This study investigates the critical agents that cause non-Darrian flow in porous media. Four porous media different in morphology but similar in topology were studied numerically. By varying the throat diameters, the distinct roles of pores and throats in total dissipation were investigated using direct numerical simulation. Forchheimer model was selected to analyze the non-Darcian flow. In our simplified geometry, the ratio KappKD can best be correlated by non-Darcy effect (E). Total dissipation is directly related to the porous medium resistance against fluid flow. The energy dissipated in pores and throats was calculated by summing the dissipation in each computational segment. Pores are more prone to disobey the Darcy model than throats due to irregularity in fluid flow, and they are introduced as the cause of Darcy-model cessation. By increasing the pore-to-throat ratio, the non-Darcian flow in the pores begins sooner. The results show that the energy dissipation due to eddies is negligible. The dissipation in pores and throats was simulated through separate power-law equations, and their exponents were also extracted. The exponent for the pore body is equal to two when the viscous forces are dominant, and it increases by increasing the inertia force. The dissipation due to pore bodies is more apparent when the size of pore and throats are of the same order of magnitude. The relative losses of pore body increase as the velocity increases, in contrast to throats.

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