Hemauer J, Qiu M, Feng J J, Loudet J-C
Department of Mechanical Engineering, Technical University of Munich, 85748, Garching, Germany.
Department of Mathematics, University of British Columbia, Vancouver, BC, V6T 1Z2, Canada.
Eur Phys J E Soft Matter. 2021 Mar 15;44(3):30. doi: 10.1140/epje/s10189-021-00025-w.
We use dynamic numerical simulations to investigate the role of particle rotation in pairwise capillary interactions of particles trapped at a fluid interface. The fluid interface is modeled with a phase-field method which is coupled to the Navier-Stokes equations to solve for the flow dynamics. Numerical solutions are found using a finite element scheme in a bounded two-dimensional geometry. The interfacial deformations are caused by the buoyant weight of the particles, which are allowed to both translate and rotate due to the capillary and viscous forces and torques at play. The results show that the capillary attraction is faster between freely rotating particles than if particle rotation is inhibited, and the higher the viscosity mismatch, the greater the effect. To explain this result, we analyze the drag force exerted on the particles and find that the translational drag force on a rotating particle is always less than its non-rotating counterpart due to attenuated velocity gradients in the vicinity of the particle. We also find that the influence of interfacial deformations on particle rotation is minute.
我们使用动态数值模拟来研究颗粒旋转在捕获于流体界面的颗粒间成对毛细管相互作用中的作用。流体界面采用相场方法建模，该方法与纳维-斯托克斯方程耦合以求解流动动力学。在有界二维几何结构中使用有限元格式找到数值解。界面变形由颗粒的浮力引起，由于毛细管力和粘性力及扭矩的作用，颗粒既可以平移也可以旋转。结果表明，自由旋转颗粒之间的毛细管吸引力比颗粒旋转受到抑制时更快，并且粘度失配越高，效果越明显。为了解释这一结果，我们分析了施加在颗粒上的阻力，发现由于颗粒附近速度梯度的衰减，旋转颗粒上的平移阻力总是小于其非旋转对应物。我们还发现界面变形对颗粒旋转的影响很小。
