Microscopic investigation of Rayleigh-Taylor instability in a sedimenting suspension

我们通过微观颗粒和流体力学的数值计算来研究沉积悬浮液中的瑞利-泰勒不稳定性。由于晶格玻尔兹曼方法与浸入边界法相结合的快速和大规模并行机器的可用性，GPU加速了基于粒子的中尺度流体动力学模拟。当采用浸入式边界格玻尔兹曼方法时，我们观察到固液界面上的边界滑移会导致悬架系统的计算出现较大误差。为了解决速度滑移问题，我们将两个松弛时间碰撞算子应用到晶格玻尔兹曼方法中，并证明了基于两个松弛时间的隐式修正方法的数值方法成功地防止了流动穿过固体表面和非物理速度滑移。

We investigate Rayleigh-Taylor instability in a sedimenting suspension by the numerical calculation of the microscopic particle and fluid dynamics. Because of the availability of very fast and massively parallel machines of the lattice Boltzmann method combined with the immersed boundary method, the GPU accelerates particle-based mesoscale hydrodynamic simulations. When we use the immersed boundary-lattice Boltzmann method, we observe the boundary slips on the solid-liquid interface that cause the significant error in the computation of the suspension system. In order to solve the velocity slip problem, we apply two relaxation times collision operator to the lattice Boltzmann method, and demonstrate that our numerical method based on the implicit correction method with the two relaxation times succeeds in preventing the flow penetration through the solid surface as well as unphysical velocity slips.