Dynamic Hybrid RANS/LES Assessment of Sound Generation and Propagation from Flow of a Circular Cylinder

Wang, X., Bhushan, S., Mansoor, B., Luke, E., Sescu, A., Hattori, Y., Thompson, D., & Walters, K. (2018). Dynamic Hybrid RANS/LES Assessment of Sound Generation and Propagation from Flow of a Circular Cylinder. 2018 AIAA/CEAS Aeroacoustics Conference, AIAA AVIATION Forum, (AIAA 2018-3592). Atlanta, GA: AIAA. DOI:10.2514/6.2018-3592.

This work conducted high fidelity computational simulations of cross flow over a circular cylinder for flows in various representative regimes. The objective of this research is to evaluate the performance and effectiveness of a dynamic hybrid RANS/LES (DHRL) turbulence model for capturing sound generation and propagation in order to improve acoustics prediction. This physical-based DHRL modelling framework relies on the statistical processing of the evolving flow field over time to improve model constants and adjust the RANS-LES transition zone in a manner that ensures continuity of turbulence production and provides a seamless coupling between RANS and LES regions. For comparison purpose, direct numerical simulation (DNS), RANS simulation using Menter’s shear stress transport (SST) model, and SST-based large eddy simulation (LES) are evaluated as well. The DNS simulation is conducted using a structured flow solver with a 6th order compact scheme for spatial derivatives and a 4th order Runge-Kutta method for time marching. Simulations of RANS, LES and DHRL used an unstructured flow solver coupled with an optimization gradient reconstruction (OGRE) low-dissipation scheme. Analysis of the simulation solutions will attempt to address some key issues in computational aeroacoustics, regarding physical modeling of turbulence in various models, adequate grid resolution for capturing the full range of turbulence structures, and numerical algorithms for reducing numerical dissipation and dispersion.