Large-Eddy Simulations of Stratified Atmospheric Boundary Layers: Comparison of Different Subgrid Models
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Large-Eddy Simulations of Stratified Atmospheric Boundary Layers: Comparison of Different Subgrid Models Srinidhi N. Gadde1
· Anja Stieren1
· Richard J. A. M. Stevens1
Received: 20 May 2020 / Accepted: 1 September 2020 © The Author(s) 2020
Abstract The development and assessment of subgrid-scale (SGS) models for large-eddy simulations of the atmospheric boundary layer is an active research area. In this study, we compare the performance of the classical Smagorinsky model, the Lagrangian-averaged scale-dependent (LASD) model, and the anisotropic minimum dissipation (AMD) model. The LASD model has been widely used in the literature for 15 years, while the AMD model was recently developed. Both the AMD and the LASD models allow three-dimensional variation of SGS coefficients and are therefore suitable to model heterogeneous flows over complex terrain or around a wind farm. We perform a one-to-one comparison of these SGS models for neutral, stable, and unstable atmospheric boundary layers. We find that the LASD and the AMD models capture the logarithmic velocity profile and the turbulence energy spectra better than the Smagorinsky model. In stable and unstable boundary-layer simulations, the AMD and LASD model results agree equally well with results from a high-resolution reference simulation. The performance analysis of the models reveals that the computational overhead of the AMD model and the LASD model compared to the Smagorinsky model is approximately 10% and 30% respectively. The LASD model has a higher computational and memory overhead because of the global filtering operations and Lagrangian tracking procedure, which can result in bottlenecks when the model is used in extensive simulations. These bottlenecks are absent in the AMD model, which makes it an attractive SGS model for large-scale simulations of turbulent boundary layers. Keywords Atmospheric boundary layer · Large-eddy simulations · Lagrangian scale-dependent model · Minimum dissipation model · Smagorinsky model
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Srinidhi N. Gadde [email protected] Physics of Fluids Group, Max Planck Center Twente for Complex Fluid Dynamics, J. M. Burgers Center for Fluid Dynamics, MESA+ Research Institute, University of Twente, P. O. Box 217, 7500 AE Enschede, The Netherlands
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1 Introduction Large-eddy simulation (LES) has been instrumental in the study of turbulence in the atmospheric boundary layer (ABL) (Moeng 1984; Andren et al. 1994; Albertson 1996). In LES, large-scale eddies are resolved, and the effects of the subgrid-scale (SGS) eddies are parametrized. The most widely used SGS parametrization is the Smagorinsky model, in which the model coefficients are derived from theoretical arguments and empirical formulations (Smagorinsky 1967). A significant disadvantage of the Smagorinsky model is that the SGS stresses are assumed to be universal, isotropic, and scale-invariant, which makes the model unsuitable for anisotropic flows such as ABL flows. To overcome the limitations of the Smagorinsky model, ad hoc wall dampin
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