考虑动态流体网格的颗粒-流体耦合算法

Particle-Fluid Coupling Algorithm Considering Dynamic Fluid Mesh

传统颗粒-流体耦合算法难以考虑流体动态边界问题,在模拟大变形案例时因流固边界不匹配易造成计算误差,影响结果的准确性.针对该问题,引入流体网格动态更新方法,推导动网格下的达西渗流方程和颗粒-流体相互作用方程,在离散元商业软件PFC 2D基础上,开发了考虑流体动网格的颗粒-流体耦合算法.将该算法用于模拟饱和土不排水剪切双轴试验,通过与常体积法的结果对比,验证了该方法的有效性.最后,采用该算法模拟了不同围压下的不排水双轴试验,计算结果的规律与室内试验具有较好的一致性.该算法考虑了流体动网格的问题,在模拟大变形下的三轴压缩试验、一维固结试验等案例时可获得相适应的流固边界,有助于提高模拟精度,因此可为类似研究提供参考.

It is generally difficult to consider the fluid dynamic boundary problem in the traditional particle-fluid coupling algorithm,causing calculation errors owing to the mismatching of the fluid-solid boundary and affecting the accuracy of the results in the modeling of large deformation issues.In view of this problem,the dynamic updating method of fluid mesh is introduced and Darcy’s seepage equation and the particle-fluid interaction equation in dynamic mesh are derived.Based on the discrete element commercial software PFC 2D,the particle-fluid coupling algorithm considering dynamic fluid mesh is developed.The proposed algorithm is applied to simulate the undrained shear biaxial test of saturated soil.The comparison result with the constant volume method verifies the effectiveness of the developed algorithm.Finally,the algorithm is used to simulate the undrained biaxial tests at different confining pressures.The law of the calculated results agrees well with that of the laboratory tests.By considering the problem of fluid dynamic boundary,the developed algorithm can obtain the fluid-solid boundary matching in the simulation of triaxial compression test and one-dimensional consolidation test or other cases in large deformations,which can help to improve the simulation accuracy and offer a theoretical reference for similar studies.