Modeling stratified environmental flows

由于温度、盐度和/或沉积物浓度的变化，我国大部分内陆和沿海沃茨都有密度分层。 这种密度分层现象阻碍了热量、氧气、营养盐和污染物的垂直迁移，从而对水生系统水质的理解和模拟提出了巨大的挑战。 这项研究的长远目标，是加深对密度分层水流的输送过程和混合机制的了解，以及发展电脑模式，以预测和管理本港内陆和沿岸沃茨的水质。本研究的短期目标是：（1）寻求更好地理解底坡分层流的混合机制，并量化界面混合量;（2）研究一种经济的水库放水水质管理方法，以保护下游渔业;（3）模拟气水分层流界面处的空气夹带，研究了与分层流有关的几个实际问题，包括分层池中气泡羽流和射沙脱层。在这项研究中的主要不确定性是不同密度的流体之间的混合量。 将进行实验室实验，以研究各种流动条件和分层下的混合。 流场将使用一种称为粒子图像测速的技术进行测量，混合将使用激光诱导荧光系统进行测量。实验结果将用于开发工程使用的配方，并校准和验证计算流体动力学模型，该模型将用于优化我们的水生系统的管理。

Most of our inland and coastal waters are density stratified as a result of variations in temperature, salinity and/or sediment concentration.  This density stratification prohibits the vertical transport of heat, oxygen, nutrients and pollutants, thus poses a great challenge to the understanding and modeling of water quality of aquatic systems.  The long-term objective of this study is to seek a better understanding of the transport processes and mixing mechanisms of density-stratified flows, and to develop computer models for prediction and management of the quality of our inland and coastal waters. The short-term objectives of this study are (1) to seek a better understanding of the mixing mechanisms in stratified flows over a bottom slope and to quantify the amount of the interfacial mixing, (2) to study an economical way of managing the water quality of reservoir release for protecting downstream fishery, (3) to model air entrainment at the interface of air-water stratified flows, and to study a few practically important problems related to stratified flows, including de-stratification using bubble plumes and sand jet in stratified ponds. The major uncertainty in this study is the amount of the mixing between the fluids of different densities.  Laboratory experimentation will be conducted to study the mixing under various flow conditions and stratifications.  Flow fields will be measured using a technique called particle-image-velocimetry and mixing will be measured using a laser-induced-fluorescence system. Experimental results will be used to develop formulations for engineering use, and to calibrate and validate computational fluid dynamics models which will be used to optimize the management of our aquatic systems.