Investigation of the interaction of tsunami waves and submerged obstacles of finite thickness in a hydrodynamic wave flume

This paper presents results of mathematical simulation of the interaction of long tsunami-like wave with a submerged obstacle in a wave flume. The calculations were performed using the OpenFOAM freeware package. The mathematical model included unsteady two-dimensional Navier-Stokes equations for an incompressible two-phase medium. The volume of fluid (VOF) method was used to indicate and evaluate the air–liquid interface.
The effects caused by the motion of a long wave with a specified amplitude over a submerged obstacle of various thicknesses were discussed in details. The wave amplitude, which is 30 times greater than the water depth, and the obstacle height stayed constant and corresponded to the conditions of maximum wave energy decrease. Numerical results show that the multiple vortex structures are formed behind the obstacle during the passage of the wave. The intensity of the vortex depends on the barrier size. The effectiveness of the submerged obstacle was estimated by evaluating the wave reflection and transmission coefficients using the energy integral method. The curves indicating a variation in the reflection and transmission coefficients due to the wave interaction with obstacles of different thicknesses have been obtained. Finally, it has been confirmed that the wave energy in this case can be reduced from 43 % to 55 % after the passage of the wave through the obstacle. This energy decrease is caused by the intense vortex generation behind the barrier.