On Viscous Forces Acting Upon Moving Semisubmersible.

Abstract

The paper deals with the viscous effect on the hydrodynamic forces acting on a semisubmersible. To predict the forces by the Hooft's method, the values of drag, added mass and lift coefficients for each element of it are needed. They are obtained at low K_c number by the forced oscillation test for two-dimensional cylinders with the same cross sections as the lowerhull and the column. The drag and lift coefficients are found to be significantly dependent on the angle of attack. The predicted results for hydrodynamic forces acting on a rolling and swaying submersible using the measured hydrodynamic coefficients are in fairly good agreement with the experimental ones.