Numerical Study of Electrokinetic Bioparticle Transport Through Fluid-Structure-Electric Interaction

该建议旨在开发一种新的计算框架，以模拟涉及复杂的流体-结构-电相互作用的微流体装置中的电动生物粒子传输。由于多物理场和多尺度现象的复杂性，数值计算中必须解决的几个重要问题是：（1）流固耦合引起的数值刚度和收敛性问题：（2）流动与可变形动边界相互作用引起的尾迹、分离和涡等非定常现象的求解;（3）强电-结构相互作用对收敛性和精度的挑战。研究人员和她的团队建议使用格子玻尔兹曼方程（LBE）进行流体运动，因为它的准确性（低耗散/低色散和更好的各向同性）和计算优势，包括其出色的并行可扩展性，不需要求解耗时的椭圆泊松型方程的压力场，并且易于在笛卡尔网格上表示复杂的边界。沉浸边界法（IBM）被选为跟踪的变形移动边界，其易于实现，而无需重新网格生成的贴体网格。采用松弛法和多重网格法求解由拉普拉斯方程表示的电场。该提案的一个中心主题是通过将这些方法与其数值分析相结合的更严格的数学公式化，以及通过将现有的数值算法应用于新的高效数值技术的开发，来提高LBE、IBM和多重网格技术的能力。对于生物医学、制药和环境工业是重要的。对生物颗粒传输的良好控制是LoC工作原理的基础。例如，可以使用所提出的数值框架来证明通过微流体储库中的可变形性的电细胞分离，这将有利于影响人类细胞的生物力学特性的病原体的廉价即时诊断，例如疟疾中寄生虫感染的红细胞。该项目将补充和推进微流体装置中粒子电动力学的现有知识，并为未来生物粒子操纵微装置的设计和电气控制奠定流体力学基础。此外，这项拟议的研究将与本科和研究生教育计划紧密结合。

This proposal aims to develop a new computational framework to simulate electrokinetic bioparticle transport in microfluidics devices involving complex fluid-structure-electric interactions. Due to the complicated nature of multi-physics and multi-scale phenomena, several important numerical issues have to be addressed: (1) Numerical stiffness and convergence challenges due to the strong fluid-structure interactions; (2) Resolution of unsteady phenomena such as wakes, separation and vortices induced by interactions of flows with deformable moving boundaries; (3) Convergence and accuracy challenges imposed by the strong electric-structure interactions. The investigator and her team propose to use the lattice Boltzmann equation (LBE) for the fluid motion because of its accuracy (low dissipation/low dispersion and better isotropy) and computational advantages including its excellent parallel scalability, absence of the need to solve a time consuming elliptic Poisson-type equation for the pressure field, and ease of representation of complex boundaries on Cartesian grids. The immersed boundary method (IBM) is chosen to track the deformable moving boundaries for its ease of implementation without re-meshing to generate the body-fitted mesh. Relaxation and multigrid methods are used to solve the electric field represented by Laplace equation. A central theme of this proposal is to advance the capability of LBE, IBM and multigrid techniques through a more rigorous mathematical formulation of these methods combined with their numerical analysis, as well as through the application of existing numerical algorithms in conjunction with the development of novel efficient numerical techniques.One of the main motivations for this study comes from the Lab-on-a-chip (LoC) application, important for bio-medical, pharmaceutical, and environmental industries. Well-controlled manipulations of bio-particle transport are the basis of the working principle of LoC. For instance, electrical cell separation by deformability in a microfluidic reservoir can be demonstrated using the proposed numerical framework, which will benefit inexpensive point-of-care diagnostics of pathogens that affect the biomechanical properties of human cells such as parasite-infected red blood cells in malaria. The project will complement and advance the current knowledge of particle electrokinetics in microfluidic devices, and build the fluid mechanics foundation for the design and electric control of future bioparticle manipulation microdevices. In addition, this proposed research will be intimately integrated with undergraduate and graduate education programs.