中尺度流体动力学模拟中angular momentum守恒的相关性
Relevance of angular momentum conservation in mesoscale hydrodynamics simulations
摘要：
角动量在流体中是守恒的，只有少数例外，如铁磁流体。然而，它可以在流体模拟中局部违反，以减少计算成本。使用基于粒子的模拟方法，多粒子碰撞动力学，它可以打开或关闭角动量守恒的影响，这种违反进行了研究。为此，我们研究圆形Couette流之间的同心和偏心的圆柱体，非物理扭矩由于缺乏角动量守恒被发现，而速度场不受影响。此外，在模拟接触时具有不同粘度的流体和溶剂中的星形聚合物时，会出现不正确的角速度。这些结果与基于宏观应力张量的理论预测在定量上一致。
英文摘要：
The angular momentum is conserved in fluids with a few exceptions such as ferrofluids. However it can be violated locally in fluid simulations to reduce computational costs. The effects of this violation are investigated using a particle-based simulation method, multi-particle collision dynamics, which can switch on or off angular-momentum conservation. To this end, we study circular Couette flows between concentric and eccentric cylinders, where non-physical torques due to the lack of the angular-momentum conservation are found whereas the velocity field is not affected. In addition, in simulations of fluids with different viscosities in contact and star polymers in solvent, incorrect angular velocities occur. These results quantitatively agree with the theoretical predictions based on the macroscopic stress tensor.
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