SMOOTHED PARTICLE HYDRODYNAMICS SIMULATION OF EFFECTIVE THERMAL CONDUCTIVITY IN POROUS MEDIA OF VARIOUS PORE STRUCTURES

摘要

Heat conduction through a 2-D porous medium layer with complicated cylindrical or quadrangular pore structures is simulated using the smoothed particle hydrodynamics technique. Heat transfer paths are visualized at the micropore level, and the dependence of the effective thermal conductivity on the micropore structure is analyzed. As expected, heat always follows the path of least resistance through the porous structures. Globally, enhanced heat transfer paths tend to form in the porous medium having the smallest circular inclusions. The dependence of the effective thermal conductivity on the micropore structure is found to be closely related to the formation of enhanced heat transfer paths. For the porous medium with dispersed pore phase, the inclusion shape and size and the relative arrangement between inclusions do not have any particular effect on the relation between the effective thermal conductivity and the porosity. This finding is also well predicted by the effective medium theoretical (EMT) model with a flexible factor within the range 4.0-4.5. Owing to the significant effect of the pore-phase distribution, for the porous medium with continuous pore phase, the relation between the effective thermal conductivity and porosity can be predicted using the EMT model only if the flexible factor is taken for a value of 3.5.