Numerical Simulation Method for Flows About a Semi-Planing Boat with a Transom Stern

A new simulation method based on computational fluid dynamics (CFD) is developed for a semiplaning boat with a transom stern in unsteady motion. The time-dependent Reynolds-averaged Navier-Stokes (RANS) equation is discretized by the finite-volume method and solved by the MAC-type solution algorithm, The free-surface treatment in this study is based on the density function method. The motion of the boat is simultaneously solved by combining the equation of the motion of the boat with the flow computation, and the effect of the boat motion is implemented by the moving grid method in the flow computation. Simulations for two types of practical high-speed boats are performed in the Froude number range from 0.5 to 1.0 and the results are compared with experimental ones. It is demonstrated that this method can simulate both the flow about the boat and the running attitude in free-to-run condition with a sufficient degree of accuracy and that it can be used as an effective tool for the development of hull form of practical high-speed boats.