Nonlinear interactions between solitary waves and structures in a steady current

Abstract

Interactions between solitary waves and structures in a steady current are studied based on a fully nonlinear wave potential theory, and a higher order finite element method (FEM) with a mesh of 8-node quadrilateral isoperimetric elements is employed to simulate the interaction in two-dimensions. Numerical examples are given by solitary waves propagating over an underwater rectangular cylinder in a steady current in a tank and solitary waves acting on single- and twin-rectangular cylinders in a steady current on free surface. Waves and hydrodynamic forces are obtained at different current speeds. It is found that the peak of diffracted wave due to the first and second reflections by an underwater cylinder clearly increase in following current. Furthermore, a packet of periodic waves with constant peak and trough are found to appear when the absolute value of the Froude number becomes large enough in single- and twin-cylinder cases. For the twin-cylinder cases, the maximum wave and horizontal force are clearly affected by the current especially in larger incident wave amplitudes and smaller spacings. In addition, the nonlinearity of wave or force becomes stronger at larger Froude numbers and larger incident wave amplitudes.