Spatial Heterogeneity and Imperfect Mixing in Chemical Reactions: Visualization of Density-Driven Pattern Formation
Figure 1
(a) Excitable BZ reaction medium, stirred after initial pattern formation,
2.1 mm depth. From [9, Figure 2c]. Scale bar: alternating 2.1 mm lines and
spaces. (b) Chemical model: Fe3+ and ,
2 mm depth. Scale bar: alternating 2 mm lines and
spaces. Striped patterns formed outside
the visible droplet boundary (lower left of figure). The color corresponds to
the concentration of FeSCN2+. Resolution 30 m
in photos (b) through (f). Time: about two minutes after addition of one drop of Fe3+ solution. (c), (d) Evolution of panel (b). Same experimental run, 45 and 30 second
earlier. Note pattern initiation 2 mm
behind visible wavefront (of diffusion wave) and effect of diffusion in blurring
visible boundaries as concentration gradients are reduced. (e) Same model, but 3 mm depth, early stage of pattern formation. Note visible droplet boundary in center of
figure, and larger scale that corresponds to greater depth as in (b) through (d). (f) Same model, 1 mm depth, early stage of pattern formation. Scale bar: 1 mm. Note fine structure (1 mm)
transverse to a spatial filament of the reaction, and initial excitation of 1 mm scale.
