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首页> 外文会议>25th Conference on Agricultural and Forest Meteorology and 12th Joint Conference on the Applications of Air Pollution Meteorology with Aamp;WMA and Fourth Symposium on the Urban Environment May 20-24, 2002 Norfolk, Virginia >LAGRANGIAN PARTICLE MODELING OF BUOYANT PLUME DISPERSION IN THE CONVECTIVE BOUNDARY LAYER
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LAGRANGIAN PARTICLE MODELING OF BUOYANT PLUME DISPERSION IN THE CONVECTIVE BOUNDARY LAYER

机译：对流边界层中浮体羽流的拉格朗日粒子建模。

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摘要

Dispersion of buoyant plumes from tall stacks is usually most rapid in a convective boundary layer (CBL) due to the mixing by the large convective eddies. Such mixing often leads to the highest ground-level concentrations (GLCs) of stack effluents over short averaging times (≤ 1 hr). For highly buoyant plumes, the maximum GLCs are found during lofting followed by downward mixing, i.e., when the plume rises to the CBL top, is trapped there by the elevated inversion capping the boundary layer, and then disperses downwards. Laboratory experiments show that the dimensionless buoyancy flux F_* is the most important parameter characterizing the relative effects of buoyancy and ambient convection (Willis and Deardorff, 1987). The F_* is given by F_* = F_b/(U w_*~2 z_i), where F_b is the source buoyancy flux, U is the mean wind speed over the CBL, w_* is the convective velocity scale, and z_i is the CBL depth. The source buoyancy can be divided roughly into three ranges based on the plume behavior: low buoyancy for F_* ≤ 0.05 where the plume behaves similarly to that for a non-buoyant release; moderate buoyancy for 0.05 ≤ F_* ≤ 0.1; and high buoyancy for F_* > 0.1, corresponding to plume lofting. Modeling of the high buoyancy case has been the most problematic. This paper presents a Lagrangian particle model for buoyant releases in the CBL with focus on the lofting situation; however, all buoyancy ranges are addressed.
机译：由于对流边界层的混合，通常在对流边界层（CBL）中从高烟囱中散发出的浮羽通常最快。这种混合通常会在较短的平均时间（≤1小时）内导致烟囱流出物的最高地面浓度（GLC）。对于高度浮力的羽流，在放样过程中发现最大的GLC，然后向下混合，即，当羽流升至CBL顶部时，被边界层上方升高的反转圈住而被困在那里，然后向下扩散。实验室实验表明，无因次浮力通量F_ *是表征浮力和环境对流相对影响的最重要参数（Willis和Deardorff，1987）。 F_ *由F_ * = F_b /（U w_ *〜2 z_i）给出，其中F_b是源浮力通量，U是CBL上的平均风速，w_ *是对流速度标度，z_i是CBL深度。根据羽流行为，源浮力大致可分为三个范围：F_ *≤0.05时的低浮力，其中羽流的行为与非浮力释放类似。 0.05≤F_ *≤0.1的中等浮力; F_ *> 0.1时具有高浮力，对应于羽状放样。高浮力情况的建模是最成问题的。本文介绍了拉格朗日粒子模型的CBL中浮力释放，着重于放样情况。但是，所有浮力范围都可以解决。

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