the correlation length. For an isotropic permeability distribution, the most pronounced effect of flow alternation and fluctuation is observed at intermediate correlation length, which agrees with previous findings, thus leads to the best performance of convective heat transfer. In a permeability field with anisotropic correlation length, larger correlation length along the stream-wise direction makes the velocity fluctuation oriented more likely parallel to the main averaged velocity, and weakens the transverse transport effects. Therefore, better heat transfer performance is found if larger correlation length is aligned along the transverse direction. The simulations also show better heat transfer effect as the variance of the permeability field or global flow rate increases.