An interpolation-bounce-immersed boundary lattice Boltzmann method for fluid-structure-acoustic simulation applied to elastic airfoil trailing edge

Abstract

This paper presents a direct numerical simulation of fluid-structure-acoustic multi-physics coupling for an airfoil with an elastic trailing edge at the intermediate to high Reynolds numbers using the lattice Boltzmann method (LBM). When dealing with a moving boundary, a modified immersed boundary method (IBM) based on velocity correction and incorporating interpolated bounce back (IBB) is proposed. This method aims to capture the small pressure perturbations caused by solid vibrations through high-precision IBM for acoustic calculations at high Reynolds numbers. The method was validated by cantilever and NACA0012 airfoil cases, demonstrating its ability to simulate fluid-structure-acoustic coupling. A comparison between elastic trailing edge noise results with different elastic moduli and rigid trailing edge noise showed a decrease in low-frequency discrete tonal noise and an increase in high-frequency broadband noise, confirming the effectiveness of the method in simulating noise reduction with elastic trailing edges. Frequency domain analysis of the acoustic field results was conducted using DMD, confirming the physical nature of small perturbation waves, explaining the noise reduction mechanism, and validating the accuracy of the method in simulating small perturbation waves with elastic trailing edges.