Hybrid lattice-Boltzmann digital-waveguide simulation of wind instruments

Abstract

A hybrid lattice-Boltzmann digital-waveguide model is proposed to improve the efficiency of the computational aeroacoustics modeling of wind instruments. The nonlinear sound generator and the assumed linear resonator of a wind instrument are modeled separately using the lattice Boltzmann (LB) method and digital waveguide (DWG) method, correspondingly. Their coupling is achieved through the characteristic boundary condition, which breaks down the lattice Boltzmann solutions at the junction into separated traveling waves along different characteristic lines. The lattice Boltzmann solver then sends the outgoing acoustic wave to the digital waveguide, and receives the incoming acoustic wave to complete the boundary condition. Two examples are tested to demonstrate the validity of the proposed method, including a hybrid cylindrical pipe composed of two coupled cylindrical segments, one represented by LB and the other by DWG, and a hybrid single-reed instrument that comprises an LB mouthpiece-reed system and a DWG pipe.