NUMERICAL SIMULATION OF FLUID FLOW THROUGH METALLIC FOAMS: A GENERAL CORRELATION FOR DIFFERENT LENGTH SIZES AND PORE CHARACTERISTICS

In the present research work, numerical simulations are performed to investigate the effect of structural parameters on fluid flow in metallic foams by meshing computed micro-tomography images. This study tries to reveal the main hydrodynamic characteristics of foams with different length sizes (0.4 to 40 mm) and various physical specifications such as different porosities (76%-96%) and pore diameter sizes (100-500 ym). Based on the Ergun equation, the pressure gradient results obtained from Delta P/L = alpha v + beta v(2) showed that the linear (alpha) and nonlinear (beta) coefficients were strongly dependent on the geometry of the porous medium. Moreover, the results indicated that the porosity variations can greatly affect fluid flow in a constant pore diameter. However, in constant porosity, the change in pore diameter did not have a significant effect on fluid flow. In this investigation the effect of foam size was observed with increasing length (i.e., it could be resized only in the direction of fluid flow); the pressure gradient decreased and reached a specific value (in a certain length, called the critical length) and then was constant. Also, it concluded that the porosity variations had no effect on this length, but the change in pore diameter had a significant effect on it. Finally, a correlation for improving the Ergun equation was obtained in terms of parameters such as the porosity, pore diameter, tortuosity, and length, which appeared to offer reasonable precision for studying and predicting air flow on a large scale in practical engineering problems.