Application of a combined IB–VOF model to wave–structure interactions

A combined immersed boundary (IB) and volume of fluid (VOF) methodology is used to simulate the interactions of free surface waves and a submerged solid object, either stationary or in motion. The IB method is proved to be capable of dealing with a moving solid boundary by the simulation of a square cylinder oscillating in a fluid at rest. The combined IB–VOF model is further validated by simulating a solitary wave traveling over a shelf, and the numerical results depicting the free surface evolutions are well compared with experimental and numerical results presented by other researchers. Finally, the IB–VOF model is applied to two engineering cases. One is to study progressive periodic waves propagating over a fixed circular cylinder close to the bed. The boundary layer separation is carefully examined and the vortices shedding mode in each wave period is observed. The other case is to investigate the wave generation caused by a bed in complex oscillating motion. The simulated wave evolution at three stations compares favorably with the experiment in terms of the shape, arriving time and soliton number. The leading soliton propagating speed is found to be well approximated by gh, which can be used to estimate the arriving time of the leading wave in tsunami prediction.