Large-Eddy Simulation of smooth and rough channel flows using a one-dimensional stochastic wall model

In this study a stochastic wall model based on the ''large-eddy'' version of the One-Dimensional Turbulence (ODT) model was developed for Large-Eddy Simulation (LES) of smooth and rough channel flows, with the primary goal of providing a refined turbulent flow field near the wall. This LES-ODT coupling was tested with the dynamic Smagorinsky and the scale-dependent Lagrangian dynamic subgrid-scale models. When compared to the same LES with a wall model based on a local law-of-the-wall, LES-ODT improved the one-dimensional energy spectra for all three velocity components close to the wall for both subgrid-scale models tested. More importantly, improving the LES wall model had a more positive effect in the near-wall spectra than improving the subgrid-scale model from the traditional dynamic to the scale-dependent Lagrangian dynamic model. For smooth channels, LES-ODT results compared well with DNS of Re-lambda = 590 and 5200; however, the variance modeled by the ODT presents discrepancies for all three velocity components, an issue inherent to ODT. Finally, the simulation of a channel flow with additional roughness modeled by a drag force was compared to data of atmospheric flow through a maize field, providing evidence of the potential for this approach to directly simulate complex near-wall phenomena. Given its high computational cost, the main use of the LES-ODT coupling is in studies that require a refinement of the near-wall region without the need to refine the entire LES domain.

Automated summary

A stochastic wall model based on the ODT model was developed for LES of smooth and rough channel flows, providing a refined turbulent flow field near the wall. The LES-ODT coupling improved the one-dimensional energy spectra for all three velocity components close to the wall, showing more positive effects in the near-wall spectra than improving the subgrid-scale model. The high computational cost of LES-ODT limits its main use to studies requiring refinement of the near-wall region without the need to refine the entire LES domain.