Fluid Flows at the Nano Scale: from Molecular Dynamics to Hydrodynamics

流体在纳米尺度上的流动对纳米技术提出的一些创新工程应用至关重要，例如使用纳米纤维进行海水淡化，以及废水污染物的控制和处理。然而，这些高度受限的小规模流动的重要方面尚不清楚。这是因为具有无滑移边界条件的传统Navier-Stokes方程通常不适用（因为流动远离平衡），或者物理条件太复杂且系统特定，无法做出准确的先验假设或简化。因此，我们在这个项目中的愿景是，在这些极端条件下提供对流体动力学的新理解，超越目前的模型。为了做到这一点，我们将创建一个独特的数值工具来研究工程流动（气体和液体）在最小的尺度。利用我们在英国对非平衡微尺度气体流动建模的独特专业知识，我们将开发一种新的混合模型，将任意几何形状的流动的分子动力学（MD）描述与流体动力学描述相结合。迄今为止，混合/MD技术仍停留在化学和物理领域，但我们的重点将放在工程科学的问题上，包括建模高通量选择性过滤，以及探索如何操纵疏水性、传热、化学和其他流体/表面性质，以生产“智能”表面和结构。

How fluid flows behave at the nano scale is critical to some innovative engineering applications proposed for nanotechnology, such as using nano fibres for desalination, and waste water contaminant control and treatment. However, important aspects of these highly-confined, small-scale flows are not understood. This is because the conventional Navier-Stokes equations with no-slip boundary conditions often do not apply (as the flow is far from equilibrium) or the physical conditions are too complex and system-specific to make accurate a priori assumptions or simplifications. Our vision in this project is, therefore, to provide new understanding of fluid dynamics under these extreme conditions --- beyond that of current models. To do this we will create a unique numerical tool to investigate engineering flows (both gas and liquid) at the smallest scales.Drawing on our distinctive expertise in the UK of modelling non-equilibrium micro scale gas flows, we will develop a new hybrid model that couples a molecular dynamics (MD) description of the flow in arbitrary geometries to a hydrodynamic description. To date, hybrid/MD techniques have remained in the domain of chemistry and physics but our focus will be on problems in engineering science, including modelling high-throughput selective filtration, and exploring how we can manipulate the hydrophobicity, heat transfer, chemical and other fluid/surface properties to produce 'smart' surfaces and structures.