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，因为它需要对控制飓风运动的复杂多尺度现象有深入的了解。过去的研究表明，海洋喷雾对飓风动力学的影响很大程度上取决于喷雾液滴的大小。因此，PI将重点发展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员伤亡。该研究项目还将允许北卡罗来纳州a&t州立大学（一个国家支持的HBCU）维持和扩大最近在应用数学和科学计算方面建立的新研究和教育能力，并将其应用于大气多相湍流。具体来说，PI将通过精确计算浪花的多分散性来扩展目前存在的飓风边界层的数学模型。所建立的模式将用于在大风飓风条件下对海洋大气边界层动力学的影响进行全面的参数化研究。为了填补目前在理解喷雾多分散性影响方面的空白，PI计划采用湍流分散多相流的现代理论和欧拉多流体方法。这种方法将不同大小的液滴、空气和水蒸气视为单独的相互作用的湍流连续体，每个连续体都有自己的一套守恒定律，并以自己的速度、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裂/聚结和蒸发/冷凝动力学。将该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。该奖项反映了美国国家科学基金会的法定使命，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.