High Schmidt-number mixing (Sc=1024) by three-dimensional round turbulent jet, passive scalar concentration field. Mixing rate of weekly-diffusive particles by three-dimensional round turbulent jet. Helium mixture fraction in helium-air plume. Subgrid-scale scalar-energy production in helium-air plume. Mixture fraction in A = 0.5 Rayleigh-Taylor flow. Mixture fraction isocontours at 0.95 and 0.05, colored by subgrid-scale energy production in A = 0.5 Rayleigh-Taylor flow. Evolution of mixture fraction field in A = 0.94 Rayleigh-Taylor flow. Bubble mixture fraction isocontours at z = 0.95 colored by subgrid-scale energy production in A = 0.94 Rayleigh-Taylor flow. Spike mixture fraction isocontours at z = 0.05 colored by subgrid-scale energy production in A = 0.94 Rayleigh-Taylor flow.