Simulation Method of Microscale Fluid-Structure Interactions: Diffuse-Resistance-Domain Approach

Direct numerical simulations (DNS) of microscale fluid-structure interactions (mFSI) in multicomponent multiphase flows pose many challenges, including the thermodynamic consistency of multiphysics couplings, tracking of moving interfaces, dynamics of moving triple-phase contact lines, and the coupling of multiphase hydrodynamics with phase transition dynamics. We propose and validate a generic DNS approach: Diffuse-Resistance-Domain (DRD) approach. It overcomes the above challenges by employing Onsager's variational principle (OVP) to formulate dynamic models and combining traditional diffuse-interface models for fluid-fluid interfacial dynamics with a novel implementation of complex fluid-solid interfacial conditions via smooth interpolations of dynamic-resistance coefficients across interfaces. After careful validation by numerous benchmark simulations, we simulated several cutting-edge, challenging mFSI problems across diverse fields. This generic DNS approach offers a promising tool for elucidating physical mechanisms, manipulating microscale fluid dynamics, and optimizing engineering processes across diverse fields.