Some videos of topical interest

Here are links to several Youtub videos on fluid flow that you may
find informative.

Turbulent flow in a pipe- note the rapid onset of mixing
http://www.youtube.com/watch?

v=NplrDarMDF8&feature=PlayList&p=23D938B8B55F49E8&index=1

compare this to the case of laminar flow in a pipe and note the long
steady streamline
http://www.youtube.com/watch?v=KqqtOb30jWs&feature=related

USGS Bedforms animations- this is a great site showing work by Dave
Rubin at Co at the USGS looking at ripple formation, migration and
stratigraphic expression
http://walrus.wr.usgs.gov/seds/bedforms/index.html