The relative significance of
the parallel middle body and stern form in the wake formation of single-screw
large ships and their contribution to the ship?s viscous resistance are studied by using computational fluid dynamics (CFD). A
10450-DWT tanker is considered by varying the ratio of the
parallel-middle-body?s length to the ship?s length (Lmb/L) and by varying the shape of the stern form from a
V-like to a U-like underwater stern transom section. In all the calculations,
the principal dimension and the displacement of the ships are kept constant. A
larger value for the parallel-middle-body relative length (Lmb/L) of ships with the same stern form results in a
larger drag coefficient but does not affect the nominal wake fraction
significantly. A change in the shape of the underwater stern form,
from a V-like to a U-like section, results in a much larger drag coefficient
ascribed to the much larger wake fraction. The stern form dominantly affects
the nominal wake fraction and the ship?s viscous resistance compared to the
parallel-middle-body relative length.
