The heterogeneous fracture geometry induced by the presence of roughness and shearing complicates the fracture flow. This paper presents a numerical investigation of the non-Darcian flow characteristics of rough-walled fractures during shear processes. A series of fracture flow simulations were performed on four types of fractures with different joint roughness coefficients (JRCs), and the different shear displacements were imitated by degrees of mismatch on two fracture surfaces. The results show that the disorder of fracture geometries and the increase in flow rate are the main causes for the emergence of an eddy flow region, which can significantly reduce the fracture conductivity and change the fracture flow from linear to nonlinear. The Forchheimer equation provides a good model for the nonlinear relationship between the hydraulic gradient and the flow rate in the fracture flow. When the shear displacement or JRC increased, the linear permeability coefficient kv decreased, while the nonlinear coefficient β increased. A three-parameter equation of β was used to examine the inertial effect induced by the fracture roughness JRC and the variation coefficient of aperture distribution σs/em. The critical Reynolds number was a combined effect of aperture, viscous permeability, and inertial resistance, assuming the flow becomes non-Darcian when the inertial part is greater than 10%.

中文翻译：

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剪切对粗糙壁裂缝非达西流体流动特性的影响

由粗糙度和剪切力的存在引起的非均质裂缝几何形状使裂缝流动复杂化。本文对剪切过程中粗糙壁裂缝的非达西流动特性进行了数值研究。对具有不同接头粗糙度系数（JRC）的四种裂缝进行了一系列裂缝流动模拟，并通过两个裂缝表面的失配程度来模拟不同的剪切位移。结果表明，裂缝几何形态的紊乱和流速的增加是涡流区出现的主要原因，涡流区可显着降低裂缝导流能力，使裂缝流由线性变为非线性。Forchheimer 方程为压裂流中水力梯度和流速之间的非线性关系提供了一个很好的模型。当剪切位移或JRC增大时，线性渗透系数kv减小，而非线性系数β增大。β的三参数方程用于检验由断裂粗糙度JRC和孔径分布变异系数σs/em引起的惯性效应。临界雷诺数是孔径、粘性渗透率和惯性阻力的综合效应，假设当惯性部分大于 10% 时流动变为非达西。β的三参数方程用于检验由断裂粗糙度JRC和孔径分布变异系数σs/em引起的惯性效应。临界雷诺数是孔径、粘性渗透率和惯性阻力的综合效应，假设当惯性部分大于 10% 时流动变为非达西。β的三参数方程用于检验由断裂粗糙度JRC和孔径分布变异系数σs/em引起的惯性效应。临界雷诺数是孔径、粘性渗透率和惯性阻力的综合效应，假设当惯性部分大于 10% 时流动变为非达西。