Optimizing diffusion-driven flow in a fissure

Diffusion-driven flow arises when a stably stratified fluid is bounded by an inclined wall. For a stratified fluid in an inclined fissure, in which fluid is confined to a gap between two inclined parallel walls, the flow field is determined by the gap width and the angle of inclination. When the gap width is much wider than the buoyancy layer thickness, the problem reduces to that of a semi-infinite fluid. As the gap width decreases, interaction between the boundary layer flows on the upper and lower walls increasingly influences the velocity profile, affecting transport within the fissure. We have obtained supporting experimental results that show these trends, demonstrating the existence of optimum conditions for dye transport. © 2005 American Institute of Physics. DOI: 10.1063/1.2142833