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DY: Fachverband Dynamik und Statistische Physik

DY 22: Posters I

DY 22.36: Poster

Mittwoch, 28. März 2012, 17:00–19:00, Poster A

Surfactant-induced gradients in the 3D Belousov-Zhabotunsky reaction — •Dennis Kupitz¹, Sergio Alonso², Markus Bär², and Marcus Hauser¹ — ¹Abteilung Biophysik, Institut für Experimentelle Physik, Otto-von-Guericke-Universität Magdeburg, Germany — ²Physikalisch-Technische Bundesanstalt, Fachbereich 8.4, Berlin, Germany

Scroll waves are prominent patterns formed in 3D excitable media, and they have been found to be at the basis of some types of cardiac arrhythmias. Experimentally, scroll waves dynamics is often studied by optical tomography in the Belousov-Zhabotinsky reaction, which produces CO₂ as an undesired product. Addition of small concentrations of a surfactant is a popular method to suppress or retard CO₂ bubble formation. We report that in closed reactors even these low concentrations of surfactants are sufficient to generate vertical gradients of excitability which are due to gradients in CO₂ concentration. In reactors open to the atmosphere such gradients can be avoided. Gradients are shown to induce a twist onto vertically oriented scroll waves, while a twist is absent in scroll waves in a gradient-free medium. The effects of the CO₂ gradients are explained by a numerical study, where we modified the Oregonator model to account for the production of CO₂ and for its advection against the direction of gravity. The numerical simulations confirm the role of solubilized CO₂ as the source of the vertical gradients of excitability in reactors closed to the atmosphere.

[1] D. Kupitz, S. Alonso, M. Bär, M.J.B. Hauser, Phys. Rev. E 84, 056210 (2011).