Modal wave decoherence within a fluid layer with a rough surface
Résumé
The aim of the presentation is to study analytically the propagation of modal waves (like Lamb waves) in a rough fluid
plate, in order to interpret the decay of Lamb modes which are observed experimentally and theoretically in solid plates
with a rough interface. The analytical method employed here uses modal wave expansion, expressing locally the
roughness as an operator acting on the acoustic pressure. The expansion coefficient corresponding to a given modal
wave can be expressed as the sum of the direct field when interfaces are rigid plane (without roughness) and of a
diffused field created by the mode coupling due to the roughness.