Nie Pin, Chattoraj Joyjit, Piscitelli Antonio, Doyle Patrick, Ni Ran, Ciamarra Massimo Pica
School of Physical and Mathematical Science, Nanyang Technological University, Singapore 637371, Singapore.
Singapore-MIT Alliance for Research and Technology, Singapore 138602, Singapore.
Phys Rev E. 2020 Sep;102(3-1):032612. doi: 10.1103/PhysRevE.102.032612.
Frictional forces affect the rheology of hard-sphere colloids, at high shear rate. Here we demonstrate, via numerical simulations, that they also affect the dynamics of active Brownian particles and their motility-induced phase separation. Frictional forces increase the angular diffusivity of the particles, in the dilute phase, and prevent colliding particles from resolving their collision by sliding one past to the other. This leads to qualitatively changes of motility-induced phase diagram in the volume-fraction motility plane. While frictionless systems become unstable towards phase separation as the motility increases only if their volume fraction overcomes a threshold, frictional systems become unstable regardless of their volume fraction. These results suggest the possibility of controlling the motility-induced phase diagram by tuning the roughness of the particles.
在高剪切速率下，摩擦力会影响硬球胶体的流变学。在此，我们通过数值模拟证明，摩擦力还会影响活性布朗粒子的动力学及其由运动性诱导的相分离。在稀相中，摩擦力会增加粒子的角扩散率，并阻止相互碰撞的粒子通过彼此滑过的方式来解决碰撞问题。这导致了在体积分数 - 运动性平面中运动性诱导相图的定性变化。对于无摩擦系统，只有当它们的体积分数超过阈值时，随着运动性增加，系统才会对相分离变得不稳定；而对于有摩擦系统，无论其体积分数如何，都会变得不稳定。这些结果表明，通过调节粒子的粗糙度来控制运动性诱导相图是有可能的。
