Free Surface Shock Waves around Ships and Their Effects on Ship Resistance

Abstract

The authors1), 2) experimentally examined the flow field in the near-field of ships and clarified the reason of existing discrepancies between wave making resistance theories and experimental results. Non-dispersive waves exist around ships, which considerably contribute to ship resistance. Without sound clarification of these waves, trustworthy development of a ship resistance theory will not be expected.In this paper, the characteristics of non-dispersive waves around ships are further studied through experiments, and it is verified that these waves satisfy the conditions that shock waves in compressible fluid and nonlinear shallow water waves do. A kind of shock wave exists around ships, and it must be characterized by a nonlinear wave theory. The authors named these non-dispersive waves as free surface shock wave.New direction of research is pursued taking into account that Kelvin's dispersive waves and free surface shock waves coexist around ships. Some way of analysis and effects of free surface shock waves on dispersive waves are discussed.