Conferences - Seminars

04DEC
2015
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  Friday 4 December 2015 11:15 GCA 331

Prix Rhyming 2014: Modelling droplets flowing in microchannels

By Dr. Mathias Nagel, ETHZ
Bio: I was born and raised in Berlin, Germany and studied Aeronautical Engineering at the RWTH-Aachen University. During my studies I spent a semester studying abroad at the Keio University in Tokyo Japan and in an internship at EADS Space Transportation in Ottobrunn near Munich. In my masters thesis (more accurately diploma thesis) I had worked on the simulation of premixed flames with a level set and reconstruction.

From 2009 to 2014 I pursued a PhD at the EPFL in Lausanne Switzerland in the Laboratory of Fluid Dynamics and Instabilities of Prof. François Gallaire. Herein I studied two-phase flows at low Reynolds and Capillary number like they often appear in Lab-On-A-Chip applications. During the course of this work I developed a numerical flow solver called "ulambator", which is now open-source.

The studies in microfluidics exposed me to some experimental work and I came to enjoy and value the close interaction of computer based model approach in close exchange with experiments and in consequence I came to join Prof. Jan Vermant in the Soft Materials group at ETHZ, where I am working since 2015 on problems related to micro-rheology.

Current projects range from building a dynamic pendent drop apparatus to simulation of complex viscoelastic interfaces in the presence of particles.

This work concentrates on the study of droplets in microfluidics, mostly performed numerically. The motivation is rooted in the existing discrepancy between the level of complexity achieved in experimental microfluidics or even Lab-on-a-chip applications and our fundamental/theoretical understanding of such experiments. For the sake of completeness, other objects than droplets, such as fibers, are also considered in this work.

We derived a simplified set of governing equations and a numerical method favoring the discretization of free interfaces. Such boundary element scheme has proven to be robust, efficient, and versatile allowing for the investigation of a wealth of theoretical and practical situations: from revisiting the well-known Saffman-Taylor instability to the theoretical prediction of the velocity of droplet in a microchannel, via the capture of droplets using microfluidic traps, the relaxation of a deformed droplet in a microchannel and the study of solid objects as the thin rigid fibers.

This numerical tool has systematically been confronted to experiments, either from the literature when available or carried out directly in the laboratory when needed. The numerical simulations have in the majority of cases proven successful in reproducing the experiments and have helped gaining a greater physical understanding of the fundamental mechanisms underpinning Lab-on-a-chip applications.

Organization Prof. François Gallaire

Contact Prof. François Gallaire

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