Figure 2. Stages of convective transport.

(a) Initially, tracers are uniformly dispersed throughout the domain and the hydrogen peroxide concentration (shown by the colour bar) is zero. (b) The reagent, diffusing through the left wall, produces density variations resulting in a fluid flow that transports tracers. The catalyst at the bottom wall decomposes the reagent, creating a concentration (density) gradient. (c) After the reagent is consumed, the flow stops with areal concentration of tracers n/n₀ increasing toward the right wall as shown by the red squares. (The red squares form a histogram, where the width of one bin corresponds to 500 μm.) Simulations were performed for C₀=0.1 M and r_max=1.7 × 10⁻⁵ mol m⁻² s⁻¹.