Spray generation by collective bubble bursting

海洋中的气泡是在破碎的海浪将空气带到海面以下后形成的。气泡破裂产生的海雾水滴通过输送水、热、溶解气体、盐类、表面活性剂和生物材料来影响海洋和大气之间的交换，是天气预报和飓风加强的主要参与者。尽管进行了长期的努力，但海雾产量预测仍然存在很大的不确定性；这是由于缺乏对海雾水滴大小和速度的原始分布的了解。这项研究将跨越与这一问题有关的所有尺度，从单个气泡到海洋表面的波浪统计；它将包括在单一的实验和数值框架内详细研究关键变量的影响，如表面活性剂的浓度、温度、湍流。有必要更好地了解和改进海洋喷雾生产的参数，以改善海洋-大气之间的热量、水分和气溶胶的交换，以及气候和天气模型和预报的关键要素。海雾气溶胶作为云的凝结核，更好地理解云的产生和增长被许多人视为气候科学中最大的挑战之一。海雾还与沿海环境中的健康问题有关。当赤潮出现时，例如墨西哥湾，有害藻类的大量繁殖会释放出毒素，这些毒素可以气雾剂的形式传播到城市社区。这项研究中使用的将小尺度、详细过程与更大尺度的海洋联系起来的提升尺度方法是通用的，也可以用来改进其他海洋-大气相互作用的模拟。通过这个项目，普林斯顿大学的本科生和研究生将接触到关键的环境挑战，这些挑战需要研究基本的多相流。该项目还将通过讲习班和教学活动促进开源方法的使用。集体爆发形成复杂的水滴过程取决于多个变量：在湍急的上层海洋中上升的气泡的大小和密度、表面的聚结和泡沫形成以及水的物理化学性质。该项目将通过进行一项综合研究来填补我们知识的空白，该研究综合了高质量的实验室数据和数值数据，以建立海雾水滴大小和速度分布的模型。我们将用最先进的数值模拟技术来研究单个气泡的破裂，加深对气泡尺度的基本理解。将通过实验室实验研究盐度、温度和表面活性剂等物理和化学变量对集体气泡破裂、泡沫老化和液滴形成的影响。最后，将采用一种提升尺度的方法，通过整合破裂统计的结果，从单个破碎波携带的气泡羽流到海洋尺度，导致数值模式的海雾通量更好地参数化。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Bubbles in the ocean are formed after a breaking wave has entrained air below the sea surface. Sea spray drops created by bubble bursting affect the exchange between the ocean and atmosphere by transporting water, heat, dissolved gases, salts, surfactants, and biological materials, and are major players in weather prediction and hurricane intensification. Large uncertainties in sea spray production predictions remain despite long standing efforts; this is attributed to the lack of knowledge in the original distribution of sea spray drop sizes and velocities. The research will span all scales relevant to the problem, from individual bubbles to wave statistics at the ocean surface; it will include detailed studies of the impact of key variables such as the concentration of surfactants, temperature, turbulence within a single experimental and numerical framework. A better understanding and improved parameterizations of sea spray production are necessary to improve the exchange between ocean-atmosphere of heat, moisture and aerosols, key elements of climate and weather models and forecast. Sea spray aerosols serve as cloud condensation nuclei and a better understanding of clouds generation and growth is seen by many as one of the biggest challenges in climate sciences. Sea spray is also related to health issues in coastal environments. When red tides are present, such as the Gulf of Mexico, blooms of harmful algae release toxins that can be transported as aerosols up to urban communities. The upscaling approach used in this study to connect the small scale, detailed processes to the larger scales of the ocean is general and could be used to improve the modeling of other ocean-atmosphere interactions as well. Through this project, undergraduate and graduate students at Princeton will be exposed to critical environmental challenges that require research on fundamental multi-phase flows. The project will also promote the use of open source methods through workshops and teaching activities.The complex droplet formation process by collective bursting depends on multiple variables: the size and density of the bubbles rising in the turbulent upper ocean, the coalescence and foam formation at the surface and the physical-chemical properties of water. This project will fill gaps in our knowledge by conducting a comprehensive study that integrates high quality laboratory and numerical data to build models for the distribution of sizes and velocities of sea spray drops. Single bubble bursting will be studied with state of the art numerical simulations, developing a fundamental understanding at the bubble scale. The role physical and chemical variables, such as salinity, temperature and surfactant on the collective bubble bursting, foam aging and droplet formation will be investigated with laboratory experiments. Finally, an upscaling approach will be employed, going from one bubble plume entrained by a single breaking wave to the ocean scale by integrating the results over the breaking statistics, leading to a better parameterization of sea spray fluxes for numerical models.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.