A new tuning-free subgrid-scale model, termed locally averaged scale-dependent dynamic (LASDD) model, is developed and implemented in large-eddy simulations (LES) of stable boundary layers. The new model dynamically computes the Smagorinsky coefficient and the subgrid-scale Prandtl number based on the local dynamics of the resolved velocity and temperature fields. Overall, the agreement between...

The paper presents Large Eddy Simulations of plane channel flow at a friction Reynolds number of 180 and 395 with a block-structured Finite Volume method. Local grid refinement near the solid wall is employed in order to reduce the computational cost of such simulations or other simulations of wall-bounded flows. Different subgrid-scale models are employed and different expressions for the leng...

A new dynamical subgrid model for turbulent flow in the surface layer of the planetary boundary layer is presented. In this formulation, the flow is decomposed into small (subgrid) and large (resolved) scales in the spirit of large-eddy simulation. The subgrid model, however, is derived directly from the governing equations and involves no adjustable parameters. The evolution of the small scale...

Regional Climate Models (RCMs) are practical downscaling tools to yield regional climate information for assessing the impacts of climate variability and change. The Pacific Northwest National Laboratory (PNNL) RCM, based on the Penn State/NCAR Mesoscale Model (MM5), features a novel subgrid treatment of orographic precipitation for coupling climate, hydrologic, and ecologic processes at the wa...

The " local-equilibrium " hypothesis that assumes a local balance between the viscous dissipation and the subgrid-scale dissipation at the same physical location in turbulent flow has been commonly used for turbulence modeling. For example, based on the local equilibrium hypothesis, Germano et al. (1991) and Moin et al. (1991) developed dynamic procedures for determining the model coefficients ...

Mathematical regularization of the nonlinear terms in the Navier-Stokes equations is found to provide a systematic approach to deriving subgrid closures for numerical simulations of turbulent flow. By construction, these subgrid closures imply existence and uniqueness of strong solutions to the corresponding modeled system of equations. We will consider the large-eddy interpretation of two such...