Experimental Investigations on the Wave Making in the Near-Field of Ships

Abstract

The aim of this paper is to visualize the cause of the defect of wave making theories of ships through wide-ranged experiments. No effective wave making theory will be generated without precise understanding of physical phenomena. Flow field analysis and wave pattern analysis are extensively carried out with wide-beam fine ship models and a two-dimensional simple ship model. Singularities of the waves in the near-field of ships are carefully analysed and discussed, and following principal conclusions are attained. 1) Singular characteristics of wave making in the near-field of ships contribute to wave resistance in a different manner from Kelvin-Havelock's wave making theory. 2) Newman-Sharma's method cannot offer true value of wave resistance. 3) The discrepancies between C_w and C_<wp> is to be approximately measured as momentum loss behind ships, which is due to the properties of singular waves, not due to wave breaking. Wave breaking phenomena is only one of the properties of singular waves. 4) Terms including υ of the exact free surface condition take a significant part for the fulfillment of this condition.