A Lattice-Boltzmann method for the interaction between mechanical waves and solid mobile bodies

The acoustic waves generated by moving bodies and the movement of bodies by acoustic waves are central phenomena in the operation of musical instruments and in everyday's experiences like the movement of a boat on a lake by the wake generated by a propelled ship. Previous works have successfully simulated the interaction between a moving body and a lattice-Boltzmann fluid by immersed boundary methods. Hereby, we show how to implement the same coupling in the case of a Lattice-Boltzmann for waves, i.e. a LBGK model that directly recovers the wave equation in a linear medium, without modeling fluids. The coupling is performed by matching the displacement at the medium-solid boundary and via the pressure, which characterizes the forces undergone by the medium and the immersed body. The proposed model simplifies the preceeding immersed boundary methods and reduces the calculations steps. The method is illustrated by simulating the movement of immersed bodies in two dimensions, like the displacement of a two-dimensional disk due to an incoming wave or the wake generated by a moving object in a medium at rest. The proposal consitutes a valuable tool for the study of acoustical waves by lattice-Boltzmann methods.