A Study on Flow Around a Immersed Transom Stern

Abstract

In the case of a ship with wide beam and shallow draft, it is considered that a immersed transom stern has the advantage of a cruiser stern for ship resistance and stern structure. In this paper, making a ship with the ratio of beam to length B/L of about 0.15 and the ratio of draft to length d/L of about 0.03 the object of study, flow around her immersed transom stern was studied. The results are summarized as follows. 1. Flow around a stern of a high speed ship such as the flow separates at the lower edge of transom can approximate by the irrotational flow due to the pressure distribution on free surface which satisfies the linear water surface condition. For a ship of which B/L is nearly equal 0.15, the bottom pressure and the stern wave are expressed approximately by equation (19) and (18) respectively. For a ship of which B/L is smaller than 0.15, the stern flow is expressed approximately by equation (13) and the limit of application of it with B/L differs by the stern form. 2. Flow just after transom of a low speed ship is turbulent. For the estimation of pressure in the turbulent region, equation (30) may be available for the actual problem. The irrotational flow outside the turbulent region may analyse approximately by using the above mentioned equations for a high speed ship and flow analysis of a ship of which B/L is about 0.15 and smaller than it is not so difficult.