IMPROVED TIME DOMAIN SIMULATION OF PLANING HULLS IN WAVES BY CORRECTION OF THE NEAR-TRANSOM LIFT

Article type: Research Article

Authors: Garme, Karl

Affiliations: Royal Institute of Technology KTH, Department of Aeronautical and Vehicle Engineering, Stockholm, Sweden

Abstract: Time-domain simulation, based on 2-dimensional high-frequency added mass formulation of the sectional forces, is a computationally attractive approach to the non-linear behaviour of the planing craft in waves. Nevertheless, the 2-dimensional strip approach, demands for corrections of the lift distribution in order to correctly model the running attitude which is significant for the loads and motions for planing craft in waves. This has traditionally been made by a reduction of the hydrostatic lift and moment with reference to the geometrical fact that the transom stern is dry. This action improves the simulation of the running attitude in calm water but not necessarily of the dynamic behaviour in waves. The paper proposes a correction operating on both the hydrostatic and the hydrodynamic terms of the load distribution. A reduction function is chosen on the basis of model test measurements of the near-transom pressure, and on published model data on running attitude. The approach is satisfactory validated in calm water, regular and irregular waves. Simulations of model experiments and comparison with measurement time series are presented. The correction improves the simulation in both calm water and in waves for a wider speed range compared to a correction limited to the hydrostatic terms.

Journal: International Shipbuilding Progress, vol. 52, no. 3, pp. 201-230, 2005