Fluctuating Hydrodynamics for Liquid Spreading over Heterogeneous Surfaces

产品描述：了解液体在异质固体表面上的扩散是许多新兴技术（例如3D打印金属结构的能力），生物系统（植物叶子保留液体）甚至法医学（血液飞溅分析）的关键。润湿过程最显著的特征是其强烈的多尺度性质，这确保了纳米尺度和微米尺度效应对感兴趣的系统具有强烈的宏观影响。润湿的迷人的多尺度性质使其成为一个具有理论挑战性的主题，因为人们必须以计算上易于处理的方式将微观尺度与宏观尺度联系起来。为了开发一种随机计算模型，该模型能够捕获驱动非均匀表面上的宏观润湿流动的纳米尺度波动，并根据分子动力学模拟验证这一点，新奇和方法：热波动，使分子“跳”过固体中的势垒，长期以来一直被认为是动态润湿流动的潜在驱动机制。由于这种物理作用的空间和时间尺度很小，分子动力学（MD）模拟能够捕获局部动力学，并可用作基准。然而，试图将这种机制与宏观动力学联系起来，并因此进行实验，由于MD在纳米级以上的计算困难，仍然难以实现。此外，有争论的主导力量为“真实的”（即异质）表面，在表面结构中的缺陷跳跃可能比分子跳跃更重要。这些悬而未决的问题只能通过开发基于波动流体力学理论的计算模型来解决，即随机偏微分方程（SPDE），这将为理解这一系统提供急需的新能力。（EP/N 016602/1，PI：Lockerby）ii）EPSRC CDT HetSys核心培训目标：a）跨学科性-这一点至关重要，因为该项目涉及物理学领域（模型开发），计算工程与应用数学（例如SPDE）。B）稳健的软件工程--需要开发MD和SPDE计算模型，这些模型的寿命和遗产将超过项目的寿命和遗产。c）不确定性-在试图量化随机表面结构对宏观流动的影响时，将变得重要;这是该领域研究的新方向。i）主要合作伙伴将是蒙斯的表面和界面物理实验室（HetSys的合作伙伴之一），他们在润湿过程的MD方面拥有无与伦比的专业知识。ii）这项研究应该与巴黎狄德罗大学的Bruno Andreotti教授的小组合作，在异质基底的润湿方面取得了巨大的实验和理论进展，以及达姆施塔特的智能界面中心。iii）在理解动态润湿方面的任何进展都可以转化为我们与之有现有关系的工业合作伙伴，例如贝尔实验室（HetSys合作伙伴）、斯伦贝谢和阿克苏诺贝尔。

Description: Understanding the spreading of liquids over heterogeneous solid surfaces is the key to numerous emerging technologies (e.g. capabilities to 3D print metallic structures), biological systems (retention of liquids by plant leaves) and even forensic science (analysis of blood splatters). The most remarkable feature of the wetting process is its strong multiscale nature, which ensures that nanoscale and microscale effects have a strong macroscopic influence on systems of interest. It is the fascinating multiscale nature of wetting that makes it such a theoretically challenging topic, as one must connect the microscale with the macroscale in a computationally tractable manner.Aims: To develop a stochastic computational model capable of capturing the nanoscale fluctuations that drive macroscopic wetting flows over heterogeneous surfaces and validate this against molecular dynamics simulations, in collaboration with our partners in Mons.Novelty & Methodology: Thermal fluctuations, which allow molecules to 'hop' over potential barriers in the solid, have long been considered as a potential driving mechanism for dynamic wetting flows. Owing to the small spatial and temporal scales on which this physics acts, molecular dynamics (MD) simulations are able to capture the local dynamics, and can be used as a benchmark. However, attempts to connect this mechanism to macroscopic dynamics, and thus experiments, have remained elusive due to the computational intractability of MD above the nanoscale. Furthermore, there is debate over the dominant forces for 'real' (i.e. heterogeneous) surfaces, where hopping over defects in the surface structure may be more important than the molecular jumps. These open problems can only be addressed by the development of a computational model based on the theory of fluctuating hydrodynamics, i.e. stochastic partial differential equation (SPDEs), which would give new, much-needed capabilities for understanding this system.Alignment:i) EPSRC Programme Grant 'Nano-Engineered Flow Technologies: Simulation for Design across Scale and Phase' (EP/N016602/1, PI: Lockerby)ii) EPSRC CDT HetSys Core Training Objectives:a) Interdisciplinarity - will be essential as the project cuts across physics (development of models), computational engineering and applied mathematics (e.g. SPDEs).b) Robust Software Engineering - is required to develop both MD and SPDE computational models that will have lifetime and legacy beyond that of the project.c) Uncertainty - will become important when attempting to quantify the influence of the random surface structure on macroscopic flow; a new direction of research in this field.Collaborations:i) The primary partner will be the Laboratory of Surface & Interfacial Physics in Mons (one of HetSys's partners) who have unrivalled expertise in the MD of wetting processes.ii) This research should lead to collaborations with Professor Bruno Andreotti's group at Universite Paris-Diderot, where great experimental and theoretical progress has been achieved in the wetting of heterogeneous substrates, and the Centre for Smart Interfaces in Darmstadt.iii) Any progress in understanding dynamic wetting could be translated to industrial partners who we have an existing relationship with, such as Bell Labs (HetSys partner), Schlumberger and Akzo Nobel.