Development of a VoF-fractional step solver for floating body motion simulation

Numerical simulation of floating or submerged body motions is presented based on a Volume of Fluid (VoF)-fractional step coupling. Solving a scalar transport equation for volume fraction of two phases results in a single continuum with a fluid property jump at the interface. In addition, velocity and pressure fields are coupled using the fractional step method. Based on integration of stresses over a body, acting forces and moments are calculated. Using the strategy of non-orthogonal body-attached mesh and calculation of motions in each time step result in time history of hydrodynamic motions. To verify the accuracy of the numerical procedure in simulation of two-phase flow, sloshing and dam breaking with obstacle problems are investigated. Besides, motions simulation strategy is evaluated by using a cylinder water entry test case. To demonstrate the capability of the simulation, barge resistance is calculated in two cases of fixed and free motion (2-DoF). All of the results are in good concordance with experimental data. The present method can be extended for full nonlinear motion of ships in waves.