Current Affairs: Model Tests, Semi-Empirical Predictions and CFD Computations for Current Coefficients of Semi-Submersibles

Current loads on stationary vessels have been investigated as part of the Current Affairs Joint Industry Project (JIP). Model-tests, semi-empirical models and CFD methods were used to predict these loads. This paper examines one configuration out of the eight tested in the JIP; an idealized semi-submersible consisting of two square rounded-corner columns connected with a pontoon. The model experiments, empirical model predictions and CFD results are presented and discussed. ‘Blind’ and ‘Improved’ CFD computations (with and without knowledge of the experimental results) have been carried out by the JIP participants. Comparisons between these results are made, deviations from the experimental data are quantified and conclusions are drawn. Two key issues for modeling accuracy are identified and discussed; the location of the transition to turbulent flow and the control of the numerical errors.