INVESTIGATION OF NUMERICAL SCHEMES IN AIR CAVITY COMPUTATIONS

Paper i proceeding, 2016

Air cavity and air chamber concepts have been proven to be an efficient way for drag reduction in low-speed ships. Series of experiments were conducted in the SSPA cavitation tunnel to simulate the working conditions of an air filled cavity under the hull of a ship. In this paper, study is extended with a numerical validation using a CFD Open Source solver, OpenFOAM (OF). Volume of fluid (VOF) approach, which uses phase volume fraction (alpha) is used to compute the incompressible two-phase viscous flow. The influence of different numerical methodologies on the advection of "alpha" is studied. Different schemes from diffusive first-order to higher order TVD (Total Variation Dimensioning) schemes like SUPERBEE are tested. Results are also drawn from counter-gradient convective flux implementation in OF VOF approach. Conclusions are drawn from the wave profile, wave sloshing pressure force and viscous force. It was observed that, as more compressive interface capturing methods were used, the aft force was better predicted but distorts the wave profile and under predicts the beach plate force.