  In this study, the numerical analysis of a specific fluid-solid interaction
problem is detailed. The weakly nonlinear Boussinesq system is considered with
the addition of a solid object lying on the flat bottom, allowed to move
horizontally under the pressure forces created by the waves. We present an
accurate finite difference scheme for this physical model, finely tuned to
preserve important features of the original coupled system: nonlinear effects
for the waves, energy dissipation due to the frictional movement of the solid.
The moving bottom case is compared with a system where the same object is fixed
to the bottom in order to observe the qualitative and quantitative differences
in wave transformation. In particular a loss of wave amplitude is observed. The
influence of the friction on the whole system is also measured, indicating
differences for small and large coefficients of friction. Overall, hydrodynamic
damping effects reminiscent to the dead-water phenomenon can be established.
