Results from a thermal/chemical boundary layer model in a 6 × 1 domain with Ra=10⁶, H=4 and ICD=0.02. Isotherms over composition along with surface heat flux from the full model domain are shown in (a); notice that the top of the image is stretched for visualization. The effects of a drifting chemical accumulation and of colliding chemical accumulations on heat loss are shown, respectively, in (b) and (c), both of which display ≠ar‐surface composition fields along with local surface heat fluxes (model × are shown in the lower right corners of the composition field images).