A COMPRESSIBLE IMMERSED BOUNDARY METHOD FOR THE FLOW-INDUCED NOISE SIMULATION
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[Abstract] A numerical body force model of immersed boundary method is derived in this paper, to simulate the flow-induced noise from complex geometries by solving the compressible Navier-Stokes equations on a fixed Cartesian grid. To obtain the numerical form of the body force, a relevance matrix named “influence matrix” is constructed to accurately satisfy the no-slip wall boundary conditions via the Dirac delta function. The singularity of the Dirac delta function is eliminated by involving a smoothed approximation, both the low-storage Cholesky decomposition and preconditioned conjugate gradient methods for the highly sparse influence matrix are developed to solve the linear equations. The high-order finite difference schemes and nonlinear nonreflecting boundary conditions are employed. In order to validate the computational model, laminar flow around a circular cylinder is simulated. Both the flow and sound fields are compared with the previous results. Furthermore, the radiated sound fields from an oscillating circular cylinder in a uniform flow are studied. The relationship between the oscillating frequency and the radiated sound is presented. All these numerical studies exhibit the capacity of the proposed immersed boundary method to deal with the stationary or even moving wall boundary conditions in the computational aeroacoustics.