Large eddy simulations of low-mach number aeroacoustics for complex wall-bounded turbulent flows via a multiblock/characteristic interface approach

Efficient computational aeroacoustics of low-speed, wall-bounded turbulent flows based on the large eddy simulation (LES) technique using a high-order, semi-implicit multiblock approach are presented. Characteristics-based interface conditions that accurately respect acoustic wave propagation are used for communication between the adjacent computational blocks. The multiblock approach requires only one overlap node per block allowing for more efficient handling of complex geometries. The accuracy and efficiency of the present approach is assessed by a simple acoustic model problem and by comparing LES predictions for turbulent separated flow in an asymmetric diffuser to previously published single-block results. The multiblock results shown good wave propagation capabilities are in reasonable agreement with single block computations for both mean velocities and turbulence statistics. Aeroacoustic accuracy is assessed by comparing direct simulations of far-field sound to Ffowcs Williams - Hawkings acoustic analogy predictions for the case of pulsatile flow through a duct with either a convergent or divergent orifice. Direct sound computations and acoustic analogy predictions are in good agreement.