swirling_eddy__clackamas_river__oregon-1_400x300

An eddy is a swirling of a fluid

and the reverse current created

when the fluid flows past an obstacle.

 

I am a rock . . .

 

The moving fluid

creates a space devoid

of downstream-flowing fluid

on the downstream side of the object.

 

I am an island . .

 

Fluid behind the obstacle flows into the void

creating a swirl of fluid

on each edge of the obstacle

followed by a short reverse flow

of fluid behind the obstacle

flowing upstream

toward the back of the obstacle.

 

And a rock feels no pain . . .

 

This phenomenon

is most visible

behind

large

emergent

rocks

in

swift-flowing rivers.

 

And an island never cries . . .

 

Image source: http://www.thebrwa.org/enewsletters/eNews_2013/BRWA_Newsletter_0213.html

Text source: verbatim from Wikipedia and Paul Simon lyrics from “I am a Rock”