Hydrodynamic interaction between a pair of swimmers in power-law fluid

摘要

Hydrodynamic interaction between swimmers in power-law fluid is systematically investigated by using an immersed boundary-lattice Boltzmann method. The squirmer model is applied to mimic swimmers and distinct kinematic features are found for them in different types of power-law fluids. For parallel interactions, pushers (a type of swimmers) attract each other to certain orientation angles eventually while pullers (another type of swimmers) push themselves away and turn to the head-to-head state. For interactions with initial swimming towards each other, puller eventually departs away from the other one while pusher is more easily locked at certain location. The feature of power-law fluid is responsible for the trajectories of locomotion. In addition, the distribution of viscosity around the swimmer deeply relies on the tangential velocity at the boundary. The peaks and valleys of the viscosity locate at sites where the streamlines are parallel and normal to the surface of the swimmer, respectively. Finally, the collision time for neutral swimmer (β=0) and a kind of puller (β=2.5) decreases as power-law index increases while a non-monotonic relation is found for another kind of puller (β=5).