A Generalized Corcos model for the prediction of the coherence function in turbulent boundary layers with zero and adverse pressure gradient

An important quantity in the simulation of turbulent flow is the spanwise coherence of the turbulence field. For the purpose of noise prediction, the coherence represents, in a statistical sense, the size of a source region that radiates independently from nearby sources. Its description is fundamental for an accurate assessment of the sound radiated. This paper focuses on the calculation of the coherence functions at four points of the suction side of a controlled diffusion airfoil characterized by zero and adverse pressure gradients, respectively. A novel analytical model defined as the Generalized Corcos model, which is based on a generalization of the classical Corcos, is used for the characterization of the streamwise and spanwise coherence. Its accuracy is analyzed considering a direct numerical simulation of the flow over the airfoil under the same conditions. This work shows how it is possible to correctly predict the DNS coherence function when the Generalized Corcos model is used.