Dynamics of leaves with different wettability due to raindrop impact

PI：Jung，Sunghwan建议编号：1604424根据表面被水润湿的难易程度，它可以是亲水的，也可以是疏水的。这项拟议的研究的灵感来自于生物表面，如树叶，它们在一生中表现出不同的润湿行为，随着自然或人造污染物与其表面相互作用，它们从疏水转变为亲水。研究水滴溅落在叶片上的动力学是如何因表面特性的变化而变化的，对于了解早期灾难性的叶片损失和开发避免这种损失的方法具有重要意义。这可能会对预测食物和森林资源的水平产生进一步的影响。生物学家和生物化学家之前关于树叶脱落的大部分工作都集中在空气污染物对树叶表面的急性化学效应上。然而，叶片变得亲水性的物理机制和亲水性叶片对雨滴的响应的动力学方面都不是很清楚，这可能是雨后灾难性叶片损失的重要原因。PI建议研究树叶之间的相互作用-S的润湿性、弹性和水滴传播，灵感来自于雨滴撞击自然界中的树叶。首先，对疏水树叶向亲水树叶过渡的机理进行了探讨。其次，液滴在弯曲衬底上的传播动力学将在宏观和微观上用润湿性和下降速度来表示，这将允许估计叶片上的冲击力和液滴传播半径。最后，对叶片的S力学模数和极限强度进行了表征，以了解叶片在跌落冲击下的弯曲和扭转变形。国际残疾协会将为残疾学生追求个人和教育方面的兴趣。作为一项教育目标，国际残疾人联合会将制定研究计划，帮助残疾学生克服由于社交和沟通技能受损而在当前教育系统中遇到的困难。建议的同伴伙伴计划是为患有自闭症或其他社交障碍的学生设计的，方法是让他们与结构化环境中的典型同龄人一起接触实验室研究。包容性的环境将为学生提供结构化的研究机会，这将有助于培养与同龄人有效沟通和合作所需的信心和能力，并最终成为未来的工程师或科学家。

PI: Jung, SunghwanProposal Number: 1604424Based on how easy it is for a surface to be wetted by water, it can be hydrophilic or hydrophobic. The proposed research is inspired by biological surfaces, like leaves, that exhibit different wetting behavior in their lifetime, and turn from hydrophobic to hydrophilic as natural or man-made pollutants interact with their surface. Investigating how the dynamics of drops splashing on leaves change because of changes on surface characteristics is important for understanding early catastrophic leaf loss and developing methods to avoid it. This can have further implications on predicting levels of food and forest resources.Most of the previous work done by biologists and biochemists about shedding of leafs, has focused on acute chemical effects of air contaminants on leaf surfaces. Nevertheless, both the physical mechanism of a leaf turning hydrophilic and the dynamical aspects of hydrophilic leaves in response to raindrops are not well understood, which may significantly contribute to catastrophic leaf loss after rain. The PI proposes to investigate the interplay between a leaf?s wettability, elasticity, and drop spreading, inspired by a raindrop impacting a leaf in nature. First, the mechanism of transitioning from hydrophobic to hydrophilic leaves will be explored. Secondly, the spreading dynamics of a droplet on a curved substrate will be formulated both macroscopically and microscopically in terms of wettability and a falling speed, which will allow the estimation of an impact force and drop-spreading radius on the leaf. Finally, a leaf?s mechanical moduli and ultimate strengths will be characterized, in order to understand bending and torsional deformations of a leaf upon drop impact. The PI will pursue personal and educational interests for students with disabilities. As an educational objective, the PI will develop research programs that assist disabled students in overcoming the difficulties encountered in the current educational system, due to impaired social and communication skills. A proposed peer-buddy program is designed for students with autism or other social impairments by exposing them to laboratory research along with typical peers in structured environments. An inclusive environment would provide the students with structured research opportunities, which would help to develop the confidence and capacity needed to effectively communicate and collaborate with their peers, and eventually become future engineers or scientists.