scholarly journals Large-eddy simulation of plume dispersion under various thermally stratified boundary layers

2014 ◽  
Vol 11 (1) ◽  
pp. 75-81 ◽  
Author(s):  
H. Nakayama ◽  
T. Takemi ◽  
H. Nagai
Keyword(s):  
Large Eddy Simulation ◽  
Boundary Layers ◽  
Atmospheric Stability ◽  
Spanwise Direction ◽  
Plume Dispersion ◽  
Convective Boundary ◽  
Gas Dispersion ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Les Model

Abstract. Contaminant gas dispersion in atmospheric boundary layer is of great concern to public health. For the accurate prediction of the dispersion problem, the present study numerically investigates the behavior of plume dispersion by taking into account the atmospheric stability which is classified into three types; neutral, stable, and convective boundary layers. We first proposed an efficient method to generate spatially-developing, thermally-stratified boundary layers and examined the usefulness of our approach by comparing to wind tunnel experimental data for various thermal boundary layers. The spreads of plume in the spanwise direction are quantitatively underestimated especially at large downwind distances from the point source, owing to the underestimation of turbulence intensities for the spanwise component; however, the dependence of the spanwise spreads to atmospheric stability is well represented in a qualitative sense. It was shown that the large-eddy simulation (LES) model provides physically reasonable results.

Representing Sheared Convective Boundary Layer by Zeroth- and First-Order-Jump Mixed-Layer Models: Large-Eddy Simulation Verification

2006 ◽  
Vol 45 (9) ◽  
pp. 1224-1243 ◽  
Author(s):  
David Pino ◽  
Jordi Vilà-Guerau de Arellano ◽  
Si-Wan Kim
Keyword(s):  
Large Eddy Simulation ◽  
Boundary Layers ◽  
Mixed Layer ◽  
Convective Boundary ◽  
First Order ◽  
Eddy Simulation ◽  
Jump Model ◽  
Large Eddy ◽  
Entrainment Zone ◽  
Convective Boundary Layers

Abstract Dry convective boundary layers characterized by a significant wind shear on the surface and at the inversion are studied by means of the mixed-layer theory. Two different representations of the entrainment zone, each of which has a different closure of the entrainment heat flux, are considered. The simpler of the two is based on a sharp discontinuity at the inversion (zeroth-order jump), whereas the second one prescribes a finite depth of the inversion zone (first-order jump). Large-eddy simulation data are used to provide the initial conditions for the mixed-layer models, and to verify their results. Two different atmospheric boundary layers with different stratification in the free atmosphere are analyzed. It is shown that, despite the simplicity of the zeroth-order-jump model, it provides similar results to the first-order-jump model and can reproduce the evolution of the mixed-layer variables obtained by the large-eddy simulations in sheared convective boundary layers. The mixed-layer model with both closures compares better with the large-eddy simulation results in the atmospheric boundary layer characterized by a moderate wind shear and a weak temperature inversion. These results can be used to represent the flux of momentum, heat, and other scalars at the entrainment zone in general circulation or chemistry transport models.

scholarly journals Atmospheric stability effect on subgrid-scale physics for large-eddy simulation

2001 ◽  
Vol 24 (9-10) ◽  
pp. 1085-1102 ◽  
Author(s):  
Fernando Porté-Agel ◽  
Markus Pahlow ◽  
Charles Meneveau ◽  
Marc B. Parlange
Keyword(s):  
Large Eddy Simulation ◽  
Atmospheric Stability ◽  
Subgrid Scale ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Stability Effect

scholarly journals Demistify: a large-eddy simulation (LES) and single-column model (SCM) intercomparison of radiation fog

2022 ◽  
Vol 22 (1) ◽  
pp. 319-333
Author(s):  
Ian Boutle ◽  
Wayne Angevine ◽  
Jian-Wen Bao ◽  
Thierry Bergot ◽  
Ritthik Bhattacharya ◽  
...  
Keyword(s):  
Large Eddy Simulation ◽  
Weather Prediction ◽  
Cloud Droplet ◽  
Droplet Size Distribution ◽  
Radiation Fog ◽  
Eddy Simulation ◽  
Cloud Droplet Size Distribution ◽  
Large Eddy ◽  
Single Column ◽  
Les Model

Abstract. An intercomparison between 10 single-column (SCM) and 5 large-eddy simulation (LES) models is presented for a radiation fog case study inspired by the Local and Non-local Fog Experiment (LANFEX) field campaign. Seven of the SCMs represent single-column equivalents of operational numerical weather prediction (NWP) models, whilst three are research-grade SCMs designed for fog simulation, and the LESs are designed to reproduce in the best manner currently possible the underlying physical processes governing fog formation. The LES model results are of variable quality and do not provide a consistent baseline against which to compare the NWP models, particularly under high aerosol or cloud droplet number concentration (CDNC) conditions. The main SCM bias appears to be toward the overdevelopment of fog, i.e. fog which is too thick, although the inter-model variability is large. In reality there is a subtle balance between water lost to the surface and water condensed into fog, and the ability of a model to accurately simulate this process strongly determines the quality of its forecast. Some NWP SCMs do not represent fundamental components of this process (e.g. cloud droplet sedimentation) and therefore are naturally hampered in their ability to deliver accurate simulations. Finally, we show that modelled fog development is as sensitive to the shape of the cloud droplet size distribution, a rarely studied or modified part of the microphysical parameterisation, as it is to the underlying aerosol or CDNC.

Sign in / Sign up

Export Citation Format

Share Document