An experimental and numerical study on solitary wave loads at cylinders near the bed

Abstract

The present study describes an experimental and numerical investigation on the horizontal and vertical hydrodynamic forces given by solitary waves on horizontal circular cylinders placed near a rigid horizontal bed. The experimental campaign was conducted in the wave channel of the University of Calabria in which twelve pressure sensors were installed along the external surface of a cylinder located at gap-to-diameter ratios equal to 0.25 and 0.1. The numerical modeling was carried out using the open source OlaFlow model, based on the OpenFOAM solver, in order to simulate the wave forces, also extending the range of experiments. The resulting force field was defined by the dominance of the horizontal inertia force along the flow direction and by the lift force along the transversal one. The values of the hydrodynamic forces and the free stream kinematics were adopted to calibrate the hydrodynamic coefficients (drag, lift and horizontal and vertical inertia) involved in the Morison formula and in a proposed version of the transverse equation through the use of the weighted least square approach. For practical aims, semi-analytical relationships to determine the hydrodynamic coefficients as a function of wave amplitude and water depth are presented.