Numerical simulation and mixing characterization of Taylor bubble flows in coiled flow inverters

Abstract

The here presented work is dedicated to the development of a software analysis tool specialized for Taylor bubble flows in a wide range of applications and covering a variety of geometrical realizations. Accordingly, a higher order FEM based interface tracking simulation software has been designed which due to the underlying isoparametric discretization and interface aligned mesh construction allows a semi-implicit treatment of the surface tension force term. The such designed numerical framework guarantees only a negligible amount of mass loss rate resulting in suitability of the tool for long time-scale simulations. Exploiting these numerical advantages the software has been applied for the system of Coiled Flow Inverter (CFI) capillaries characterized by a range of coil diameters and Reynolds numbers for which the pseudo-periodic flowfield has been obtained and extracted for further mixing quantification studies by the help of particle tracking based analysis. In the framework of this postprocessing analysis such a suitable transformation of the results has been applied which reveals the most important features of the characteristic flow patterns and makes it possible to qualitatively but even quantitatively characterize the behavior of the established flow patterns. Therefore, such a combination of robust CFD techniques together with the respective process performance quantification makes this approach suitable for tailored process design.