An investigation of variants within the porous media transport models is presented in this work. Four major categories in modeling the transport processes through porous media, namely constant porosity, variable porosity, thermal dispersion, and local thermal nonequilibrium, are analyzed in detail. The main objective of the current study is to compare these variances in models for each of the four categories and establish conditions leading to convergence or divergence among different models. To analyze the effects of variants within these transport models, a systematic reduction and sensitivity investigation for each of these four aspects is presented. The effects of the Darcy number, inertia parameter, Reynolds number, porosity, particle diameter, and the fluid-to-solid conductivity ratio on the variances within each of the four areas are analyzed. It is shown that for some cases the variances within different models have a negligible effect on the results while for some cases the variations can become significant. In general, the variances have a more pronounced effect on the velocity field and a substantially smaller effect on the temperature field and Nusselt number distribution. *[S0022-1481(00)02602-5]*

*Convective Heat and Mass Transfer in Porous Media*, S. Kacac, B. Kilikis, F. A. Kulacki, and F. Arnic, eds., Kluwer Academic, Dordrecht, pp. 289–328.

*Principles of Heat Transfer in Porous Media*, 2nd Ed., Springer-Verlag, New York.

*Convection in Porous Media*, 2nd Ed., Springer-Verlag, New York.

*Transport Phenomena in Porous Media*, D. B. Ingham and I. Pop, eds., Pergamon, England, pp. 313–329.