CFD Simulations of Flow and Dispersion under Construction Disturbance ConditionsChinese Full Text
LI Qin-yi,CAI Xu-hui,KANG Ling State Joint Key Lab of Environmental Simulation and Pollution Control,College of Environmental Sciences and Engineering,Peking University,Beijing 100871,China
Abstract: Researches of flow and dispersion in urban area are important to meet the practical demands of studies of vehicular exhaust pollution and accidental leakage.Numerical simulations with field observations and physical simulations（e.g.,wind tunnel simulation） are often used to address atmospheric flow and dispersion problems in cities.In general,numerical simulations can provide specific detailed informations of flow,turbulence and dispersion.To deal with small-scaled flow and dispersion,computational fluid dynamics（CFD） models are widely applied and are capable of reproducing small-scaled characteristics of flow and dispersion.A CFD model-FLUENT was adopted to simulate the disturbance of a single building on atmospheric flow under the neutral stability condition.Wind tunnel data published by Hamburg University was collected to validate the modeled results and assess the choices of parameters and parameterization schemes.This technique was applied to address atmospheric dispersion problems in quasi-urban building arrays.Concentration data of MUST and a tracer experiment were used to evaluate the dispersion modeling.The results indicated that FLUENT well performed in mean flow simulation under construction disturbance condition.Simulated results for FAC2 of horizontal and vertical modeling wind speed were 77.9% and 61.0% respectively.However,thre was a relatively larger discrepancy between the modeling and measured turbulence characteristics,when the FAC2 of modeling turbulent kinetic energy was 54.6%.The turbulent closure scheme options（i.e.,standard K-ε scheme,Re-normalization Group K-ε scheme and Reynolds Stress Model scheme） had trivial effects on simulated results.The dispersion simulation case within quasi-urban buildings was satisfactory.The result of the dispersion case correctly reproduced the irregular plume shifting caused by building disturbance compared to the average wind direction.The modeling concentrations were generally in accordance with measured results,and the relative tolerance of the modeling maximum concentration in lateral profile at 32 and 63 m downwind were 72.5% and 36.9% respectively.Relative to the Gaussian plume model-ISC3,FLUENT can provide more practical concentration distribution under complex conditions.FLUENT simulation also indicated that the maximum lateral concentration decreased along the downwind direction in "step change" pattern between the adjacent street canyons near the release source.The maximum lateral pollutant concentrations in the same street canyon as the source were several times or even one order of magnitude higher than that in the next canyon.FLUENT results can reproduce the phenomena of dispersion towards upwind area and also of accumulation and detouring flow around the constructions.Further researches are required to analyze the phenomena.
- DOI：
10.13198/j.res.2013.08.26.liqy.009
- Series：
- Subject：
- Classification Code：
X511
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