This is an animation of a 3-D direct numerical simulation of suspended sediment transport over a 2-dimensional dune. The top frame is sediment concentration. The middle frame is cross-stream vorticity, and the bottom frame is vertical velocity minus the time averaged vertical velocity. The calclulation was performed by direct numerical simulation of the turbulence field followed by the simulation of motion of a very large number of individual particles. Pulses of suspended sediment are seen to coincide with large vortical structures produced by flow separation.

The animation is run by Java applet:  Copyright (C) 1998-1999 by Klaus Ehrenfried. Click on the animation first and then you can manipulate the playback properties with the following commands.
 
 
Key Function
Running Stopped
SPACE-BAR Stop Restart
Dot (.) Stop & Set forward play Step forward & Set forward play
Comma (,) Stop & Set reverse play Step backward & Set reverse play
Plus (+) Increase animation speed
Minus (-) Decrease animation speed
Null (0) Set initial animation speed
(R) or (r) Toggle play direction: backward/forward