Numerical Methods in Computational Aeroacoustics (CAA)

Course content

Student have in depth knowledge in the area of numerical aeroacoustics. Students are in a position to apply CAA (= Computational Aeroacoustics) methods for the solution of engineering science problems; they know the basic equations as a foundation of the methods along with the numerical algorithms for their solution. Students can chose among the various simulation concepts the most appropriate for the solution of a given aeroacoustic problem. Students have the qualification to tie in with the state of the development of CAA methods and to advance these. Students may critically assess results of CAA simulations. The excursion conveys to the students the practical use of experimental methods to measure sound generated aerodynamically. The contents put students into the position to further elaborate on the experimental methods presented in the lecture and to recognize the meaning of the aeroacoustic experiment as the basis for the validation of the computational methods.

Course content:

Basic equation of aeroacoustics, dispersion relation, numerical discretization by means of finite differences, stability and von Neumann method, dispersion relation preserving schemes of high order on structured computation grids, formulation of equations on curvi-linear structured grids, low dissipation and dispersion Runge-Kutta methods, damping and filtering of non-physical waves, highly accurate non-reflecting boundary conditions, overview about CAA methods for non-structured grids, particularly Discontinuous Galerkin FE scheme, stochastic and deterministic source description for CAA, Integral methods for the extrapolation of simulation data to the farfield. The session in the acoustic wind tunnel Braunschweig (AWB) encompasses the a) Explanation of the composition of an acoustic wind tunnel exemplified at the AWB, particularly the technologies for the generation of a silent air flow; the classical wind tunnel corrections, adapted to the settings in the AWB are shown in concrete example cases b) Demonstration of various measurement techniques in aeroacoustics c) Demonstration of measurement arrangements for the experimental determination of sound sources and sound radiation as well as for the validation of numerical methods of aeroacoustics, e.g. airfoil trailing edge noise, Aeolian tones of a vortex shedding cylinder, noise reduction techniques.