Interfacial instabilities in fluid films

流体膜中的界面不稳定性

• 批准号: 249488-2011
• 负责人: Pascal, JeanPaul
• 金额: $ 0.73万
• 依托单位: Ryerson University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2011
• 资助国家: 加拿大
• 起止时间: 2011-01-01 至 2012-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=479206
• 关键词: Interfacial; instabilities; fluid; films

Thin fluid films with a free surface overlying a solid material (substrate) occur frequently in a variety of situations. In industrial settings they serve to coat and protect surfaces or facilitate the transfer of mass and heat. In living organisms they perform vital functions as does, for example, the tear film covering the eye or the fluid lining of airways in the lungs. Fluid films are also encountered in the environment, such as groundwater permeating unsaturated fractured rock. Other examples are lava flows and glacial dynamics which are governed by the same physical mechanisms as fluid films with much shorter length scales. Fluid films are subject to interfacial instability, in the sense that, under certain conditions, a flow will develop resulting in non-uniformity in the thickness of the film. In time, interfacial instability can lead to the rupture of the film, and if the flow is sufficiently fast, large amplitude waves can form and propagate along the surface. The appearance of interfacial instability often has an adverse effect on the intended function of the fluid film. In coating applications connected to manufacturing processes, for example, a nonuniform film flow can result in an irregular distribution of the coating material. Similarly, fluid films serving a biological function can be ineffective if they become too thin or develop holes. In certain industrial sectors, however, interfacial instability can optimize the process. For example, in heat and mass exchangers the formation of interfacial waves improves the operation of the device due to the fact that there is an increase in the surface area of the liquid-gas interface, which facilitates the transport. A mathematical fluid flow model can be used to anticipate the conditions for the onset of instability and predict its evolution. I propose to implement theoretical models that will investigate the combined effect of various factors affecting the stability of a fluid film that are relevant in real-world situations. Notable factors that will be considered include thermal effects, the presence of surfactants (chemical solutes affecting surface tension), the permeation of fluid through a porous substrate, as well as substrates with nonplanar surfaces exhibiting undulations or corrugations.

在各种情况下，经常出现具有固体材料（底物）的自由表面的薄流体膜。在工业环境中，它们用于涂层和保护表面或促进质量和热量的转移。在活生物体中，它们可以像覆盖眼睛的泪膜或肺部气道的流体衬里一样发挥重要作用。在环境中也遇到了流体膜，例如地下水渗透到不饱和骨折的岩石。其他例子是熔岩流和冰川动力学，由与长度尺度较短的流体膜相同的物理机制控制。流体膜受到界面不稳定性的影响，从某种意义上说，在某些条件下，流动会导致膜厚度不均匀。随着时间的流逝，界面不稳定性会导致膜的破裂，如果流动足够快，大幅度波就会形成并沿表面传播。界面不稳定性的出现通常会对流体膜的预期功能产生不利影响。例如，在与制造工艺相关的涂料应用中，不均匀的膜流量可能导致涂料材料的不规则分布。同样，如果流体膜变得太薄或发展孔，则具有生物功能的流体膜可能无效。但是，在某些工业部门中，界面不稳定性可以优化过程。例如，在热量和质量交换器中，界面波的形成可改善设备的操作，因为液态加气界面的表面积增加，从而有助于运输。数学流动流模型可用于预测不稳定性发作的条件并预测其进化。我建议实施理论模型，以研究影响在现实情况下相关的流体膜稳定性的各种因素的综合作用。将被认为的值得注意的因素包括热效应，表面活性剂的存在（影响表面张力的化学溶液），通过多孔底物渗透到液体的渗透以及具有表现出波音或波纹状态的非平面表面的底物。