Experimental environmental hydraulics: entrainment and mixing in turbulent flows

实验环境水力学：湍流中的夹带和混合

• 批准号: 203125-2011
• 负责人: Gaskin, Susan
• 金额: $ 1.38万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2012
• 资助国家: 加拿大
• 起止时间: 2012-01-01 至 2013-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=508913
• 关键词: Experimental; environmental; hydraulics; entrainment; mixing

The increasingly stringent environmental laws on pollution motivate the study of environmental hydraulics. Its concern is with the disposal and accidental spills of effluents to the atmosphere and to surface water bodies like rivers, lakes and oceans, and the prediction of the effluents' subsequent dispersion at the local or regional scale (up to 100 km). Turbulent mixing and, hence, dilution minimizes or mitigates the detrimental effects. One of the remarkable properties of turbulence is its capacity to mix and dilute either a vector (effluent velocity) or a scalar (pollutant) extremely rapidly. Prediction or analysis of pollutant dispersion in turbulent flows (effluent and/or receiving water body) gives rise to engineering problems for which an understanding of turbulent mixing processes is required. The long term research objective is a deeper understanding of turbulent transport and mixing processes, while the short term goals are to investigate the following four topics. 1) The effect of ambient turbulence on jet dynamics and the entrainment mechanisms will be studied using 3-D particle tracking velocimetry (PTV) experiments. Recent work indicating that turbulence in the ambient reduces dilution rates, contrary to the prevailing assumption, will be extended to examine changing entrainment mechanisms. 2) The suppressed mixing mechanisms at river confluences will be studied experimentally using PTV and statistical analysis of the turbulence and will use geomorphological and geographical experience to interpret the results for real environments. 3) Lagrangian flow statistics in isotropic homogeneous turbulence will be determined experimentally using 3-D PTV in an approximately isotropic homogeneous turbulent flow created using a random jet array. The results will improve turbulent dispersion models of environmental flows. 4) SPH-ALE modeling of free surface channel flows with sediment transport will use the mesh-free Lagrangian particle method, SPH, which is suited to problems with deformable boundaries, moving interfaces and large deformations. The ALE adaptation of SPH is more computationally efficient and improves the treatment of the boundary conditions which is important for free surface river flows with sediment transport.

日益严格的环境污染法规推动了环境水力学的研究。 它所关注的是排放物的处置和意外泄漏到大气层和河流、湖泊和海洋等地表水体中，以及预测排放物随后在地方或区域范围内（最远100公里）的扩散。湍流混合以及由此产生的稀释最小化或减轻了有害影响。湍流的一个显著特性是它能够非常迅速地混合和稀释矢量（流出速度）或标量（污染物）。预测或分析污染物在湍流（流出物和/或接收水体）中的扩散会引起工程问题，需要了解湍流混合过程。长期研究目标是加深对湍流输送和混合过程的理解，而短期目标是研究以下四个主题。1)环境湍流对射流动力学和卷吸机制的影响将使用3-D粒子跟踪测速（PTV）实验进行研究。最近的工作表明，在环境中的湍流降低稀释率，与流行的假设相反，将扩展到检查不断变化的夹带机制。 2)将使用PTV和湍流的统计分析对河流汇合处的抑制混合机制进行实验研究，并将使用地貌和地理经验来解释真实的环境的结果。3)各向同性均匀湍流中的拉格朗日流统计将通过实验确定，使用3-D PTV在近似各向同性均匀湍流中使用随机射流阵列创建。研究结果将有助于改进环境流的湍流扩散模型。4)考虑泥沙输移的自由面河道水流的SPH-ALE模拟将使用无网格拉格朗日粒子法SPH，该方法适用于具有可变形边界、移动界面和大变形的问题。ALE适应SPH是更有效的计算，并改善了边界条件的处理，这是重要的自由表面河流水流泥沙输移。