Experimental Environmental Hydraulics: Turbulent Entrainment and Mixing

水不仅对生命和环境至关重要，而且对社会使用的有效基础设施也是必不可少的。在环境水力学和水资源工程学中，研究和开发了人类对水的利用及其对地表水资源(湖泊、河流、海洋)的影响的解决方案。这项建议涉及三个问题：i)改进地表水污染物扩散模型；ii)粘性沉积物的河流侵蚀预测；iii)评价和处理饮用水中的金属污染。对于污染物在水圈中扩散的应用问题，需要了解湍流混合的基本流体动力学。本文考虑了当前离散模型高估稀释的两种情况。首先，携带污染物的动量射流被释放为湖泊、河流和海洋中的湍流，但目前对扩散的模拟是基于权宜之计的假设，即湍流扩散造成的稀释可以添加到射流驱动的稀释中。最近的研究表明，在这种情况下，稀释度实际上是减少的，这激发了一项关于湍流环境中喷流卷吸变化的基础研究。其次，河流汇合处下游的混合可能导致两条溪流并排流动，最长可达100公里。我们将研究同向流动之间混合层的流体力学，以了解并预测在这些浅层流动中发生的横向混合减少。在水资源工程方面，河流工程师在粘性沉积物(粘土和碎屑)中发现了意想不到的河岸侵蚀，这是由于城市化导致的河流流量更高、变化更大，以及气候变化导致的更高强度的降水事件造成的。由于河流侵蚀机制和阈值随沉积物的性质和沉积历史而变化，将进行实地调查，在五大湖和圣劳伦斯低地采集具有代表性的粘性沉积物样品。样品将接受河流侵蚀试验，岩土试验将确定沉积物的特征，以便对各种行为进行分类，以便更好地预测侵蚀风险。必须提供足够数量和足够质量的饮用水，以确保公众健康。饮用水中的金属污染是一个令人担忧的问题，因为它具有神经毒性作用。虽然砷的神经毒性是众所周知的，但铜虽然是一种微量营养素，但最近被认为与阿尔茨海默病有关。这促使开发了一种使用废壳作为活性成分的廉价使用点处理方法来处理水中的砷，并调查了饮用水中铜的暴露情况，并详细审查了饮用水准则。

Water is not only essential for life and the environment, but also for a functioning infrastructure for society's use. Solutions for the anthropogenic use of water and its impact on surface water resources (lakes, rivers, oceans) are investigated and developed in environmental hydraulics and in water resources engineering. Three problems are addressed in this proposal i) improving pollutant dispersion modelling in surface water, ii) prediction of fluvial erosion of cohesive sediments and iii) assessing and treating metal contamination of drinking water. For applied problems of pollutant dispersion in the hydrosphere, an understanding of the fundamental fluid dynamics of turbulent mixing is required. Two cases in which current dispersion models overestimate dilution are considered. Firstly, momentum jets carrying pollutants are released into turbulent flows in lakes, rivers and oceans, yet the dispersion is currently modelled based on the expedient assumption that the dilution due to turbulent diffusion can be added to the jet driven dilution. Recently it has been shown that, in fact, dilution is reduced in this case, motivating a fundamental study of the change in entrainment for a jet in a turbulent ambient. Second, the mixing downstream of river confluences can result in two streams flowing side by side for up to a hundred kilometers. The fluid mechanics of the mixing layer between the coflowing streams will be studied to understand, and then predict, the reduced transverse mixing occurring in these shallow flows. In water resources engineering, river engineers are finding unexpected river bank erosion in cohesive sediments (clays and tills) caused by higher and more variable river flows occurring due to urbanisation and higher intensity precipitation events due to climate change. As the fluvial erosion mechanisms and thresholds vary as a function of the character and depositional history of the sediment, a field survey will be undertaken to sample a representative number of cohesive sediment samples in the Great Lakes and St. Lawrence Lowlands. The samples will be subject to fluvial erosion tests and geotechnical tests will characterize the sediments allowing the range of behaviours to be classified in order to better predict erosion risk. The provision of an adequate quantity and an adequate quality of drinking water is required to ensure public health. Metal contamination of drinking water is a concern due to it neurotoxicant effect. While the neuro-toxicity of arsenic is well known, copper, although a micronutrient, has recently been linked to Alzheimer's disease. This motivates the development of a cheap point-of-use treatment for arsenic in water using waste shells as the active ingredient, and an investigation of exposure to copper from drinking water and a detailed review of drinking water guidelines.