Robustness and quality of squat predictions in extreme shallow water conditions based on RANS-calculations

Abstract

Estimating ship squat is necessary to maintain safe navigation in the approach channel of harbors. The trim pattern of ships in shallow and restricted water can vary from trim bow down to stern down or variable trim orientation in dependence of the speed. The sinkage and trim pattern of three Postpanmax container ships in extreme shallow and confined water, with a water depth to draft ratio of less than 1.2, are predicted by using a RANSE based CFD method. The developed CFD setup is also applied for simulations of the DTC (Duisburg Test Case) container ship benchmark of the 5th International Conference on Ship Manoeuvring in Shallow and Confined Water (MASHCON). The predicted results are compared with model test data to analyze the robustness of the CFD method and to evaluate the quality of the squat predictions. The presented RANS method is robust and the quality of the predicted squat values is better than 20% deviation. When both CFD and EFD share the same model setup, the prediction deviation is less than 10%.