Physical Modeling of Sea‐Seabed Interactions

Abstract

A Froude‐Mach similitude law for sea‐seabed interaction phenomena is established from the nonlinear Coulomb‐damped poro‐elastic theory recently developed. Generally, the similitude law requires that the three Mach numbers which are the ratios of water wave phase velocity to those of the fast and slow compressional waves and the shear waves in the seabed should be equalized in the prototype situation and the physical scale model in addition to the Froude number and the geometrical similarity. Laboratory wave tank experiments using sand beds and clay beds substantiate the theoretical similitude law. It is found that the response of sand beds to water waves is linear and quasistatic. The effect of the Coulomb friction in sand beds on wave attenuation is usually larger than that of percolation of pore water through sand beds. The response of clay beds to water waves is highly nonlinear and dynamically amplified. The Coulomb friction in clay beds is by far the largest wave damping mechanism compared to other damping mechanisms.