An overset grid scheme for studying particles confined to fluid interfaces

The dynamics of a particle confined to a fluid interface are strongly connected to the motion and geometry of the interface itself. In this work, a numerical framework is presented to study this connection for the case of a particle straddling a fluid interface at low Reynolds number flows. The approach utilizes a chimera (also called overset) grid in which a local body-fitted mesh attached to the particle is coupled to a fixed, global Cartesian grid covering the entire computational domain. Solutions to the governing equations are computed on each mesh independently and are then coupled via interpolation. Motion of the fluid interface is captured by the level set method and the effect of surface tension is modeled as a volumetric forcing term. The efficacy of the method is demonstrated in a series of two-dimensional simulations with an assumed constant three-phase contact angle. In particular, the effect of interfacial deformations on the drag force and torque for a particle translating between parallel plates is investigated.