CAREER: Investigation of Marangoni and evaporative effects in microscale free-surface flows over uneven topography

Award AbstractThe的制造和操作的微型设备，在微电子学，微型化的分析设备和医疗技术中有重要的应用，需要一个详细的了解表面上的液体膜动力学与化学，地形和温度的异质性。 由于液体-空气界面是可变形的，具有不断变化的形状，这些不均匀性对薄膜的综合影响可能难以预测，并导致迷人的动力学行为。 该补助金将促进对导致液体-空气界面不均匀性的机制的更详细的了解，并控制其潜在的不良影响，其实际好处是能够进一步小型化和开发用于许多应用的微型设备。 数学模型将被用来获得挥发性液体膜流动的表面不均匀的地形和非均匀加热的基本理解。 目前的研究有三个组成部分。 (1)第一个是量化的表面张力梯度的影响所造成的温度变化，在涂层流动的树脂溶解在挥发性溶剂在表面上的地形特征。这些是基于连续薄膜沉积和光刻的微制造工艺的基本组成部分。 (2)第二个组成部分是要确定最近观察到的溪流不稳定性的薄膜流动的差异加热表面，这在许多微尺度应用与传热抑制衬底的地形的影响。 (3)第三部分是了解不均匀加热、基底润湿性和表面活性剂对纹理表面上液体膜的流平、干燥和破裂的影响。 这些动力学对于涂层应用和涉及加热壁上的薄膜的MEMS器件至关重要。 教育和外联工作旨在吸引更多的学生从事研究生研究和工程职业。 研究和教育将通过微流体和界面流体动力学的新课程的开发整合;在核心化学工程课程和实验室中引入独立的，基于研究的模块，以提高学生对研究生院和建模研究的兴趣;并为本科生扩大研究机会。 通过为新英格兰教师举办马萨诸塞大学科学、技术、工程和教育工程讲习班，并通过对少数族裔和低收入高中学生的辅导，这些外联活动以当地高中为目标。 在液体-空气界面的流体动力学不稳定性引起的复杂图案的例子将被用来帮助激发学生对科学和工程的兴趣。

Award AbstractThe fabrication and operation of micro-devices, which have important applications in microelectronics, miniaturized analytical devices, and medical technology, require a detailed understanding of liquid film dynamics on surfaces with heterogeneities in chemistry, topography, and temperature. Because the liquid-air interface is deformable with an evolving shape, the combined effects of these heterogeneities on the film can be difficult to anticipate and lead to fascinating dynamical behavior. This grant will facilitate the development of a more detailed knowledge of mechanisms that lead to non-uniformities of the liquid-air interface and the control of their potentially undesired effects, with the practical benefit of enabling the further miniaturization and development of micro-devices for numerous applications. Mathematical models will be used to gain a fundamental understanding of volatile liquid films flowing over surfaces with uneven topography and non-uniform heating. The present studies have three components. (1) The first is to quantify the effects of surface tension gradients caused by temperature variations in coating flows of resin dissolved in volatile solvent over surfaces with topographical features. These are essential components of microfabrication processes based on successive film deposition and photolithography. (2) The second component is to determine the effects of substrate topography on the suppression of recently observed rivulet instabilities in films flowing over differentially heated surfaces, which arise in many micro-scale applications with heat transfer. (3) The third component is to understand the effects of non-uniform heating, substrate wettability, and surfactants on the leveling, drying, and rupture of liquid films on textured surfaces. These dynamics are crucial to coating applications and MEMS devices involving thin films on heated walls. Educational and outreach efforts are aimed at attracting more students to postgraduate research and engineering careers. Research and education will be integrated through the development of a new course on microfluidics and interfacial hydrodynamics; the introduction of self-contained, research-based modules in core chemical engineering courses and labs to enhance student interest in graduate school and modeling research; and the expansion of research opportunities for undergraduates. The outreach activities target local high schools through UMass STEM-Ed engineering workshops for New England teachers and through the mentoring of minority and low-income high school students. Fascinating examples of intricate patterns induced by hydrodynamic instabilities at liquid-air interfaces will be used to help motivate student interest in science and engineering.