RUI: Electrohydrodynamic Flow in Microchannels

具有显著电导率梯度的电驱动流对于各种片上分析是至关重要的，例如场放大样品堆积、等电聚焦和各种样品和缓冲流的电导未知或控制不佳的电泳分析。在某些应用中，如低雷诺数微通道混合，不稳定性是可取的，而在其他应用中，如场放大样品堆积(FASS)，不稳定性是不可取的。根据这笔赠款开展的工作将建立在对规则流动通道中基本不稳定机制的理解基础上，并侧重于开发新的计算工具，以评估更复杂和现实的几何形状中的电动流动。主要的三个研究方向是：(1)对电动流动进行高保真的直接数值模拟，以探索输运的统计特性。这些数值模型将用作更易处理和计算效率更高的模型的基线比较，(2)使用商业有限元软件将当前的数值方法扩展到包括简单通道流动以外的几何形状，以及(3)通过交流电场、表面修改或通道几何形状来优化和控制混合速率。这些组合机制有望成为一种快速、被动的低雷诺数混合机制。这项研究计划将在富兰克林·W·奥林工程学院实施，这是一所新的本科学院，其中44%的学生是女性。这笔助学金的一个重要的更广泛的影响是这些学生直接参与实现研究目标。本科生将参与修改现有的计算模型，开发针对大量计算数据的分析和可视化工具，并帮助使用商业有限元软件将这项研究扩展到新的应用领域。该项目还将为本科生提供体验研究的机会，并提高他们对研究生学习的兴趣。

Electrically driven flows with significant conductivity gradients are critical to a variety of on-chip assays such as field amplified sample stacking, isoelectric focusing, and electrophoretic assays where conductivities of various sample and buffer streams are either unknown or poorly controlled. In some applications, such as low Reynolds number microchannel mixing, the instability is desirable and in other applications, such as field amplified sample stacking (FASS) the instability is undesirable. The work performed under this grant will build upon the understanding of the basic instability mechanisms in regular flow channels and focus on developing new computational tools for evaluating electrokinetic flows in more complex and realistic geometries. The three main research thrusts are: (1) Performing high fidelity, direct numerical simulations (DNS) of electrokinetic flows in order to explore the statistics of the transport. These DNS will serve as a baseline comparison for more tractable and computationally efficient models, (2) Extending current numerical methods to include geometries other than simple channel flows using commercial finite element software, and (3) Optimization and control of mixing rates through AC electric fields, surface modification, or channel geometry. These combined mechanisms hold promise as a rapid, passive mechanism for low Reynolds number mixing. This research program will be implemented at the Franklin W. Olin College of Engineering, a new undergraduate college, in which 44% of the students are female. A significant broader impact of this grant is direct involvement of these students in carrying out the research objectives. Undergraduate students will be involved in modifying the existing computational models, developing analysis and visualization tools for large sets of computational data, and helping to expand this research to new application areas using commercial finite element software. The project will also afford undergraduates the opportunity to experience research, and to enhance their interest in graduate study.