软球模型在颗粒流全尺度模拟中的验证和分析

摘要

Towards solving the dry collision problem occurred in fully‐resolved simulation of particulate flow ,soft‐sphere collision model was added to the multi‐direct forcing and immersed boundary method . Applicability and accuracy of soft‐sphere model for solving dry collision in fully‐resolved simulation were verified by two typical cases:One was the bouncing motion of a sphere;the other was ball slipping on a rough surface .Parameters sensitivity analysis to soft‐sphere model shows that the precision for collision simulation is improved if time step reduces ;small spring stiffness increases the characteristic collision time such that limitations on fully‐resolved simulation can be reduced;mesh size and normal restitution coefficient have little impact on solving precision . Fully‐resolved simulation of a library‐scale gas‐solid fluidized bed shows that our numerical method can be used to deal with such complex dense flow systems .%针对颗粒流全尺度模拟时的干碰撞问题，在内嵌边界多重直接力全尺度算法中加入软球碰撞模型。通过空气中小球碰撞壁面和小球在粗糙表面上滚动2个典型算例，验证了软球模型在全尺度模拟中对干碰撞作用求解的适用性和准确性。对软球模型各主要参数的敏感度分析表明：时间步长越小，碰撞计算越精确；弹簧刚度系数越小，软球模型的接触特征时间越长，全尺度计算受到的资源限制越小；网格尺度、速度恢复系数对软球模型在全尺度模拟中的求解精度影响不大。实验室尺度气固鼓泡床的全尺度模拟结果表明，该方法可用于计算复杂的稠密流动体系。