Shearless turbulent mixing. Visualization of the kinetic energy in the central part of the mixing in a plane (x, y₁), (y₂ = const). The higher energy region has a Taylor microscale Reynolds number equal to 150, the energy ratio is 6.7. For more details on the flow, see the paper in Physical Review Letters (2011).

The time evolution of the mixing layer can be seen in this movie, which shows the kinetic energy in the first 6 eddy turnover times.

Shearless turbulent mixing. Visualization of the kinetic energy in a plane. The higher energy region has a Taylor microscale Reynolds number equal to 45.

- energy ratio 6.7, uniform integral scale (see movie).

- as above, but the integral scale gradient is opposite to the kinetic energy gradient (see movie).

Both movies last about 9 eddy turnover times.

For more details on these simulations, refer to JFM (2006).

Passive scalar diffusion through a kinetic energy gradient. The higher energy turbulent region (Re_λ=150) is on the left of the image, the lower energy region is on the right.

The time evolution of the scalar diffusion is shown by the following movies:

• Re_λ=150 (600²x1200 simulation, colors as in the figure)
• Re_λ=150 (600²x1200 simulation)
• Re_λ=250 (1024²x2048 simulation)

For more details on the flow, see JoT 2014 and the proceedings of ETC-13

Passive scalar diffusion through a kinetic energy gradient in a two dimensional flow. The higher energy turbulent region (Re_λ=150) is on the left of the image, the lower energy region is on the right.

The time evolution of the scalar diffusion is shown by the following movies:

• 1024² simulation with hyperviscosity
• 2048x4096 NS simulation, Rel=3500.

Kinetic energy profiles, comparison between the two-dimensional and the three-dimensional flow. The black vertical lines indicates the borders of the mixing layers, the vertical green line indicate the position of maximum intermittency (see movie)

Vorticity field, two dimensional simulation (see movie).

Vorticity field in the presence of a stable stratification (Fr=10), preliminary result from a two dimensional simulation (see movie).

Vorticity field in the presence of a stable stratification (Fr=0.1), preliminary result from a two dimensional simulation (see movie).

Diffusion of vapour through an horizontal interface in a stratified environment. The image shows a vertical plane (see also the movie).

For more details, see the proceedings of UIT-32