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Modeling the effect of saltation on surface layer turbulence
Earth Surface Processes and Landforms ( IF 2.8 ) Pub Date : 2020-10-06 , DOI: 10.1002/esp.5013 Hao‐Jie Huang 1
Earth Surface Processes and Landforms ( IF 2.8 ) Pub Date : 2020-10-06 , DOI: 10.1002/esp.5013 Hao‐Jie Huang 1
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Particle–turbulence interaction has been a research focus in the field of pneumatic transport, especially in aeolian environments. However, knowledge regarding the effect of saltating particles on the turbulence characteristics is very limited. In this article, a process of sand‐laden flow from forming sand streamers to stability is investigated via a coupled mathematical model of wind‐blown sand that includes the spatiotemporal development. The variations in the turbulence characteristics, such as the mean velocity and turbulence intensity in clean air or sand‐laden flow field, are analyzed. The results show that the splash process of sand grains near the wall decrease the wind speed in the saltation layer and destroy the low‐speed streaks. Moreover, the profiles of streamwise turbulence intensity exhibit a transition from ‘decreasing’ to ‘increasing’ and approximately intersect at an ‘intensity focus’, which is presented for the first time. Furthermore, it was found that saltating particles could enhance the Reynolds stress. Meanwhile, it was also noticed that the shear stress at the wall surface is greater than the impact threshold and that there is a tendency towards the impact threshold. Therefore, saltation makes the particle Reynolds number of sand‐laden flow higher than that under non‐saltation conditions, thus changing the particles’ effect on the turbulence intensity. Gravity‐dominated saltation is probably the most essential difference between wind‐blown sand and other traditional two‐phase flows. © 2020 John Wiley & Sons, Ltd.
中文翻译：
模拟盐析对表层湍流的影响
颗粒-湍流相互作用一直是气动运输领域的研究重点，特别是在风环境中。然而，关于盐化颗粒对湍流特性的影响的知识非常有限。在本文中，通过包含时空发展的风沙耦合数学模型，研究了从形成砂带到稳定的含沙流过程。分析了湍流特性的变化，例如清洁空气或含沙流场中的平均速度和湍流强度。结果表明，壁附近的沙粒飞溅过程降低了盐分层的风速并破坏了低速条纹。此外，湍流强度分布呈现出从“减小”到“增加”的过渡，并且在“强度焦点”处近似相交，这是首次出现。此外，发现盐化颗粒可以增强雷诺应力。同时，还注意到壁表面处的剪切应力大于冲击阈值，并且存在朝向冲击阈值的趋势。因此，盐化使含沙流的颗粒雷诺数高于非盐化条件下的雷诺数，从而改变了颗粒对湍流强度的影响。重力主导的盐分可能是风沙和其他传统两相流之间最根本的区别。分级为4 +©2020 John Wiley＆Sons，Ltd.
更新日期：2020-12-14
中文翻译：
模拟盐析对表层湍流的影响
颗粒-湍流相互作用一直是气动运输领域的研究重点，特别是在风环境中。然而，关于盐化颗粒对湍流特性的影响的知识非常有限。在本文中，通过包含时空发展的风沙耦合数学模型，研究了从形成砂带到稳定的含沙流过程。分析了湍流特性的变化，例如清洁空气或含沙流场中的平均速度和湍流强度。结果表明，壁附近的沙粒飞溅过程降低了盐分层的风速并破坏了低速条纹。此外，湍流强度分布呈现出从“减小”到“增加”的过渡，并且在“强度焦点”处近似相交，这是首次出现。此外，发现盐化颗粒可以增强雷诺应力。同时，还注意到壁表面处的剪切应力大于冲击阈值，并且存在朝向冲击阈值的趋势。因此，盐化使含沙流的颗粒雷诺数高于非盐化条件下的雷诺数，从而改变了颗粒对湍流强度的影响。重力主导的盐分可能是风沙和其他传统两相流之间最根本的区别。分级为4 +©2020 John Wiley＆Sons，Ltd.
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