Computational Aeroacoustics Using the Generalized Lattice Boltzmann Equation

The overall objective of the proposed project is to develop a generalized lattice Boltzmann (GLB) approach as a potential computational aeroacoustics (CAA) tool for noise prediction thus contributing to NASA's goal of reducing noise levels of subsonic aircraft. Lattice Boltzmann equation (LBE) based simulations are attractive for CAA as they can handle very complex geometries and parallelize with excellent scalability. This enables efficient simulation of very large problems, such as airframe systems. The innovativeness of the proposed GLB method lies in employing multiple relaxation times to capture different hydrodynamic/acoustic modes accurately, in contrast to usual LBE solution methods using a single relaxation time for all modes. The GLB approach would enable higher fidelity CAA simulations as well as exhibit stability at higher Reynolds numbers. Multiple relaxation times can also enable represent turbulence better for large eddy simulation. In phase I, the feasibility of the GLB method will be evaluated by coding a 3D solver, including a subgrid scale turbulence model and multiblock grid refinement algorithms, with testing against several CAA benchmark problems. If successful, a validated package based on the GLB method interfaced to NASA pre/post processors, like CART3D, for complex geometries would be developed in Phase II.