Computational fluid dynamics study to develop pressure drop correlations for fluid flow through high porosity graphite foam as a function of microstructure parameters
In order to better understand the effect of microstructure parameters on forced convection pressure losses in graphite foam, correlations were developed for the permeability and form coefficient that appear in the porous media momentum equation. Computational fluid dynamics simulations were carried out for laminar, periodic air flow through an idealized pore geometry. Simulations were performed for foams with a wide range of pore diameter and inter-pore window diameter and porosity ranging from 0.75 to 0.85. The results of the simulations are validated using experimental results in literature within a certain range of values of the ratio of pore diameter to inter-pore window diameter. Expressions for the permeability and form coefficient as functions of pore diameter, inter-pore window diameter and porosity are developed using the results of the numerical simulations. To develop the permeability expression, an analogy was drawn to fully developed laminar flow through a pipe with an added term to account for the effect of porosity. To develop the form coefficient expression, it was assumed that the inertial effects on pressure drop are dominated by the ratio of the pore diameter to inter-pore window diameter. Terms to account for the effect of porosity were also added. The expressions are applicable within the ranges of Reynolds number, porosity, and pore diameter to inter-pore window diameter values that were validated. The proposed expressions are intended to be used in future studies related to the application of graphite foam in convective heat transfer applications.