Effects of Parallel-Middle-Body Relative Length and Stern Form on the Wake Fraction and Ship Resistance

Abstract

Effects of parallel-middle-body relative length and stern form of a 10450-DWT tanker on the wake fraction and ship resistance are studied by using computational fluid dynamics (CFD). Calculations were done with varying ratios of parallel-middle-body length to ship length (Lmb/L) and with varying stern forms. The same ship displacement is maintained in all the calculations. It is found that a larger value of Lmb/L for ships with the same stern form results in a larger ship resistance but does not affect the wake fraction significantly. A more abrupt stern form results in a larger wake fraction and in a much larger ship resistance. In the former case, the increase of ship resistance is ascribed to the increase of the wetted surface area (WSA) of the ship and in the latter case particularly to the much larger wake fraction.