CFD-BASED SIMULATION OF THE FLOW AROUND A SHIP IN OBLIQUE MOTION AT LOW SPEED

Abstract

Ships tend to maneuver in oblique motion at low speed in situations such as turning in a harbor, or during offloading, dynamic positioning and mooring processes. The maneuverability criteria proposed by IMO are valid for ships sailing with relatively high speeds and small drift angles, which are inadequate to predict ship maneuverability in low speed condition. Hydrodynamic performance of ships maneuvering at low speed is needed to know for safety issues. A CFD-based method is employed to predict the flow around an Esso Osaka bare hull model in oblique motion at low speed, where the drift angle varies from 0° to 180°. The URANS method with the SST k-ω model is used for simulating ship flows with drift angles 0°~30° and 150°~180°, and DES method for simulating ship flows with drift angles 40°~150°. Verification and validation studies are conducted for drift angles of 0° and 70°. The vortex structures at typical drift angles of 0°, 30°, 50°, 70°, 90° and 180° are analyzed. The effects of drift angle and ship speed are demonstrated.