A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Eulerian RANS simulations of near-field pollutant dispersion around buildings using concentration diffusivity limiter with travel time
Abstract To improve the prediction accuracy of pollutant dispersion near a source, a limiter for turbulent concentration diffusivity accounting for pollutant travel time is introduced into the Reynolds-averaged Navier–Stokes equations (RANS) and the Eulerian dispersion model. We predict pollutant dispersion in a two-dimensional street canyon and three-dimensional building arrays via the conventional modeling of turbulent diffusivity based on a simplified gradient diffusion hypothesis and the limiter. The results are validated using data from a wind tunnel experiment. Conventional modeling with yields results similar to experimental results. However, the mean concentration near the source is underestimated. The limiter reduces the turbulent diffusivity near the source by adjusting the combination of model parameters and improves the accuracy of concentration prediction. Based on the result with the limiter, we discovered that the turbulent Schmidt number near the source by the conventional definition can exceed three times that in the downwind region. Finally, we discuss the effect of the limiter on the net mass fluxes in pollutant removal. For the building arrays, the limiter increases the advective mass flux near the source and transports more pollutants toward the leeward wall, thereby decreasing the surface-sum spanwise turbulent-mass-flux at the source-located canyon side.
Highlights RANS simulations were conducted and validated for near-field gas dispersion. A limiter for turbulent concentration diffusivity based on pollutant travel time was introduced. The limiter reduces the turbulent diffusivity near the source and improves the concentration prediction accuracy. near the source by the conventional definition can exceed three times that in the downwind region.
Eulerian RANS simulations of near-field pollutant dispersion around buildings using concentration diffusivity limiter with travel time
Abstract To improve the prediction accuracy of pollutant dispersion near a source, a limiter for turbulent concentration diffusivity accounting for pollutant travel time is introduced into the Reynolds-averaged Navier–Stokes equations (RANS) and the Eulerian dispersion model. We predict pollutant dispersion in a two-dimensional street canyon and three-dimensional building arrays via the conventional modeling of turbulent diffusivity based on a simplified gradient diffusion hypothesis and the limiter. The results are validated using data from a wind tunnel experiment. Conventional modeling with yields results similar to experimental results. However, the mean concentration near the source is underestimated. The limiter reduces the turbulent diffusivity near the source by adjusting the combination of model parameters and improves the accuracy of concentration prediction. Based on the result with the limiter, we discovered that the turbulent Schmidt number near the source by the conventional definition can exceed three times that in the downwind region. Finally, we discuss the effect of the limiter on the net mass fluxes in pollutant removal. For the building arrays, the limiter increases the advective mass flux near the source and transports more pollutants toward the leeward wall, thereby decreasing the surface-sum spanwise turbulent-mass-flux at the source-located canyon side.
Highlights RANS simulations were conducted and validated for near-field gas dispersion. A limiter for turbulent concentration diffusivity based on pollutant travel time was introduced. The limiter reduces the turbulent diffusivity near the source and improves the concentration prediction accuracy. near the source by the conventional definition can exceed three times that in the downwind region.
Eulerian RANS simulations of near-field pollutant dispersion around buildings using concentration diffusivity limiter with travel time
Lin, Chao (author) / Ooka, Ryozo (author) / Kikumoto, Hideki (author) / Jia, Hongyuan (author)
Building and Environment ; 202
2021-06-08
Article (Journal)
Electronic Resource
English
Different Methods to Compute Pollutant Dispersion Around Buildings
| British Library Conference Proceedings | 1994