Convective structures in a two-layer gel-liquid excitable medium

The onset of convection due to wave propagation is investigated in the framework of the Belousov-Zhabotinsky reaction. Numerical calculations are based on a three variable Oregonator model coupled with the Navier-Stokes hydrodynamic equations under the Boussineq approximation for a system consisting of two layers, a liquid and a gel, both in close contact through an interface where chemical concentration exchange is allowed. The influence on the formation of convective rolls associated to wave front propagation is studied in terms of the exchange rate through the interface, the liquid layer width, and the coupling strength between the fluid flow and chemical dynamics. Waves are initiated on the surface of the gel and this perturbation is allowed to propagate into the liquid initiating either two counterrotating convective cells (at both sides of the front) or a disordered pattern.