Jacobo Guiu-Souto

Modulation of volume fraction results in different kinetic effects in Belousov–Zhabotinsky reaction confined in AOT-reverse microemulsion

The effects of volume fraction modulations on a Belousov-Zhabotinsky reaction catalyzed by the photosensitive Ru(bpy)(3)(+2) confined in an AOT microemulsion system are analyzed. Kinetic observables such as the induction time or the initial oscillation period demonstrate two different types of correlation with the volume fraction depending on whether the system is below or above the microemulsion percolation threshold. Temporal evolution also demonstrates an exponential growth of the period with the number of oscillations independent of the volume fraction of the system.

Externally controlled anisotropy in pattern-forming reaction-diffusion systems

The effect of centrifugal forces is analyzed in a pattern-forming reaction-diffusion system. Numerical simulations conducted on the appropriate extension of the Oregonator model for the Belousov-Zhabotinsky reaction show a great variety of dynamical behaviors in such a system. In general, the system exhibits an anisotropy that results in new types of patterns or in a global displacement of the previous one. We consider the effect of both constant and periodically modulated centrifugal forces on the different types of patterns that the system may exhibit. A detailed analysis of the patterns and behaviors observed for the different parameter values considered is presented here.

Harmonic vibration on a reactive fluid at boundary layer regime modifies the Turing instability

Studies of Turing instability in a reactive fluid, known as BZ-AOT microemulsion, under external harmonic vibration, show modifications on pattern formation. The characteristics of the reactor and forcing prevent flows to occur, and therefore the transport phenomena can only be due to microscopic diffusion. In order to understand this problem, we combine the reaction-diffusion model with a mesoscopic model. The performed linear stability analysis and numerical simulations show, on the one hand, that the forcing increases the wavelength of the patterns and, on the other hand, that the system is unable to exhibit any pattern for sufficiently large forcings thus yielding to a state of homogeneous concentration.

Turing instability under centrifugal forces

Self-organized patterns are sensitive to microscopic external perturbations that modify the diffusion process. We find that Turing instability formed in a compartmented medium, a Belousov–Zhabotinski–aerosol-OT micelle reaction, responds sensitively to a change in the diffusion process. In order to modify the diffusion mechanism, we apply a centrifugal force that generates a perturbation with an anisotropic character. We find experimentally and numerically that the perturbation is able to modify the pattern and even force its disappearance. For different values of the perturbation significant changes can be seen in both the pattern wavelength and its morphology. Furthermore, for strong perturbations, the orientation of the patterns couples with the symmetry of the perturbation.