Computational Fluid Dynamics in Microfluidic Systems

Computer simulations are an indispensable tool in microfluidics because of the lack of analytical solutions. We have developed a simulation tool in Matlab based on the finite element method (FEM). At the present stage, the tool can be employed to handle general second order partial differential equations in two dimensions. The tool has been applied to model incompressible laminar flow, and it has been tested on the classical problem of flow over a backward-facing step. Also the tool has been employed to model non-Newtonian blood flow in a microchannel, in relation to an experiment performed by Lennart Bitsch, using micro particle-image velocimetry (μPIV) measurements to map out the velocity profile of blood flowing in a thin glass capillary. The joint work has resulted in two conference proceedings [1, 2] and a paper submitted to Experiments in Fluids [3]. Finally we have considered the problem of electroosmotic flow in a pore system on the submicron scale where the Debye layer overlap is non-neglible. At the time of writing the results are still preliminary, yet they demonstrate that our FEM tool is general enough to accomodate for more complex problems occuring in the field of microfluidics.