Forces and Moments Acting on a Submersible Moving Beneath the Free Surface or Near a Wall

摘要

The forces and moments acting on a submersible are computed when it is beneath the free surface or near a wall. The method used in this report is based on potential theory. In the computation of forces and moments on the hull, a three-dimensional method is applied. The free surface condition is linearized and the body boundary condition is exact. The body surface is discretized with surface elements and the singularity of source and sink is distributed on them. The strengths of the unknown sources and sinks are determined through the body boundary condition. A two-dimensional method is applied to compute forces and moments of the hydrodynamic control surfaces. The boundary conditions are the same as those for three-dimensional case. Computed forces and moments of the control planes are added to those of the bare hull. To include the interference effect of the hull on the planes, the flow velocity at each control plane is computed with existence of the hull. There are some discrepancies between computed results and experimental data because of the effect of viscosity. The overall trends in the computed results are same as those of the experiments.