A joint analytical and experimental investigation is to be conducted of the viscous decay, evolution and interaction of vortex couples at large Reynolds number. Analytically, boundary layer ideas are used to derive their behavior from known inviscid solutions. The interaction of vortex couples with weak background vorticity or shear is studied using singular perturbation theory. By studying mixing in the large Peclet number limit, estimates on the efficiency of vortex couples in transport are derived. The experiments employ a novel use of stratification to create two-dimensional flows. Mixing is studied quantitatively by the optical tracking of tracer particles and dye. Data processing determines the velocity and vorticity fields as they evolve. Vortex couples, localised dipolar regions of vorticity, possess nearly closed streamlines, are self-propagating, and persist for long times. Consequently, they efficiently transport vorticity, momentum, heat and contaminants. Vortex couples arise in the shear layers and plumes observed in atmospheric chemistry, ocean mixing, convective cooling, and turbulent transport and mixing.
