Nonlinear dynamic pressure evaluation along progressive wave profiles

Abstract

An experimental and a computational technique is introduced for the solution of the dynamic pressure evaluation problem in progressive waves, at the locations close to the free surface. The experimental technique developed, utilizing measurement ports in motion together with the waves generated by a wavedozer, at the same speed and direction, eliminates the effect of wave splashing at the measurement ports and allows pressure measurements at any vertical cross section of the wave profile at the locations close to th^e free surface. The wavedozer problem has been modeled as an initial-boundary value problem of a triangular pressure field moving at a constant horizontal speed on the undisturbed free surface of a towing tank, generating a train of waves behind it. The fluid is considered inviscid, incompressible and irrotational. Exact nonlinear free surface boundary conditions are applied at the real free surface. The Boundary Element Method(BEM), a recently developed numerical procedure, is used as the numerical. solution method for this nonlinear initial-boundary value problem. The variation of dynamic pressures with depth at selected vertical cross sections of progressive waves is determined. The results of the experimental measurements and nonlinear BEM solutions are compared to each other and to first and second order Stokes theory results.