Comparative Experimental and Numerical Evaluation of the Flow Field at the Stern of a Hull Form

The basic aim of this research was to compare the experimentally evaluated flow field at the stern region of a hull form with large block coefficient with the respective numerical results. To this end, a Five-Hole Pitot tube was used to capture the wake flow at the stern region of a scaled model of a bulk carrier in the towing tank of the Laboratory for Ship and Marine Hydrodynamic (LSMH) of the National Technical University of Athens (NTUA). The measurements were carried out at three aft sections of the model, where large scale vortices are usually generated: the section at the propeller, a section ahead of it and another one under the transom stern. The model was towed at a speed of 1.214 m/s, corresponding to Fn =0.17. The tube was calibrated on air at an equivalent Re, while a second in-house calibration technique was developed to consider installation misalignments and to increase overall measurement accuracy. The numerical calculation of the flow was performed using CFD tools developed at LSMH of NTUA. The method solves the RANS equations by applying the finite volume approach underneath a prescribed free surface which is derived by a potential flow code. The numerical results are in good agreement with the experimental ones, confirming the robustness of both methods.