A non-linear subgrid-scale model in LES of turbulent duct flow

Large-eddy simulation (LES) of turbulent duct flow is performed at bulk Reynolds number 𝑅𝑒=۲۵۰۰ using the explicit algebraic subgrid-scale (SGS) stress model (EASSM), which is a nonlinear SGS model. The aim of the current study is to investigate the effect of the SGS modeling in turbulent duct flow. LESs are performed using a second-order finite-volume solver at three different grid resolutions. LES predictions using the EASSM are compared with those of the commonly-used dynamic Smagorinsky model (DSM) and direct numerical simulation (DNS) data. Turbulent statistics such as the wall shear stress, mean velocity and vorticity are analyzed. It is found that the EASSM predictions are in much better agreement with the DNS data than those of the DSM at all the resolutions and the Reynolds number considered. The DSM significantly under-predicts the wall shear stress, whereas the EASSM predictions are closer and less resolution dependent. The mean velocity and streamwise vorticity contours are also presented, for which a better prediction is observed for the EASSM than the DSM. The extremely better predictions of the EASSM, especially at coarse grid resolutions signifies the importance of the nonlinear term in the EASSM formulation.

کلیدواژه ها:

Large-eddy simulation ، turbulent duct flow ، non-linear subgrid-scale model