OpenFOAM Simulation of Bores and Surges on Coastal Structures

The hydrodynamic forces on coastal structures impacted by tsunami depend on the wave Froude number, the sizes, and shapes of the structures and also on whether the structures stand in water or on dry land at the time of the impact. We conducted simulations using full Navier-Stokes equations to determine the wave impact on a vertical wall -- i.e., a structure of infinite width -- and a structure of finite width. In the case of steep waves on a wet bed, the wave-drag coefficient rose to a peak on impact and then settled to a wave-structure interaction equilibrium. In the case of smooth waves on dry land, the approach to the equilibrium was gradual. The numerical simulations determined the dependence of the wave-drag coefficients on the Froude number and the width-to-depth ratio for waves on wet beds and, separately, for waves on dry land. The simulations also reproduced the wave forces for the range of conditions observed in the laboratory.