Large-eddy simulation of dispersion in the convective boundary layer |
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| Institution: | 1. School of Mechanical Engineering, KIIT University, Bhubaneswar, Odisha, India;2. School of Mechanical Sciences, IIT, Bhubaneswar, Odisha, India;1. ME Department, Dhahran 31261, Saudi Arabia;2. ME Department, KFUPM Box 1913, Dhahran 31261, Saudi Arabia;1. School of Urban Construction and Environmental Engineering, Chongqing University, Chongqing 400045, China;2. Key Laboratory of Low-grade Energy Utilization Technologies and Systems (Chongqing University), Ministry of Education of China, Chongqing 400044, China;3. Key Laboratory of the Three Gorges Reservoir Region’s Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China;4. College of Mechanical and Power Engineering, Chongqing University of Science & Technology, Chongqing 401331, China;1. School of Civil, Environmental, & Architectural Engineering, Korea University, Seoul, Korea;2. Arup, NY, USA;1. State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Xuzhou 221116, Jiangsu, PR China;2. School of Mechanics and Civil Engineering, China University of Mining and Technology, Xuzhou 221116, Jiangsu, PR China;3. Ludong University, Yantai 264025, Shandong, PR China |
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| Abstract: | Large-eddy simulation (LES) is used to study the dispersion of a passive scalar downwind of a localized source in a convective boundary layer. The LES turbulent velocity statistics are compared with laboratory data and other LES studies. Two scalar source heights at 0.25 zi and 0.50 zi are considered, where zi is the inversion height, and the mean concentration fields are compared with the experimental data of Willis and Deardorf (1978, Atmospheric Environment12, 1305–1312; 1981, Atmospheric Environment15, 109–117). Emphasis is placed on the fluctuating component of the concentration field due to the random turbulent velocity fluctuations, and amplitudes, temporal and spatial scales, and probability distributions are examined. Concentration fluctuation intensity continually decreases downstream, suggesting zero intensity as the asymptotic limit. Vertical profiles of both mean concentration and fluctuation variance become well mixed downstream. Dissipation and correlation scales increase nearly in proportion to the plume width, so that time- and space-averaging the concentration is less effective in reducing the fluctuations further downstream. Concentration probability distributions show intermittency near the source but become nearly normal as the plume moves downstream. Results are compared and contrasted with the neutral flow study of Sykes and Henn (1992a, Atmospheric Environment26A, 3127–3144). |
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