Research on the Near-Wall Dynamics of Ellipsoidal Microrobots Based on COMSOL

Microrobots are self-propelled devices operating at the micrometer to sub-millimeter scale. At low Reynolds numbers, the near-wall locomotion behavior of these microrobots dictates the operational precision in fields such as targeted medical drug delivery. This study establishes a fluid-structure interaction (FSI) multiphysics model based on COMSOL Multiphysics, employing the squirmer in incompressible Stokes flow as the kinetic model. The research focuses on investigating the impact of different initial orientation angles on the trajectories and orientation of ellipsoidal squirmers under the conditions of a large propulsion parameter β = 9 and an initial center-of-mass height h0 = 3req. The findings indicate that significant nonlinear characteristics emerge under the strong propulsion condition of β = 9. Furthermore, the study identifies a critical initial orientation angle of −85π/512 for an ellipsoidal squirmer with an aspect ratio ar = 2 to transition from near-wall oscillation to escape. This discovery reveals the motion mode transition mechanism for strong-propulsion robots, providing a control reference for their autonomous behavior in microscale fluidic environments.