From quasi-2D to 3D Turing patterns in ramped systems

We elaborate on the transition from quasi-two-dimensional to three-dimensional Turing patterns in a chemical reaction-diffusion system confined in gradients of chemicals between two feed boundaries. This transition is observed in open spatial reactors specially designed to make possible the unfolding of a pattern sequence in one direction of the plane of observation. In this direction, the confinement of the structure is progressively relaxed. Complementary observations from two reactor geometries allow the dimensionality of the structure to be elucidated: quasi-two-dimensional and three-dimensional patterns, respectively, correspond to patterns developing in monolayers and in bilayers. Beyond the now classical hexagonal and stripe patterns, various new stable planforms are shown to result from the coupling of these two classical pattern modes which develop in two adjacent layers, with well-defined phase relations between the two pattern modes.