Application of the stretched-vortex subgrid-scale model to large-eddy simulation of the cloud-topped atmospheric boundary layer

The stretched-vortex model is a structural large-eddy simulation (LES) turbulence closure that incorporates turbulence flow physics ideas, considering the turbulent region as an ensemble of vortex filaments with their own dynamical statistics. Averaging these vortex filaments produces the subgrid stresses. The stretched-vortex subgrid scale (SGS) model is adapted for simulations of the atmospheric boundary layer by a buoyancy-adjusted extension that takes into account the anisotropy of the subgrid-scale mixing in stratified conditions. Simulations of a trade-wind cumulus-topped boundary layer are performed and compared with predictions of the Smagornisky SGS model. Results obtained with the stretched-vortex model exhibit good resolution independence, even at coarse grid resolutions, while the Smagorinsky closure does not yield a resolution-independent solution.