CAREER: Particle dynamics at the free surface: waves, turbulence, and microplastics

职业：自由表面的粒子动力学：波浪、湍流和微塑料

• 批准号: 2237550
• 负责人: Michelle DiBenedetto
• 金额: $ 56.81万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-02-01 至 2028-01-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2237550&HistoricalAwards=false
• 关键词: CAREER; Particle; dynamics; free; surface

Plastic pollution is a ubiquitous issue impacting the health of marine ecosystems worldwide. Yet, critical knowledge gaps surrounding the fate and transport of plastic once it enters the ocean impede remediation and prevention efforts. Predicting transport is difficult for any particle in the ocean, but microplastics present a particular challenge because their size and density fall outside the regimes of traditionally studied environmental particles such as low-density bubbles and high-density sediment. Thus, the goal of this award is to (1) observe plastic particles in realistic ocean flows recreated in a controlled laboratory setting, and (2) use the observations to build a modelling framework that describes the vertical mixing and transport of plastic at the ocean surface. By examining fundamental interactions between particles and ocean flows, this award will enable more accurate modelling of buoyant particles at the ocean surface. The investigator will partner with local beach-cleanup organizations to share this work through outreach events. This award will additionally support educational activities for both undergraduate and graduate students.The ocean surface boundary layer is a multiphase flow forced by the overlying wind, which generates waves and turbulence. These processes affect the transport and mixing of materials ranging from nutrients and pollutants to bubbles and organisms. Microplastics are a new environmental particle that is increasing in concentration at the ocean surface; yet, predicting the behavior of microplastics is non-trivial because it depends on poorly understood interactions among waves, turbulence, and particle inertia in the ocean surface boundary layer (where most microplastics reside). To help close this foundational knowledge gap in particle-laden flows and improve microplastics transport modeling, this award seeks to describe how the rise velocity of buoyant particles is modulated by the combined effects of waves and turbulence, the processes by which particles are entrained beneath the surface, and the controls on particle diffusivity in waves and turbulence. The research will be conducted in a laboratory facility that can generate both wind and waves. Advanced optical techniques will be used to track particles both at the surface and beneath it under a range of surface conditions, including breaking waves. These observations will be used to develop a wave phase-resolved model for the transport and mixing of buoyant particles in a free-surface boundary layer, a model which will be broadly applicable to microplastics, and other particles found at the ocean surface.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.

塑料污染是一个无处不在的问题，影响了全球海洋生态系统的健康。然而，一旦塑料进入海洋，围绕塑料的命运和运输的关键知识差距阻碍了修复和预防工作。对于海洋中的任何粒子来说，都难以预测运输，但是微塑料会带来一个特殊的挑战，因为它们的大小和密度不在传统研究的环境颗粒（例如低密度气泡和高密度沉积物）的状态之外。因此，该奖项的目的是（1）在受控实验室环境中重新创建的逼真的海洋流中的塑料颗粒，以及（2）使用观测值来构建一个建模框架，描述了塑料在海面上的垂直混合和运输。通过检查颗粒与海洋流之间的基本相互作用，该奖项将使海洋表面上的浮力颗粒更准确地建模。调查人员将与当地的海滩清洗组织合作，通过外展活动分享这项工作。该奖项还将支持本科和研究生的教育活动。海面边界层是由上覆的风引起的多相流，它产生了波浪和湍流。这些过程会影响从营养和污染物到气泡和生物的材料的运输和混合。微塑料是一种新的环境粒子，在海面的浓度正在增加。然而，预测微塑料的行为是非平凡的，因为它取决于海面边界层中波，湍流和粒子惯性之间的相互作用较低（大多数微塑料都位于其中）。为了帮助缩小颗粒充满粒子流的基础知识差距并改善微塑料传输建模，该奖项旨在描述如何通过波和湍流的组合作用来调节浮力颗粒的上升速度，以及颗粒在表面下方夹带的过程以及对波和涡轮构粒粒子膨胀率的过程。该研究将在可以产生风和波浪的实验室设施中进行。先进的光学技术将用于在表面条件范围内（包括断裂波）在表面和下方跟踪颗粒。 These observations will be used to develop a wave phase-resolved model for the transport and mixing of buoyant particles in a free-surface boundary layer, a model which will be broadly applicable to microplastics, and other particles found at the ocean surface.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.