Numerical strategies to speed up CFD computations with free surface-Application to the dynamic equilibrium of hulls

This article presents two numerical procedures to speed up computations when dealing with a Reynolds Averaged Navier Stokes (RANS) solver based on the Volume of Fluid (VoF) or multifluid method to treat the free surface. The first one is a time-splitting procedure for the volume fraction equation, enabling the use of larger time steps for the resolution of the flow, without penalizing accuracy. However, these large time steps destabilize the coupling with the ship motion simulation when computing a dynamic equilibrium position in marine applications. The second procedure is therefore a quasi-static approach to solve the coupled problem of dynamic equilibrium. A comparison of these procedures with classical simulations shows that numerical solutions of realistic problems can be obtained up to four times faster.