A surface flux correction-based immersed boundary-multiphase lattice Boltzmann flux solver applied to multiphase fluids–structure interaction

The interaction between multiphase fluids and structure in engineering is ubiquitous, in which the capture of the contact line between the multiphase fluids and the moving structure is challenging for numerical simulation. In this work, a surface flux correction-based immersed boundary-multiphase lattice Boltzmann flux solver (IB-MLBFS) is developed and applied to investigate the multiphase fluids–structure interaction. In addition to applying the velocity correction by the immersed boundary method (IBM) that has been widely applied in fluid–structure interaction (FSI) of single-phase flow, the surface flux correction is appended by IBM as well on the contact line between the multiphase fluids and the moving structure so that both the Dirichlet boundary condition and the Neumann boundary condition on the contact line are satisfied, which ensures the successful simulation of multiphase fluids–structure interaction. For the numerical study, the simulation of water entry of a half-buoyant cylinder is carried out first as the validation of the IB-MLBFS by comparing with results of both experiments and smoothed particle hydrodynamics (SPH). After that, the phenomena of interface entry and exit of a sphere with different densities from different initial positions are simulated to show the reliability of IB-MLBFS in complicated interface interaction. The instantaneous contours of fluids density and solid boundary are shown to illustrate the interface and the structure, and the hydrodynamic parameters such as the force and the displacement are given. The results conclude that the IB-MLBFS is reliable and has sufficient accuracy so that it can represent the details of the flow field and the dynamic response of the structure. For example, the phenomenon of the separated and the butted fluids surrounding the structure in this simulation has been clearly revealed, which indicates its wide application for multiphase fluids–structure interaction problems in engineering.