階層型直交格子法を用いた線形化格子ボルツマン法による 一円柱周りの放射音解析

抄録

A benchmark problem, acoustic scattering analysis around a circular cylinder, is solved in order to show the applicability of lattice Boltzmann method (LBM) for a direct simulation of sound propagation with reflection, diffraction and interference. First, compressible Euler equation with sound source term is derived from lattice Boltzmann equation with sound source term in order to show the consistency between the equations. Next, the benchmark problem is analyzed using linearized version of lattice Boltzmann method (LLBM). The effects of physical viscosity and grid resolution on the directivity pattern of the sound pressure are evaluated. In order to investigate the independent effect of the grid resolutions at the propagation region, the body surface region and the sound source region, hierarchical Cartesian grid is developed on LLBM. It is found that grid resolutions at all three regions are important for the accurate acoustic simulation. By setting sufficient grid resolution at each region, good agreement is observed between the numerical result and the exact solution.