232728
20181203024904.0
0006-8314
10.1007/s10546-017-0287-5
doi
000415143200001
ISI
ARTICLE
A Modulated-Gradient Parametrization for the Large-Eddy Simulation of the Atmospheric Boundary Layer Using the Weather Research and Forecasting Model
Dordrecht
2017
Springer
2017
20
Journal Articles
The performance of the modulated-gradient subgrid-scale (SGS) model is investigated using large-eddy simulation (LES) of the neutral atmospheric boundary layer within the weather research and forecasting model. Since the model includes a finite-difference scheme for spatial derivatives, the discretization errors may affect the simulation results. We focus here on understanding the effects of finite-difference schemes on the momentum balance and the mean velocity distribution, and the requirement (or not) of the ad hoc canopy model. We find that, unlike the Smagorinsky and turbulent kinetic energy (TKE) models, the calculated mean velocity and vertical shear using the modulated-gradient model, are in good agreement with Monin-Obukhov similarity theory, without the need for an extra near-wall canopy model. The structure of the near-wall turbulent eddies is better resolved using the modulated-gradient model in comparison with the classical Smagorinsky and TKE models, which are too dissipative and yield unrealistic smoothing of the smallest resolved scales. Moreover, the SGS fluxes obtained from the modulated-gradient model are much smaller near the wall in comparison with those obtained from the regular Smagorinsky and TKE models. The apparent inability of the LES model in reproducing the mean streamwise component of the momentum balance using the total (resolved plus SGS) stress near the surface is probably due to the effect of the discretization errors, which can be calculated a posteriori using the Taylor-series expansion of the resolved velocity field. Overall, we demonstrate that the modulated-gradient model is less dissipative and yields more accurate results in comparison with the classical Smagorinsky model, with similar computational costs.
Atmospheric boundary layer
Large-eddy simulation
Subgrid-scalemodelling
Weather Research and Forecasting model
Khani, Sina
Ecole Polytech Fed Lausanne, Wind Engn & Renewable Energy Lab WiRE, CH-1015 Lausanne, Switzerland
256546
249094
Porte-Agel, Fernando
Ecole Polytech Fed Lausanne, Wind Engn & Renewable Energy Lab WiRE, CH-1015 Lausanne, Switzerland
168244
243661
385-404
3
Boundary-Layer Meteorology
165
WIRE
252260
U12172
oai:infoscience.tind.io:232728
ENAC
article
168244
EPFL-ARTICLE-232728
EPFL
PUBLISHED
REVIEWED
ARTICLE