Vertical force prediction of planing craft in calm water based on variable section slamming model

Abstract

This paper proposes a prediction method based on a variable section slamming model for the precise calculation of the vertical force of planing craft. Using the idea of 2D+t theory, the three-dimension planing craft hydrodynamic problem is transformed into a two-dimensional slamming problem. For better hydrodynamic performance in practical engineering, the transverse geometrical section of monohull planing craft is usually designed to be variable in the longitudinal direction. In the 2D+t point of view, this problem is numerically treated as a water impact problem of a section with constantly deforming shape. However, previous conventional slamming models cannot directly take the section variation effect into account. To address this deficiency, this paper develops a new Modified Logvinovich Model (MLM). By revising the body surface boundary condition, the newly proposed model can be applied to calculate the slamming force of two-dimensional variable transverse section. The vertical force distribution and the attitude of planing craft are determined by 2D+t theory and the computational fluid dynamics (CFD) method. The results of 2D+t theory considering the variable transverse section are in good agreement with the CFD results.