Study on Anisotropy in Synthetic Turbulence Generation Methods
M. Kamruzzaman, Th. Lutz and E. Krämer, extended abstract submitted to AIAA/CEAS Aeroacoustics Conference, June, 2012
This paper focuses on the possible extension and improvement of existing stochastic methods to synthesize time dependent anisotropic turbulence for the flow-induced broadband noise prediction models. Three different stochastic approaches are investigated, namely, Random Flow Generation (RFG) approach, Random Particle Mesh (RPM) method and Synthetic Eddy Method (SEM). The basic theories and applied numerical algorithms of these methods for the generation of isotropic-homogeneous turbulence field are discussed elaborately together with the new length scale theory in anisotropic extension. Steady RANS computations are performed for high Reynolds number flow, and for the assessment of the stochastic methods, the turbulent boundary-layer near the airfoil trailing-edge noise source region is investigated. Prediction data of various turbulence properties such as one-dimensional velocity spectra, two-point space-time correlation functions and integral length scales are validated with available wind tunnel measurement. Results are investigated critically with detail discussion. Necessary improvements and limitations are outlined.