Spontaneous Dispersion of Particles in Liquid Surfaces

1236035Singh这项研究的目的是研究粒子吸附的物理学以及粒子与流体-流体界面接触时发生的粒子自发扩散。面粉、花粉等小颗粒的分散速度很快，看起来像是爆炸性的，尤其是在水等流动液体的表面。这种由界面力驱动的颗粒分散是很重要的，因为它会导致散布在小面积上的颗粒几乎瞬间分散成大几个数量级的区域上的单层。虽然Weber数和Bond数以及接触角是控制颗粒垂直于界面运动的重要无量纲参数，但控制颗粒横向运动的参数并不完全清楚。我们的主要目标是：(I)利用实验和直接的数值模拟来确定粒子扩散速度对重要参数的依赖关系，并量化包括微生物和病毒在内的小粒子在液体表面的扩散速度所产生的增强。(Ii)模拟水生植物二维授粉过程的流体动力学。(Iii)模拟导致液体表面凝聚体破裂和扩散的机理。过去的研究重点一直集中在了解已经被困在液-液界面上的粒子相互作用的机制。这项拟议的研究将首次考虑突然扩散的作用，这将提高我们对发生在水面上的生物过程的理解，改进对包括微生物和病毒在内的小颗粒在界面上传播速度的估计，并改进对制药和食品行业涉及粉末在液体表面破碎和扩散的过程的建模。更广泛的影响。这项研究将与教育和推广完全结合起来，涉及研究生和本科生，特别是女性和未被充分代表的少数族裔，在我们大学的课程和NJIT的研讨会上进行协同活动，并在市内大学预科学生的BBG教育计划中鼓励他们探索科学、技术、工程和数学(STEM)的职业。拟议的工作将进一步提高我们理解和模拟吸附在气液和液液界面上的颗粒的作用的能力，这些颗粒在许多物理和生物过程中发挥重要作用，例如水生植物的授粉，微生物和细菌在液体表面的传播，在流体-流体界面处形成单分子层。这个项目有可能对理解植物进化的物理机制做出重大贡献，这些植物拥有非生物二维授粉系统。

1236035SinghThe aim of this research is to investigate the physics of particle adsorption and the spontaneous dispersion of particles that occurs when particles come in contact with a fluid-fluid interface. The dispersion of small particles, e.g., flour, pollen, etc., can occur so quickly that it appears explosive, especially on the surface of mobile liquids like water. This interfacial-force-driven dispersion of particles is important because it causes particles sprinkled over a small area to almost instantaneously disperse into a monolayer over an area that is several orders-of-magnitudes larger. While the Weber and Bond numbers, and the contact angle are the important dimensionless parameters that govern the motion of particles normal to the interface, it is not completely understood what parameters govern the lateral motions of the particles. Our main objectives are: (i) use experiments and direct numerical simulations to determine the dependence on important parameters of the speed at which particles disperse, and to quantify the enhancement resulting from dispersion in the rate of spreading on liquid surfaces of small particles including microbes and viruses. (ii) Model the fluid dynamics of the two-dimensional pollination process in hydrophilous plants. (iii) Model the mechanism that causes the breakup and spreading of agglomerates on liquid surfaces.Intellectual Merit. The focus of the past studies has been on understanding the mechanisms by which particles already trapped on fluid-liquid interfaces interact. The proposed study will, for the first time, consider the role of the sudden dispersion, which will improve our understanding of biological processes occurring over the surface of water, developing improved estimates for the rate at which small particles, including microbes and viruses, spread on interfaces, and improving the modeling of processes in the pharmaceutical and food industries that involve breakup and spreading of powders on liquid surfaces. Broader Impacts. This research will be fully integrated with education and outreach, involving graduate and undergraduate students, particularly women and under-represented minorities, with synergistic activities in our courses at the university, and in workshops in NJIT, and BBG educational programs for inner-city pre-college students to encourage then to explore careers in Science, Technology, Engineering and Mathematics (STEM).The proposed work will further our capability to understand and model the role of particles adsorbed at air-liquid and liquid-liquid interfaces which play an important role in many physical and biological processes, e.g., pollination of hydrophilous plants, the spread of microbes and germs on liquid surfaces, and formation of monolayers at fluid-fluid interfaces. This project has the potential to make a significant contribution to the understanding of the physics underlying the mechanisms that have evolved in plants that possess abiotic two-dimensional pollination systems.