Experimental Environmental Hydraulics: Turbulent Entrainment and Mixing

水不仅对生命和环境至关重要，而且对社会使用的功能基础设施也是必不可少的。在环境水力学和水资源工程中，研究和开发了人为用水及其对地表水资源（湖泊、河流、海洋）的影响的解决方案。本提案解决了三个问题：1)改进地表水中的污染物扩散模型；2)预测粘性沉积物的河流侵蚀；3)评估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。考虑了当前分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到湖泊、河流和海洋的湍流中，但目前对弥散的建模基于一种权宜的假设，即湍流扩散引起的稀释可以加入射流驱动的稀释。最近有研究表明，在这种情况下，稀释实际上减少了，这激发了对湍流环境中射流夹带变化的基础研究。其次，河流汇合处下游的混合可以导致两条河流并排流动长达100公里。将研究共流流之间混合层的流体力学，以了解并预测这些浅流中发生的减少横向混合。在水资源工程中，河流工程师发现，由于城市化和气候变化导致的高强度降水事件，河流流量的增加和变化，导致粘性沉积物（粘土和坡地）发生了意想不到的河岸侵蚀。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，因此将对五大湖和圣劳伦斯低地具有代表性的粘性沉积物样本进行实地调查。这些样品将接受河流侵蚀测试，岩土技术测试将对沉积物进行表征，从而对其行为范围进行分类，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。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，最近却与阿尔茨海默病有关。这促使开发一种廉价的使用点处理方法，利用废贝壳作为有效成分处理水中的砷，并调查从饮用水中接触铜的情况，并详细审查饮用水准则。

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.