| 摘要: |
| 颗粒污染物（如PM10等）在暴露体附近壁面的流动很普遍，与背景流场作用和运动归宿较复杂，且具较大研究和实用意义。本文采用近壁面湍流模型对典型直管边界层颗粒流进行模拟，研究直管湍流中颗粒沉积等特性。研究发现：在本模拟条件下，采用增强壁面模型所得流动与前人DNS结果较吻合，所得颗粒无量纲沉积速度在前人研究结果区间内。无量纲沉积速度随无量纲松弛时间增大而增大，但略有不同。在无量纲松弛时间较小且壁摩擦速度较小时，近壁面模型影响较大。当颗粒数St>1时，通过率随St增加而减小，随摩擦速度增大而增大；当St较小时不受影响。本研究初步给出不同近壁面湍流模型对暴露体附近湍流和颗粒流动的影响，有利于颗粒污染物的暴露研究和控制。 |
| 关键词: 雾霾气溶胶 近壁湍流态 颗粒踪迹去向 沉积和通过 近壁面模型 |
| DOI：10.7515/JEE201706009 |
| 分类号: |
| 基金项目:国家自然科学基金项目（11602179） |
| 英文基金项目:National Natural Science Foundation of China (11602179) |
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| Movement of micro- & fine-particles in boundary layer and near-wall area |
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SUN Ke, WANG Rui, ZHOU Kun, HE Zhu , LIU Shaojie
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State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, China
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| Abstract: |
| Background, aim, and scope Particle contaminant (e.g. PM10 & PM2.5) flow around an exposed body is commonly existed in nature, and its interaction with background flow and its fate are complicated and valuable for further research and application. Materials and methods This paper adopts turbulent and near-wall model to numerically simulate typical boundary layer and near-wall particle flow in a straight duct, and to study the detail particle deposition and penetration process in the turbulent flow. Results Under current simulation conditions, the flow behavior based on the Reynolds Stress Model and Enhanced near-wall model agrees well with previous Direct Numerical Simulation (DNS) results, while predictions from other near-wall models show partial agreements and partial discrepancies. The obtained dimensionless particle deposition velocities (DPDVs) based on these two models are generally among the range areas of literature experiment and DNS results, although differences exist. Discussion DPDVs increase with dimensionless particle relaxation times (DPRTs) increase between 4.2×10−3 < τp+ < 6.8×102, but the increasing trend is slightly different from literature data trends. The above phenomena may be attributed to different simulation and experimental conditions for different literature works. When the DPRT τp+ <1.9×10−2 and the near-wall frictional velocity u*≤19 cm ∙ s−1, the effects of different near-wall models are obvious; while above these DPRT and frictional velocity values, the near-wall models impose slightly on DPDV. Under St>1 condition, the particle penetration decreases with St increase and it increase with u* increase. Under St <1 condition, the St number has no influence on the penetration. Conclusions In short, this investigation preliminarily gives the effects of different near-wall models on nearby turbulence and particle flow of an exposed body, and this research also obtains the characteristics of particle flow fate. Recommendations and perspectives Further studies are recommended to be conduct on the interacting and modeling among turbulence, near-wall boundary layer and particle flow. These studies are believed to be useful for exposure research and effective control of particle contaminant. |
| Key words: mist / fog aerosol near wall turbulence particle trace & fate deposition & penetration near wall model |
