Spray generation by collective bubble bursting

海洋中的气泡是在破碎的波浪将空气带入海面下后形成的。气泡破裂产生的浪花通过输送水、热、溶解气体、盐、表面活性剂和生物材料来影响海洋和大气之间的交换，是天气预报和飓风增强的主要参与者。尽管进行了长期的努力，但海喷产量预测仍然存在很大的不确定性；这是由于缺乏对海沫滴大小和速度的原始分布的了解。研究将跨越与问题相关的所有尺度，从单个气泡到海洋表面的波浪统计；它将包括在单一实验和数值框架内对关键变量（如表面活性剂浓度、温度、湍流）的影响进行详细研究。更好地了解和改进海雾产生的参数化对于改善海洋-大气之间的热、湿和气溶胶交换，以及气候和天气模式和预报的关键要素是必要的。海洋喷雾气溶胶是云凝结核，更好地了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。浪花还与沿海环境中的健康问题有关。当赤潮出现时，比如墨西哥湾，大量有害藻类释放出毒素，这些毒素可以以气溶胶的形式传播到城市社区。本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升级方法是通用的，也可用于改进其他海洋-大气相互作用的建模。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。该项目还将通过研讨会和教学活动促进开源方法的使用。复杂的集体破裂液滴形成过程取决于多个变量：湍流上层海洋中气泡的大小和密度、表面的聚结和泡沫形成以及水的物理化学性质。该项目将通过开展一项综合研究，将高质量的实验室数据和数值数据结合起来，建立海沫滴大小和速度分布的模型，填补我们在知识方面的空白。单泡沫破裂将研究与国家的最先进的数值模拟，发展在泡沫规模的基本认识。通过室内实验研究了矿化度、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，将采用一种升级方法，通过整合破碎统计数据的结果，从单个破碎波携带的气泡羽流到海洋尺度，从而使数值模式更好地参数化海浪通量。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。

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.