流量变化对常规街道网络中连续排放和喷涌排放的扩散的影响

IF 2.3 3区 地球科学 Q3 METEOROLOGY & ATMOSPHERIC SCIENCES
T. Auerswald, K. Klippel, T. G. Thomas, E. V. Goulart, M. Carpentieri, P. Hayden, D. Hertwig, N. C. Reis, A. Robins, O. Coceal
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引用次数: 0

摘要

本研究通过直接数值模拟(DNS),并与风洞(WT)测量结果进行比较,研究了不同尺度的流动变化及其对规则街道网络中被动标量的扩散的影响。解决的具体科学问题包括(i) 街道网络尺度上流动的变异性来源,(ii) 这种变异性对瞬时和连续局部释放的影响,(iii) 与实验设置有关的其他不确定性来源及其后果。这里模拟的街道网络由均匀排列的矩形建筑物阵列组成,具有周期性水平边界条件。气流由与网络中的街道成 45 度角的体力驱动。被动标量源位于地面附近的三种不同位置:短街道、街道之间的交叉口和长街道。记录了不同尺度的水流变化:与当地水流拓扑结构相关的小尺度街道内变化;街道间水流结构差异;街道-网络尺度变化;以及与树冠上方结构相关的更大尺度空间变化。分析了街道网络中被动标量连续释放和短时间(喷发)释放的流量统计和扩散行为,并与风洞测量结果进行了比较。结果与十字路口源位置的实验数据非常吻合,特别是连续释放的流量统计和平均浓度曲线。较大的差异出现在对脉冲释放的比较中。这些差异是通过计算若干粉尘参数(包括到达时间、传播时间、上升和衰减时间)来量化的。讨论了造成差异的原因,包括已确定的基本流动变异性、DNS 和 WT 设置之间的差异以及实验设置中的不确定性。根据我们的研究结果,讨论了短时释放在实际城市地区传播的影响。特别强调的是,在模拟意外排放等奇异事件时,描述不确定性比计算集合平均值更有意义、更有用。
本文章由计算机程序翻译,如有差异,请以英文原文为准。

Effect of Flow Variability on Dispersion of Continuous and Puff Releases in a Regular Street Network

Effect of Flow Variability on Dispersion of Continuous and Puff Releases in a Regular Street Network

This study investigates flow variability at different scales and its effects on the dispersion of a passive scalar in a regular street network by means of direct numerical simulations (DNS), and compared to wind tunnel (WT) measurements. Specific scientific questions addressed include: (i) sources of variability in the flow at street-network scale, (ii) the effects of such variability on both puff and continuous localised releases, (iii) additional sources of uncertainty related to experimental setups and their consequences. The street network modelled here consists of an array of rectangular buildings arranged uniformly and with periodic horizontal boundary conditions. The flow is driven by a body force at an angle of 45 degrees relative to the streets in the network. Sources of passive scalars were located near ground level at three different types of locations: a short street, an intersection between streets and a long street. Flow variability is documented at different scales: small-scale intra-street variations linked with local flow topology; inter-street flow structure differences; street-network scale variability; and larger-scale spatial variations associated with above-canopy structures. Flow statistics and the dispersion behaviour of both continuous and short-duration (puff) releases of a passive scalar in the street network are analysed and compared with the results of wind-tunnel measurements. Results agree well with the experimental data for a source location in an intersection, especially for flow statistics and mean concentration profiles for continuous releases. Larger differences arise in the comparisons of puff releases. These differences are quantified by computing several puff parameters including time of arrival, travel time, rise and decay times. Reasons for the differences are discussed in relation to the underlying flow variability identified, differences between the DNS and WT setup and uncertainties in the experimental setup. Implications for the propagation of short-duration releases in real urban areas are discussed in the light of our findings. In particular, it is highlighted that in modelling singular events such as accidental releases, characterising uncertainties is more meaningful and useful than computing ensemble averages.

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来源期刊
Boundary-Layer Meteorology
Boundary-Layer Meteorology 地学-气象与大气科学
CiteScore
7.50
自引率
14.00%
发文量
72
审稿时长
12 months
期刊介绍: Boundary-Layer Meteorology offers several publishing options: Research Letters, Research Articles, and Notes and Comments. The Research Letters section is designed to allow quick dissemination of new scientific findings, with an initial review period of no longer than one month. The Research Articles section offers traditional scientific papers that present results and interpretations based on substantial research studies or critical reviews of ongoing research. The Notes and Comments section comprises occasional notes and comments on specific topics with no requirement for rapid publication. Research Letters are limited in size to five journal pages, including no more than three figures, and cannot contain supplementary online material; Research Articles are generally fifteen to twenty pages in length with no more than fifteen figures; Notes and Comments are limited to ten journal pages and five figures. Authors submitting Research Letters should include within their cover letter an explanation of the need for rapid publication. More information regarding all publication formats can be found in the recent Editorial ‘Introducing Research Letters to Boundary-Layer Meteorology’.
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