Large-eddy simulation of pollutant dispersion in a cavity at fine grid resolutions

2018 ◽  
Vol 127 ◽  
pp. 127-137 ◽  
Author(s):  
Hideki Kikumoto ◽  
Ryozo Ooka
Keyword(s):  
Large Eddy Simulation ◽  
Pollutant Dispersion ◽  
Fine Grid ◽  
Eddy Simulation ◽  
Large Eddy

scholarly journals Vertically nested LES for high-resolution simulation of the surface layer in PALM (version 5.0)

2019 ◽  
Vol 12 (6) ◽  
pp. 2523-2538 ◽  
Author(s):  
Sadiq Huq ◽  
Frederik De Roo ◽  
Siegfried Raasch ◽  
Matthias Mauder
Keyword(s):  
Boundary Layer ◽  
Surface Layer ◽  
High Resolution ◽  
Large Eddy Simulation ◽  
Grid Resolution ◽  
Computational Power ◽  
Fine Grid ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Nesting Algorithm

Abstract. Large-eddy simulation (LES) has become a well-established tool in the atmospheric boundary layer research community to study turbulence. It allows three-dimensional realizations of the turbulent fields, which large-scale models and most experimental studies cannot yield. To resolve the largest eddies in the mixed layer, a moderate grid resolution in the range of 10 to 100 m is often sufficient, and these simulations can be run on a computing cluster with a few hundred processors or even on a workstation for simple configurations. The desired resolution is usually limited by the computational resources. However, to compare with tower measurements of turbulence and exchange fluxes in the surface layer, a much higher resolution is required. In spite of the growth in computational power, a high-resolution LES of the surface layer is often not feasible: to fully resolve the energy-containing eddies near the surface, a grid spacing of O(1 m) is required. One way to tackle this problem is to employ a vertical grid nesting technique, in which the surface is simulated at the necessary fine grid resolution, and it is coupled with a standard, coarse, LES that resolves the turbulence in the whole boundary layer. We modified the LES model PALM (Parallelized Large-eddy simulation Model) and implemented a two-way nesting technique, with coupling in both directions between the coarse and the fine grid. The coupling algorithm has to ensure correct boundary conditions for the fine grid. Our nesting algorithm is realized by modifying the standard third-order Runge–Kutta time stepping to allow communication of data between the two grids. The two grids are concurrently advanced in time while ensuring that the sum of resolved and sub-grid-scale kinetic energy is conserved. We design a validation test and show that the temporally averaged profiles from the fine grid agree well compared to the reference simulation with high resolution in the entire domain. The overall performance and scalability of the nesting algorithm is found to be satisfactory. Our nesting results in more than 80 % savings in computational power for 5 times higher resolution in each direction in the surface layer.

Large-Eddy Simulation of Reactive Pollutant Dispersion Over Street Canyons of Different Aspect Ratios

2014 ◽  
Author(s):  
T. Z. Du ◽  
Chun-Ho Liu ◽  
Y. B. Zhao
Keyword(s):  
Aspect Ratio ◽  
Large Eddy Simulation ◽  
Chemical Reactions ◽  
Pollutant Dispersion ◽  
Pollutant Removal ◽  
Street Canyons ◽  
Eddy Simulation ◽  
Aspect Ratios ◽  
Large Eddy ◽  
Reactive Pollutant

In urban areas, pollutants are emitted from vehicles then disperse from the ground level to the downstream urban canopy layer (UCL) under the effect of the prevailing wind. For a hypothetical urban area in the form of idealized street canyons, the building-height-to-street-width (aspect) ratio (AR) changes the ground roughness which in turn leads to different turbulent airflow features. Turbulence is considered an important factor for the removal of reactive pollutants by means of dispersion/dilution and chemical reactions. Three values of aspect ratio, covering most flow scenarios of urban street canyons, are employed in this study. The pollutant dispersion and reaction are calculated using large-eddy simulation (LES) with chemical reactions. Turbulence timescale and reaction timescale at every single point of the UCL domain are calculated to examine the pollutant removal. The characteristic mechanism of reactive pollutant dispersion over street canyons will be reported in the conference.

Large eddy simulation of pollutant dispersion in a naturally cross-ventilated model building: Comparison between sub-grid scale models

2019 ◽  
Vol 12 (5) ◽  
pp. 921-941 ◽  
Author(s):  
Farzad Bazdidi-Tehrani ◽  
Shahin Masoumi-Verki ◽  
Payam Gholamalipour ◽  
Mohsen Kiamansouri
Keyword(s):  
Large Eddy Simulation ◽  
Model Building ◽  
Pollutant Dispersion ◽  
Eddy Simulation ◽  
Scale Models ◽  
Large Eddy

Model Sensitivity Test of Large Eddy Simulation for Wind Flow and Pollutant Dispersion in a Street Canyon

2014 ◽  
Vol 695 ◽  
pp. 562-566
Author(s):  
Afiq Witri Muhammad Yazid ◽  
Nor Azwadi Che Sidik ◽  
Salim Mohamed Salim ◽  
Shuhaimi Mansor
Keyword(s):  
Steady State ◽  
Large Eddy Simulation ◽  
Street Canyon ◽  
Pollutant Dispersion ◽  
Wind Flow ◽  
Model Sensitivity ◽  
Ansys Fluent ◽  
Urban Street ◽  
Eddy Simulation ◽  
Large Eddy

This paper reports on the model sensitivity analysis of a commercial computational fluid dynamics program, ANSYS FLUENT v14. The purpose of the analysis was to determine the appropriate modeling settings for numerical model of the case study. A full scale of a simplified urban street canyon was modelled and the turbulent flow was calculated using Large Eddy Simulation (LES) techniques. The model sensitivity tests involved are mesh sensitivity, statistically steady state and sampling. Adequate numbers of cells, period time to achieve statistically steady state (SST) and sampling time to simulate wind flow and pollutant dispersion in street canyon were determined through systematic tests.

Large-eddy simulation of vortex streets and pollutant dispersion behind high-rise buildings

2017 ◽  
Vol 143 (708) ◽  
pp. 2714-2726 ◽  
Author(s):  
Beom-Soon Han ◽  
Seung-Bu Park ◽  
Jong-Jin Baik ◽  
Junho Park ◽  
Kyung-Hwan Kwak
Keyword(s):  
Large Eddy Simulation ◽  
Pollutant Dispersion ◽  
High Rise ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Vortex Streets
Sign in / Sign up

Export Citation Format

Share Document