Unsteady Reynolds-averaged Navier-Stokes simulations are carried outfor the merchant ship with three different rudders (fishtail-sectionedrudder with end plates, fishtail-section rudder without end plates, andnormal rudder) under turning circle maneuver. The present computationsare able to capture the trends in trajectory due to the difference of rudderangle and the geometry of the rudder compared to the reference sea trialdata. Three features are identified for the high lift rudder (fishtailsectionedrudder with end plates) in turning circle maneuver of the targetship. First, it notably decelerates the longitudinal velocity of the ship atthe beginning of turning motion. Second, it has the largest rudder normalforce coefficient compared to the other rudders over whole turningmotion which is mainly due to the increase of positive pressure regionon the pressure side of the rudder bounded by the end plates. Third, theend plates reduce 1st dominant frequency and amplitude of rudder normalforce coefficient compared to fishtail-section rudder without end platesamong steady turning phase although the differences in ship motion andpropeller rotation speed may also be affect to this phenomenon.
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