This is an animation of a simulation of suspended sediment transport in a river with two channel expansions and mid-channel bars. The upper part of the animation shows fluid particle tracers that follow the depth-avergaed velocity. The lower part of the animation is the instantaneous depth-integrated suspended sediment concentration. The flow was calculated by numerical solution of the shallow water equations. The suspended sediment is modeled by a discreet particle method. Wherein, each modeled particle represents a fixed number of actual sediment particles. The lateral motion of a particle is set to that of the modeled lateral flow velocity, where the velocity profile is assumed to be logarithmic.  The vertical motion of the particles are modeled as a random walk process with the settling velocity subtracted at each time-step. Because there is no assumption of local equilibrium of the vertical concentration profile with the local stress, the model produces realistic adjustment of vertical concentration profiles as the particles move from areas of high to low boundary shear stress, or vice-versa.
 

The animation is run by a 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