Analytical solution for scalar transport in open channel flow: Slow-decaying transient effect
Analytical solution for scalar transport in open channel flow: Slow-decaying transient effect
复制标题
明渠流中标量输运的解析解：慢衰减瞬态效应
DOI：
10.1016/j.jhydrol.2014.09.044
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发表时间：
2014-11
影响因子：
6.4
通讯作者：
Chen G. Q.
中科院分区：
文献类型：
--
作者：
Wu Zi;Chen G. Q.
众所周知，广泛应用的泰勒色散模型只能预测纵向分布的平均浓度。与此同时，环境流体流中有毒污染物迁移的风险评估应用需要有关横截面浓度分布的详细信息。最近的一些进展（Wu, Z., Chen, G.Q., 2014, J. Fluid Mech., 740, 196–213.）表明，横向浓度与平均值的偏差可以在很长一段时间内显着，这被称为慢衰减瞬态效应。因此，研究层流明渠流中标量传递的浓度演化过程非常重要。在本文中，通过两尺度扰动分析，对跨通道均匀瞬时标量释放的理想化情况进行了分析探索。通过得到的解析解讨论了平均浓度泰勒色散模型的有效性。首次对明渠流的二维浓度分布进行了分析探讨。确定了浓度演化的相应时间尺度，表明垂直浓度差减小的过程将比平均浓度变为高斯的过程慢得多。由于受所谓的慢衰减瞬态效应的影响，需要修改均匀垂直分布才能正确预测垂直浓度分布。
It is well known that the extensively applied Taylor dispersion model only predicts the longitudinally distributed mean concentration. While at the same time, applications as the risk assessment for toxic pollutant transport in environmental fluid flows require detailed information on the cross-sectional concentration distribution. As shown by some recent progress (Wu, Z., Chen, G.Q., 2014, J. Fluid Mech., 740, 196–213.), the deviation of transverse concentration from the mean can be remarkable for a very long time, which is termed as the slow-decaying transient effect. Thus it is important to examine the process of concentration evolution for scalar transport in laminar open channel flow. In this paper, the idealized case of a uniform and instantaneous scalar release across the channel is analytically explored by a two-scale perturbation analysis. The validity of the Taylor dispersion model for the mean concentration is discussed by the obtained analytical solution. For the first time, the two-dimensional concentration distribution for the open channel flow is explored analytically. Corresponding time scales for the concentration evolution are determined, indicating that the process for the vertical concentration difference to diminish will be much slower than that for the mean concentration to become Gaussian. Dominated by the so-called slow-decaying transient effect, the uniform vertical distribution needs to be modified to predict the vertical concentration distribution correctly.
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影响因子：
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作者：
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通讯作者：
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影响因子：
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作者：
C. G. Phillips;S. R. Kaye
通讯作者：
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影响因子：
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作者：
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影响因子：
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作者：
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DOI：
10.1016/j.cnsns.2012.03.002
发表时间：
2012-11
影响因子：
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作者：
L. Zeng;Guoqian Chen;Zi Wu;Z. Li;Y. Wu;P. Ji
通讯作者：
L. Zeng;Guoqian Chen;Zi Wu;Z. Li;Y. Wu;P. Ji