Chaotic mixing in a microfluidic droplet

(Bringer et al., 2004)

The aim of this study is to investigate the chaotic mixing occurring in a droplet flowing trough a microfluidic winding channel.
For real chemical and biological applications, the correct mixing of the reagents inside the droplet is crucial. However, due to the low Reynolds number, typical for microfluidic systems, only diffusive mixing occurs in a laminar straight channel. It has been shown that rapid mixing at low Reynolds number is possible by using chaotic advection. For a small channel height-to-width aspect ratio, the flow is mainly two-dimensional and chaos may be induced by a time-dependent flow, which can be generated by a winding channel.
With this project we would like to better understand the origin of the mixing by performing numerical simulations using the open-source solver Ulambator and by modeling the flow field using analytical solutions. Different winding channel geometries will be investigated and a parametric study will be performed. The obtained flow fields will be analysed in the context of Lagrangian coherent structures (LCSs) using the finite-time Lyapunov exponent so as to extract the skeleton of the flow and to improve mixing.
Some basic programming skills (mainly MATLAB) are preferable

Supervisor: Gioele Balestra