【摘要】 采用无网格伽辽金法对多相流动中的颗粒运动进行了直接数值模拟.颗粒的受力通过积分颗粒表面压力和黏性力获得,颗粒运动用牛顿运动定律表示.在模拟两个颗粒一前一后的下落过程中,两颗粒呈现出文献中所观察到的拖曳、亲和、翻滚的现象.在处理颗粒碰撞上,无网格法显示了其优越性,实现了颗粒真正碰撞,解决了困扰多相流直接数值模拟发展的一个重要问题.最后,还模拟了6个颗粒在管道内的下落过程.这些计算都表明,由于无网格法不需要单元的连接,适合于推广到大型的气固两相流的直接数值模拟计算中,从而为多相流直接数值模拟的广泛开展奠定坚实的基础.更多还原

【Abstract】 The element free Galerkin method (EFG) was used in the direct numerical simulation of multi-phase flows.Forces acting on particles were calculated by integrating the pressure and shear forces over particle surfaces.In the simulation of one particle’s falling process,it was found that a Karman vortex street was formed behind the particle with the increase of the particles’velocity and two particles’ falling process was simulated as well.The known drafting, kissing and tumbling phenomenon which was in agreement with experimental results was reproduced.In the simulation, EFG showed its advantage in dealing with particle’s collisions.The collision of a moving particle and a stationary cylinder was simulated and EFG was capable of dealing with real-contact collisions, while other methods based on meshes failed.Moreover, six particles’ falling process was calculated in this study.All these simulations showed that EFG could be applied to the large-scale direct numerical simulation of multiphase flows.更多还原