Forces on a fixed barge due to Stokes 5th-Order laboratory waves

Abstract

This paper presents the results of experiment of nonlinear Stokes 5th order waves and forces measured in the Ocean Engineering Hydrodynamic Laboratory. It also presents analysis of the data and the comparison with hydrodynamic theory. We investigated the reason for overestimation of forces with potential theory by using the data obtainable by PIV measurement. Due to the lack of experience, we failed to visualize the particle motions simultaneously near the hull with the wave and force measurements. Thus we had to propose a simple mathematical model relating the particle velocity field, the instantaneous position of a progressing wave and the location of a barge that produces the maximum horizontal forces. The particle velocity field is qualitatively related to the formation of visible vortices when the wave forces become maximum. It was concluded that the reduction of the forces from the potential theory was due to the vortex shedding due to the viscous flow near the hull.