A Modulated-Gradient Parametrization for the Large-Eddy Simulation of the Atmospheric Boundary Layer Using the Weather Research and Forecasting Model

2017 ◽  
Vol 165 (3) ◽  
pp. 385-404 ◽  
Author(s):  
Sina Khani ◽  
Fernando Porté-Agel
Keyword(s):  
Boundary Layer ◽  
Large Eddy Simulation ◽  
Atmospheric Boundary Layer ◽  
Weather Research And Forecasting ◽  
Forecasting Model ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Weather Research

scholarly journals Transition and Equilibration of Neutral Atmospheric Boundary Layer Flow in One-Way Nested Large-Eddy Simulations Using the Weather Research and Forecasting Model

2013 ◽  
Vol 141 (3) ◽  
pp. 918-940 ◽  
Author(s):  
Jeff Mirocha ◽  
Gokhan Kirkil ◽  
Elie Bou-Zeid ◽  
Fotini Katopodes Chow ◽  
Branko Kosović
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Large Eddy Simulations ◽  
Single Domain ◽  
Surface Velocity ◽  
Weather Research And Forecasting ◽  
Forecasting Model ◽  
Near Surface ◽  
Large Eddy ◽  
Weather Research

Abstract The Weather Research and Forecasting Model permits finescale large-eddy simulations (LES) to be nested within coarser simulations, an approach that can generate more accurate turbulence statistics and improve other aspects of simulated flows. However, errors are introduced into the finer domain from the nesting methodology. Comparing nested domain, flat-terrain simulations of the neutral atmospheric boundary layer with single-domain simulations using the same mesh, but instead using periodic lateral boundary conditions, reveals the errors contributed to the nested solution from the parent domain and nest interfaces. Comparison of velocity spectra shows good agreement among higher frequencies, but greater power predicted on the nested domain at lower frequencies. Profiles of mean wind speed show significant near-surface deficits near the inflow boundaries, but equilibrate to improved values with distance. Profiles of the vertical flux of x momentum show significant underprediction by the nested domain close to the surface and near the inlet boundaries. While these underpredictions of the stresses, which cause the near-surface velocity deficits, attenuate with distance within the nested domains, significant errors remain throughout. Profiles of the resolved turbulence kinetic energy show considerable deviations from their single-domain values throughout the nested domains. The authors examine the accuracy of these parameters and their sensitivities to the turbulence subfilter stress model, mesh resolution, and grid aspect ratio, and provide guidance to practitioners of nested LES.

scholarly journals Large-eddy simulation of turbulent flows over an urban building array with the ABLE-LBM and comparison with 3D MRI observed data sets

2020 ◽  
Author(s):  
Yansen Wang ◽  
Michael J. Benson
Keyword(s):  
Boundary Layer ◽  
Kinetic Energy ◽  
Large Eddy Simulation ◽  
Atmospheric Boundary Layer ◽  
Validation Study ◽  
Tall Building ◽  
Turbulent Wind ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Building Array

Abstract In this article we describe the details of an ABLE-LBM (Atmospheric Boundary Layer Environment-Lattice Boltzmann Model) validation study for urban building array turbulent flow simulations. The ABLE-LBM large-eddy simulation results were compared with a set of 3D magnetic resonance image (MRI) velocimetry data. The ABLE-LBM simulations used the same building layout and Reynolds numbers operated in the laboratory water channel. The building set-up was an evenly spaced orthogonal array of cubic buildings (height = H) with a central tall building (height = 3H) in the second row. Two building orientations, angled with 0°and 45° wind directions, were simulated with ABLE-LBM. The model produced horizontal and vertical fields of time-averaged velocity fields and compared well with the experimental results. The model also produced urban canyon flows and vortices at front and lee sides and over building tops that were similar in strength and location to the laboratory studies. The turbulent kinetic energy associated with these two wind directions were also presented in this simulation study. It is shown that the building array arrangement, especially the tall building, has a great effect on turbulent wind fields. There is a Karman vortex street on the lee side of the tall building. High turbulent intensity areas are associated with the vortex shedding motions at building edges. In addition, the wind direction is a very important factor for turbulent wind and kinetic energy distribution. This validation study indicated that ABLE-LBM is a viable simulation model for turbulent atmospheric boundary layer flows in the urban building array. The computational speed of ABLE-LBM using the GPU has shown that real-time LES simulation is realizable for a computational domain with several millions grid points.

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