Promotionsvortrag Physik: „Transport in catalytic microchannels“

Ankündigung des Promotionsvortrags von: Herrn Gonçalo Filipe Cruz Antunes

Fluid flows in microconfined spaces play an increasingly important role in modern technology. Due to their large surface-to-volume ratio, the physical conditions inside microchannels are easier to control than those inside conventional batch reactors. As a result, chemical plants based on arrays of microreactors are expected to be safer and more efficient than conventional designs. Further-more, novel microfluidic devices allow for the automated manipulation of small volumes of fluids, including biological samples. Such devices can be employed in purposes such as microfabrication, inkjet printing, and sample testing in the healthcare sector.

Besides their potential for technological advances, the flow of chemically reactive fluids in catalyst-coated microchannels is a physically rich problem with many control parameters and phenome-nologies. For example, flows may be passive and set in response to an external driving, or they may be active and arise spontaneously due to a conversion of chemical energy into motion. In both of these cases, the distribution of catalyst and the shape of the channel walls are crucial parameters. We investigate their role based on lattice Boltzmann simulations and semi-analytical theories which exploit the narrowness of the channels.

Two systems will be presented: a compressible flow reactor under an external pressure drop, and an active pore that drives flows by consuming a chemical fuel. Regarding the former, we will show how introducing corrugations to the channel wall and inhomogeneities to the catalytic coating may increase the product yield in the highly-compressible regime. As for the active pore, we show how a spontaneous symmetry breaking arises when fore-aft symmetric pores are large enough. This instability enables the pore to play the role of a micromixer, a pump, and a fluidic oscillator. Finally, we show how the flow rate across fore-aft asymmetric pores exhibits discontinuous jumps and hysteresis.

(Vortrag auf Englisch)

Dem Vortrag schließt sich eine Diskussion von 15 Minuten an. Vortrag und Diskussion sind öffentlich. Diesen Verfahrensteilen folgt ein nicht öffentliches Rigorosum von 45 Minuten.