Multi-Scale Simulation of Droplets on Solid Surfaces: Superhydrophobicity and Superspreading

摘要提案编号：CBET-07300987主要研究者：Kristen A. Fichthorn大学/机构：宾夕法尼亚州立大学，题目：固体表面液滴的多尺度模拟：超疏水性和超扩散本项目包括使用分子动力学（MD）模拟和混合MD和连续计算的液体滴在固体基底上的扩散的调查。这些研究解决了理解铺展和毛细流动的三个主要挑战：（1）理解表面活性剂介导的铺展机制;（2）阐明粗糙和图案化表面上的超疏水性机制;（3）开发一种模拟方法，将扩散所涉及的巨大时间和空间尺度结合起来，范围从在接触线处操作的分子水平动力学机制到宏观流体动力学机制。分子动力学模拟将有助于揭示重要的分子细节，而混合模型将有助于深入了解驱动扩散的分子和流体动力学机制之间的相互作用。液滴在固体表面上的铺展在许多工业应用中起着重要作用，例如涂覆、涂漆、喷涂、模塑、纤维制造和微流体，以及在生物应用中，例如表面活性剂替代疗法。这一领域的大多数理论研究都采用了连续介质模型，在移动接触线处缺乏微观细节。分子动力学模拟将提供分子水平的细节重要的理解表面活性剂介导的传播和超疏水性。这些细节在表面活性剂分子的选择或设计以及疏水表面的有效产生中是重要的。拟议的研究还解决了这一领域的一个明显挑战：开发一种模拟方法，该方法结合了巨大的时间和空间尺度，从大规模对流到接触线的分子细节。多尺度模拟方法的发展将使我们能够充分捕捉微观过程和宏观事件之间的复杂相互作用，在蔓延和其他涉及移动三相接触线的表面。除了研究生和博士后培训以及本科生参与计算研究之外，拟议研究的各个方面将纳入关于界面传输现象的研究生课程。Borhan和Fichthorn教授将合作教授计算方法的研究生课程，向学生介绍多尺度建模和混合MD连续方法。最后，PI将通过在第六届跨学科运输现象国际会议上组织关于润湿和毛细现象的研讨会，推进界面运输的多尺度建模和理解。

ABSTRACTProposal Number: CBET- 07300987Principal Investigator: Kristen A. FichthornUniversity/Institution: Pennsylvania State Univ.Title: Multi-Scale Simulation of Droplets on Solid Surfaces:Super-hydrophobicity and Super-spreadingThis project consists of an investigation of the spreading of liquid drops on solid substrates using molecular-dynamics (MD) simulations and hybrid MD and continuum computations. These studies address three major challenges in understanding spreading and capillary flows: (1) Understanding mechanisms of surfactant-mediated spreading; (2) Elucidating mechanisms of Super-hydrophobicity on rough and patterned surfaces and; (3) Developing a simulation methodology that incorporates the vast temporal and spatial scales involved in spreading, ranging from molecular-level kinetic mechanisms operating at the contact line to macroscopic hydrodynamic mechanisms. The MD simulations will be beneficial in unlocking important molecular details, while the hybrid model will allow insight into the interplay between molecular and hydrodynamic mechanisms that drive spreading.Intellectual Merit: Droplet spreading on solid surfaces plays an important role in numerous industrial applications, such as coating, painting, spraying, molding, fiber manufacturing, and Micro-fluidics, as well as in biological applications, such as surfactant replacement therapy. Most theoretical studies in this area have employed continuum models that lack microscopic details at the moving contact line. The MD simulations will furnish molecular-level details important for understanding surfactant-mediated spreading and super-hydrophobicity. These details are important in the choice or design of surfactant molecules and the effective creation of hydrophobic surfaces. The proposed research also addresses a clear challenge in this area: The development of a simulation methodology that incorporates the vast temporal and spatial scales, ranging from large-scale convection to molecular details at the contact line. Development of a multi-scale simulation method will allow us to fully capture the intricate interplay between microscopic processes and macroscopic events in spreading and other surface involving moving three-phase contact lines.Broader Impacts: In addition to graduate student and postdoctoral training and the involvement of undergraduate students in computational research, aspects of the proposed research will be incorporated into a graduate course on interfacial transport phenomena. Professors Borhan and Fichthorn will team-teach a graduate course on computational methods to introduce students to multi-scale modeling and the hybrid MD-continuum method. Finally, the PIs will advance the state of the art in multi-scale modeling and understanding of interfacial transport by organizing a symposium on wetting and capillary phenomena at the 6th International Conference on Interdisciplinary Transport Phenomena.