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.
