A new free surface flow RANSE solver has been developed based on the OpenFOAM framework. The solver addresses some of the main deficiencies of OpenFOAM’s standard free surface solver. It uses advanced higher order discretization schemes for the volume of fluid variable, a reconstruction of the pressure at the free surface for proper treatment of the jump of the pressure gradient at the free surface and a special method for the generation and damping of sea waves and ship generated waves at inlet and outlet of the flow domain. This new solver is used for the simulation of advanced flow problems for sailing yachts and small boats: resistance investigations at very high Froude number, investigation of the behaviour of sailing yachts in head waves and the surfing behaviour of a sailing yacht in following waves. The paper outlines the new solver and presents some case studies demonstrating its abilities.

This paper describes some CFD and VPP investigations around a 90' yacht designed under the recently proposed class rules of an AC90 yacht to be used in a future Americas Cup. While it currently is not foreseeable if AC90-yachts will ever be sailed in the Americas Cup, these yachts provide some challenges for the designer as well as the flow analyst. In this paper, flow simulations around the fully appended hull at expected very high Froude numbers are shown as well as spinnaker flow simulations taking into account the extraordinary spinnaker design constraints. In addition, the treatment of skiff-like performance of the yacht in a VPP is investigated.

The paper reports about CFD investigations of mast and appendages of IACC Yachts, carried out for the illbruck Challenge (iC). Appendage development and optimisation is based on a mixture of potential flow and RANSE simulations taking into account bulb, blade, wings, rudder and canoe body, neglecting the free surface. A large amount of different appendages configurations are compared.. Different grid topologies and operational conditions are investigated.. Special attention is paid to proper integration of results into VPPs. Additional RANSE calculations did take into account the free surface using two-phase-flow method. While restricted in number of test cases, these simulations provide information about inflow conditions to be assumed to the test cases where the free surface has been neglected. A second field of intensive RANSE investigations has been mast profile optimisation. While initially restricted to mast-mainsail-profiles reliable results could only be achieved if jib and even head foil are taken into account. Full three dimensional RANSE calculations have been used to prove validity of optima for mast profile geometry derived from 2DRANSE simulation results. A family of profiles is compared under various operational parameters.