Damping and clustering into crowded environment of catalytic chemical oscillators

A system formed by a crowded environment of catalytic obstacles and complex oscillatory chemical reactions is studied. The obstacles are static spheres of equal radius, which are placed in a random way. The chemical reactions are carried out in a fluid following a multiparticle collision scheme where the mass, energy and local momentum are conserved. Firstly, it is explored how the presence of catalytic obstacles changes the oscillatory dynamics from a limit cycle to a fixed point reached after a damping. The damping is characterized by the decay constant, which grows linearly with volume fraction for low values of the mesoscale collision time and the catalytic reaction constant. Additionally, it is shown that, although the distribution of obstacles is random, there are regions in the system where the catalytic chemical reactions are favored. This entails that in average the radius of gyrations of catalytic chemical reaction does not match with the radius of gyration of obstacles, that is, clusters of reactions emerge on the catalytic obstacles, even when the diffusion is significant. (C) 2018 Elsevier B.V. All rights reserved. (AU)