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SYSE: Simulation and experiment

SYSE 2: Poster (gemeinsam mit SYCN und CPP)

SYSE 2.9: Poster

Dienstag, 25. März 2003, 19:00–21:00, ZEU/250

Instabilities of density fingers at a monostable chemical front in a Hele-Shaw cell — •Osamu Inomoto, Andre Schilling, and Stefan Müller — Abteilung Biophysik, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg

A buoyancy-driven finger formation and its development at a monostable chemical front in a thin aqueous layer were studied experimentally, using the iodate-arsenous-acid-reaction. At an early stage of the front evolution, the growth dynamics of the fingers is described with a linear analysis of the Navier-Stokes-Darcy equation, and their growth rates are well fitted to an exponential curve. We performed experiments changing the concentration of iodate, which controls the density change during the reaction, and we observed an increase of the growth rates due to this parameter. The results were compared to a model including cubic reaction, diffusion, and the hydrodynamics [1]. On the other hand, at later stages of the development, merging and splitting of the fingers are observed. For this regime, a nonlinear analysis is necessary. We found out experimentally that such nonlinear behavior is strongly coupled to the velocity and the curvature of the finger tips, which are both affected by the interaction between the fingers.

[1] A. De Wit, Phys. Rev. Lett., 87, 054502 (2001).