Multiphase flow for microfluidics
The generation of small drops is a recent topic in biomedical, pharmaceutical and process engineering. For example drug delivery often requires small drops to enhance the surface between the drug and the surrounding fluid. There is a manifold of techniques to generate these droplets. However, the complex mechanism underlying multiphase flow in micro channels is still not fully described. Since the chemical reaction takes place at the interface between both phases, the precise description of the fluid flow in both phases and the interaction at the interface is the key to understand and optimize the underlying mechanisms. Astigmatism-PTV is a method that allows to measure with a single camera the fully three-dimensional, three-component velocity field. The technique was applied to measure the shape of an oil droplet inside a micro channel along with the internal 3D flow field of the droplet induced by the surrounding fluid. For the results shown at the right, particles were only distributed within oil-droplets. The shape of the droplet was reconstructed by the volumetric particle positions and the velocity was estimated tracking the same particles in consecutive frames of the same dataset. The procedure allows the simultaneous determination of the shape and the droplet velocity as well as the inner flow field and offers a great potential for current research.
Contacts: Dr. Christian Cierpka