Numerical Analysis of Free Surface Flow around Sailing Yacht by Means of Panel Method : 1st Report:Calculation of Hydrodynamic Forces in Upright Condition without and with Leeway

Abstract

In the previous study by one of the authors et al., hydrodynamic forces acting on sail boats are calculated by means of PAFS (Panel method Applied to Free Surface flow). In those results, however, some problems are found; for example, ware resistance coefficients estimated by PAFS become negative in the low speed range. In the present study, in order to improve the results, singular characteristics are investigated about the analytical formulae of influence coefficients given by Morino, because it can be considered that the problems of the previous results are raised by these singularities. According to this investigation, a modified scheme of PAFS is suggested. First of all, numerical examples of the free surface flow around KIT-34, a sail boat designed by Masuyama, are given under the condition without leeway. Based on the numerical examples, validations of the present modification are studied. As the next step, hydrodynamic forces acting on sail boat KIT-34 with leeway are estimated, since predictions of hydrodynamic characteristics of a sail boat with leeway are indispensable to the hull form design.