Motion of a sphere and the suspending low-Reynolds-number fluid confined in a cubic cavity

Dynamics of a spherical particle and the suspending low-Reynolds-number fluid confined by a cubic cavity were studied numerically. We calculated the particle's hydrodynamic mobilities along x-, y-, and zdirections at various locations in the cavity. The mobility is largest in the cavity center and decays as the particle becomes closer to no-slip walls. It was found that mobilities in the entire cubic cavity can be determined by a minimal set in a unit tetrahedron therein. Fluid vortices in the cavity induced by the particle motion were observed and analyzed. We also found that the particle can exhibit a drift motion perpendicular to the external force. Magnitude of the drift velocity normalized by the velocity along the direction of the external force depends on particle location and particle-to-cavity sizes ratio. This work forms the basis to understand more complex dynamics in microfluidic applications such as intracellular transport and encapsulation technologies. (c) 2022 The Author(s). Published by Elsevier Ltd on behalf of The Chinese Society of Theoretical and Applied Mechanics. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)