APS -70th Annual Meeting of the APS Division of Fluid Dynamics- Event - A near-wall model from analysis of inner-outer interactions in filtered wall bounded turbulence

摘要

Large Eddy Simulations (LES) directly represent larger scale turbulent motionsand model the effects of small scale motions. However in the near-wall regionthe large dynamically important eddies scale in viscous wall units, which makesresolving them in a high Reynolds number LES very expensive. This motivates theuse of wall-modeled LES, in which these near-wall eddies are modeled. To aidin the development of new wall models, we pursue an asymptotic analysis of thefiltered Navier-Stokes equations, in the limit in which the horizontal filterscale is large compared to the thickness of the wall layer. We show that inthis limit the filtered velocities $ar{u}$ in the near-wall layer aredetermined to zeroth order by filtered velocities at the boundary of the walllayer. Further, the asymptotics suggest that there is a scaled universalvelocity profile $f$ in the near-wall region. The profile $f$ is evaluatedthrough analysis of DNS data from channel flow at $Re_{au}=5200$. We use theresulting profile $f$ to formulate a predictive near-wall model. The modeldepends only on the filtered velocities at the boundary of the near-wall layerand can supply boundary conditions for a wall-modeled LES. We presentpreliminary results from a coarse LES using this wall model.