Research Of Numerical Method For Computational Aeroacoustics

There are intrinsic differences between the characteristics and the objectives of computational aeroacoustics problems and typical CFD problems. In this paper, the numerical methods for computational aeroacousitcs were described , including high resolution CAA methods, artificial selective damping and high quality numerical boundary conditions. It is indispensable in analyzing dispersion and dissipation errors associated with wave propagation computations. It is pointed out that the dispersion-relation-preserving finite difference schemes and appropriate nonreflecting boundary conditions are of critical importance to numerical methods for aeroacoustics. For the problem of nonlinear acoustics, the resolution of high-order differencing must be improved. In order to get exact numerical solution, some numerical procedure should be developed to eliminate numerical oscillations with short wave-length, but the components of longer wavelengths are virtually unaffected.Cavity flow problems exist in many aerospace applications with a great engineering value and it is of significance to study the cavity flow in both theoretical aspects and engineering applications. The generation and radiation of aerodynamic sound from a low-speed unsteady flow over a two-dimensional automobile door cavity is simulated by using a source-extraction-based coupling method. In the coupling procedure, the unsteady cavity flow field is first computed solving RANS equations. The radiate sound is then computed by solving the acoustic equation with source terms extracted from the unsteady flow. A dispersion-relation-preserving (DRP), optimized, forthorder finite difference scheme is used in the acoustic solver. The result of the cavity noise is agree well with the reference paper.