URANS And DES for Delft catamaran for static drift conditions in deep water

Understanding of three-dimensional separation around ships on straight course or under maneuvering is important for developing next generation ships with improved performance in extreme maneuvers. The separation causes vortex-dominated flows in which the vortex breakdowns at sufficiently high drift angles. The object of this study is to identify and analyze the vortical structures and instabilities around high-speed Delft catamaran and validate URANS and DES solver CFDShip-IowaV4 in collaboration with NATO AVT 183 (Reliable Prediction of Separated Flow Onset and Progression for Air and Sea Vehicles). The computations are performed at wide ranges of Froude numbers (Fr) and drift angels (B). The CFD results are compared to EFD data provided from different facilities including BSHC, INSEAN and Delft. The data included motions, integral variables, wave profile and SPIV measurements. Three sets of CFD simulations are performed: (1) hull free to heave and pitch with 0.3

Hydrodynamic forces, moments and motions for B=0 are compared to the experimental results from different facilities. In general, good agreement between experiments conducted at the Delft and INSEAN facilities, and CFD are achieved at B=0 with forces and motions errors less than 13%D. Although there is a good agreement on the force between CFD and BSHC experiments, the motions show large error with more than 30%D for heave and pitch. The difference in the experimental results could be attributed to the difference in non-dimensional depth in the experiment. For 0