Excellence in Research: The study of dynamics of an atmospheric boundary layer laden with polydisperse spray under high-wind conditions of a hurricane

预测飓风强度是一项非常具有挑战性的任务，因为它需要深入了解控制飓风运动的复杂多尺度现象。过去的研究表明，海洋喷雾对飓风动力学的影响强烈依赖于喷雾液滴的大小。因此，PI将专注于开发一个全面的数学框架及其数值实现，以准确模拟多分散海洋喷雾对飓风边界层中动量和热量垂直通量的影响。这将有助于提高飓风预报的准确性，从而有助于最大限度地减少财产损失和人命损失。该研究项目还将使北卡罗来纳州AT州立大学，一个国家支持的HBCU，以维持和扩大最近建立的新的研究和教育能力，在应用数学和科学计算与应用到大气多相湍流。具体来说，PI将扩大目前现有的数学模型的飓风边界层与海洋喷雾准确占喷雾多分散性。将利用所开发的模式进行一项综合参数研究，以了解其对强风飓风条件下海洋大气边界层动态的影响。为了填补目前在理解喷雾多分散性影响方面的空白，PI计划采用现代湍流分散多相流理论和欧拉多流体方法。这种方法将不同大小的液滴、空气和水蒸气视为独立的相互作用的湍流连续体，每个连续体由其自身的一组守恒定律描述，并以其自身的速度、温度和湍流动能分布为特征。多分散喷雾的守恒定律将以种群平衡方程的形式给出。特别是，该方法将始终考虑液滴破碎/聚结和蒸发/冷凝动力学。 将这种方法与高阶多流体湍流模型相结合，将使PI能够准确预测多分散海洋喷雾对飓风动力学和结构的影响。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Predicting hurricane intensity is a very challenging task because it requires an in-depth understanding of complex multi-scale phenomena governing hurricane motion. Past research has demonstrated that the ocean spray effects on hurricane dynamics depend strongly on the size of spray droplets. Therefore, the PI will focus on developing a comprehensive mathematical framework and its numerical implementation to accurately model the polydisperse ocean spray effect on the vertical fluxes of momentum and heat in a hurricane boundary layer. This will aid in improving the accuracy of hurricane forecasts, which in turn will help minimize property damage and loss of human life. The research project will also allow North Carolina A&T State University, a state-supported HBCU, to sustain and expand recently established new research and educational capacity in applied mathematics and scientific computing with applications to atmospheric multiphase turbulent flows. Specifically, the PI will expand the currently existing mathematical model of a hurricane boundary layer laden with ocean spray by accurately accounting for spray polydispersity. The developed model will be used to conduct a comprehensive parametric study of its effect on the dynamics of the marine atmospheric boundary layer in high-wind hurricane conditions. To fill the current gap in understanding spray polydispersity's influence the PI plans to employ a modern theory of turbulent disperse multiphase flows and the Eulerian multi-fluid approach. This approach considers groups of droplets of different sizes, air, and water vapor as separate interacting turbulent continua, each described by its own set of conservation laws and characterized by its own velocity, temperature, and turbulent kinetic energy distributions. The conservation laws for polydisperse spray will be presented in the form of population balance equations. In particular, the method will consistently account for droplet breaking/coalescence and evaporation/condensation dynamics. Combining this method with a higher-order multi-fluid turbulence model will enable the PI to accurately predict the influence of polydisperse ocean spray on hurricane dynamics and structure.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.