Thin-film flows over topographically patterned surfaces: Free-surface characteristics, atomization, and cleaning

0854046斯通该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助。 流体在粗糙表面上的流动是流体动力学中一类重要且具有挑战性的问题，无论是工业应用还是自然界的例子。许多材料和产品具有设计的表面纹理或由于自然侵蚀而演变的表面纹理。表面纹理的几何特征可以是随机的，在表面特征之间仅具有有限的相关性，或者为了装饰的原因、为了摩擦控制或为了改善表面的粘合/摩擦性质而通过具有图案或结构的机加工工艺制成。纹理表面附近的速度场取决于图案的纹理振幅和波长以及流体膜的厚度。这种纹理尺度的速度分布对许多工艺至关重要，例如薄膜涂覆、表面冷却、清洁和干燥。PI将进行系统的实验并开发理论模型，以探索液体薄膜流动，其中薄膜厚度与表面纹理深度的最大特征尺寸相当。这里三维效应是重要的，我们也关注的现象，在流动的某些方面包括惯性效应。将强调由射流冲击表面驱动的流动，例如在许多涂层和清洁过程中很重要。这种流动对于理解和描述诸如燃料燃烧中的雾化的应用是重要的。这项研究将彻底检查新的实验观察，如多边形跳跃发生在流在粗糙的表面，在光滑的基板上获得熟悉的圆形水跃。作为另一个实例，多边形自由片是雾化的前体。PI预计揭示操纵薄膜流动的一般原则，使用图案化基板的地形特征。系统的实验研究的流体和流动参数的物理化学性质，以及涂层流的微纹理基板的几何特征，和相关的片流将耦合与建模和模拟适当的自由表面运动。PI将继续让本科生参与研究，包括与过去六年来经常参加PI研究小组的代表性不足的群体的学生合作。几个研究主题将为PI的外联工作提供示范材料，包括公共讲座，如PI为儿童及其父母创建的年度假日讲座（现在开始第8年），以及为当地公立学校学生和教师进行的科学演示。

0854046 StoneThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). Fluid flows over rough surfaces constitute an important and challenging class of problems in fluid dynamics with both industrial applications and natural examples. Many materials and products have a surface texture by design or one that evolves due to natural erosion. The geometric features of the surface texture may be random, with only limited correlations between surface features or made through a machining process with a pattern or structure for decorative reasons, for frictional control, or to improve the adhesive/frictional properties of the surface. The velocity field near a textured surface depends on the texture amplitude and wavelength of the pattern and the thickness of the fluid film. This texture-scale velocity distribution is critical to many processes, such as coating with thin films, surface cooling, cleaning, and drying. The PI will perform systematic experiments and develop theoretical models to explore liquid thin-film flows where the film thickness is comparable to the largest characteristic dimension of the depth of the surface texture. Here three-dimensional effects are significant, and also we focus on phenomena where some aspects of the flow include inertial effects. Flows driven by jet impact on the surface, such as is important in many coating and cleaning processes, will be emphasized. Such flows are important to understand and describe for applications such as atomization in fuel combustion. The study will thoroughly examine new experimental observations, such as the polygonal jump occurring in flow over a rough surface, in contrast to the familiar circular hydraulic jump obtained on a smooth substrate. As another example, polygonal free sheets are precursors to atomization. The PI anticipates uncovering general principles for manipulating thin-film flows using topographic features of a patterned substrate. A systematic experimental study of the physicochemical properties of the fluids and flow parameters, as well as the geometric features of the micro-textured substrates on coating flows, and related sheet flows will be will coupled with modeling and simulations appropriate to the free-surface motions. The PI will continue to involve undergraduates in research, including working with students from underrepresented groups who have participated regularly in the PI's research group the past six years. Several of the research themes will provide demonstration material for the PI's outreach efforts involving public lectures such as the yearly holiday lecture created by the PI for children and their parents (now starting its 8th year), and science demonstrations for local public school students and teachers.