Tsunami-Height Reduction Using a Very Large Floating Structure

Abstract

The tsunami-height reduction using a very large floating structure (VLFS) is discussed, where water waves, interacting with a floating thin plate, are simulated through a numerical model, based on a variational principle, including the nonlinearity and dispersion of waves. First, the tsunami height decreases owing to the wave disintegration, with a creation of shorter floating-body waves of larger phase velocities. Second, after passing the VLFS, the main wave overlaps the shorter waves in the uncovered area, such that the tsunami height increases. Finally, the tsunami height decreases again, as the main wave leaves the shorter waves behind. The final tsunami-height reduction rate increases, as the length or the flexural rigidity of the VLFS is increased. When the VLFS flexural rigidity is larger, it takes a longer time for the VLFS to obtain the final tsunami-height reduction rate.