This is an animation of a numerical simulation, where a passive tracer is transported by the flow inside a cuboid pipe with
periodic walls. Turbulent dynamics develop spontaneously from a laminar initial condition. Arrows display the velocity of the
flow, while the tracer is shown as a black "smoke".
Animation of another simulated turbulent flow
Same as above,
however, there is no "pipe" (the domain is a cuboid with free outflow
outlet and side panels, only the inlet patch is a "wall"). Also, only
the tracer is visualized. For smoothness, this video has interpolated
frames between each pair of original frames, which causes mild visual
artifacts in the beginning of the video.