A novel volume of fluid ghost-cell immersed boundary method for free surface flow interacting with structures

This paper presents a novel volume of fluid ghost-cell immersed boundary (IB) method for two-phase free surface flow interacting with structures. To circumvent the disturbance occurring around the intersection area of the IB and free surface when using the interpolation method for variable reconstruction, the fluid-structure interaction is firstly considered with the orthogonal IB by mimicking the imposition of boundary conditions in the body-conformal grid method. Treatments are subsequently performed to account for the non-orthogonal effect in accurately simulating the FSI, including the newly proposed flux-scaling and IB velocity re-evaluation methods. Further, a variable smoothing process and a flux correction method are adapted to handle moving boundary cases. Based on OpenFOAM, a two-phase flow solver has been developed. Both stationary and moving immersed boundary cases are used for validations. The numerical results reasonably agree with the corresponding laboratory data and other numerical simulation results, demonstrating the disturbance being effectively depressed and the solver's accuracy in capturing fluid-structure interactions involving free surface flow.