Measurements of stern flow field of a ship in oblique towing motion

Information about a flow field around a ship is necessary to develop an estimation method of hydrodynamic forces acting on a ship in manoeuvring motion. Stern flow fields of three VLCC model ships in oblique towing motion and hydrodynamic forces acting on these model ships were measured. These model ships have almost same principal dimensions but different stern shapes. There is no big difference qualitatively between stern flow fields of these model ships, characteristics of which are represented by two groups of separation vortices and their associated wakes. However, there are clear differences in strength, concentration and range of distribution of vorticity and wake. Concerning to hydrodynamic forces, difference is small among these model ships in magnitude itself of sway force and yaw moment, but there is clear difference in position of center of sway force that has a serious effect on a ship manoeuvrability.