颗粒碰撞的直接模拟算法

为研究细微颗粒间平均碰撞率,构建了直接模拟三维空间内颗粒碰撞的数值方法.对剪切流内夹带的无惯性颗粒和自由运动颗粒的碰撞过程分别进行了数值模拟,得到的颗粒平均碰撞率的模拟值与理论值的相对误差小于1%.在碰撞颗粒对的搜索过程中,引入网络排除法等优化措施,使计算量降低两个量级以上,而不增大相对误差.采用不同的Δt模拟同一颗粒群的运动,发现较小的时间步长可以避免因为截断误差增大的相对误差.在不遗失颗粒碰撞的条件下,较密的计算网格可明显减少计算量.

Direct Numerical Simulation Method of Inter-particle Collision

A algorithm for direct numerical simulation of inter-particle collision in 3D space is built and verified by comparison with analytical solutions of collision rate of particulate flow under fine and heavy limits respectively. Optimizations such as exclusive method for computational mesh during identification of collisions can reduce the running time to 0.75% of that before optimization, without increscent relative error. It also shows that less time step can give more exact result in comparison of numerical simulations of the same particle group with different time steps. In precondition of no lost collision, fine computational mesh will save running time obviously.