The Influence Mechanism of Rock Fracture Roughness on Seepage Inertial Effect
To study the inertial effect evolution of fluid seepage in the rough fracture,the piecewise linear method was adopted to generate the rough fracture surface.Based on the lattice Boltzmann method,the interaction be-tween the rough wall surface and fluid was characterized using the half-way bounce-back scheme,and a nu-merical model was proposed to simulate the fluid flow in the rough fracture.The seepage velocity was mathemati-cally discretized using the finite difference method,and the viscous pressure drop and inertial pressure drop of rough fracture seepage fluid were obtained according to the momentum conservation equation.Finally,the effects of surface roughness,driving pressure and local eddy flow on the evolution of seepage inertial effect were studied.The results show that the inertial pressure drop is mainly controlled by the seepage velocity and its spatial varia-tion.The rough wall changes the magnitude and direction of fluid flow velocity,resulting in the inertial pressure drop.The cross-section average pressure drop exhibits a similar variation trend to the wall surface height.As the driving pressure of fracture seepage increases,the seepage inertial effect intensifies,leading to an increase in the average pressure drop,and the increase in average inertial pressure drop is particularly significant at the convex regions of the wall surface.The local eddy flow intensifies the kinetic energy loss,the pressure dissipation inside the eddy zone is dominated by the viscous pressure drop,and the inertial pressure drop gradually increases until it is close to the eddy boundary.
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