LARGE EDDY SIMULATION OF TURBULENT CHANNEL FLOW USING DUGKS-LES

The mesoscopic-scheme-based large eddy simulation (LES) has emerged as an alternative approach to study turbulent flows. The discrete unified gas kinetic scheme (DUGKS) is a relatively newly developed mesoscopic method, and the realization of LES in DUGKS is still in its early stages. In this paper, a DUGKS-LES algorithm is proposed by coupling the standard off-wall Smagorinsky subgrid model and the Musker wall model. Firstly, the relation between the effective total stress and the non-equilibrium distribution function for LES within the DUGKS framework is derived. When solving the wall shear stress using the wall function, a rapid Newton iteration method is designed to ensure the convergence, by incorporating the approximate solution of the inverse problem. Finally, large eddy simulations of the turbulent channel flows at friction Reynolds numbers of 180, 395 and 950 are performed to validate the proposed DUGKS-LES method. Compared with the results from the spectral method, the mean square errors of turbulence statistics such as streamwise velocity, Reynolds stress and fluctuating velocity are maintained below 11%. In the DUGKS framework, when compared with the wall-adapting subgrid models used in the literature, the proposed DUGKS-LES method incorporating the Musker wall model can achieve more precise results in terms of mean streamwise velocity and Reynolds shear stress.