Observation of wake flow on a tanker model with drift angle.

For a full tanker ship model running with a constant drift angle, oil film method and dye tracer method of flow visualization technique were applied to the observation of separation vortices, streamlines near the ship hull and limiting streamlines on the hull surface. Comparing these results with measured pressure distribution on the hull and vorticity distribution in the wake flow, a lot of information about the flow field obtained by tank experiment was confirmed to have consistence each other. For example, position of 3-D separation lines and directions of surface streamlines correspond well to the peak and gradient of pressure distribution respectively. It is shown that flow visualezation techniques are quite useful to investigate not only the flow field structure but also the ship motion, because separation of flow, initiation and behavior of vortices are keys to understand the wake flow and hydrodynamic force acting on the ship in maneuvering motion.