Moving water, Flowing water, Help Please.

I am needing a water the flows around objects. Like if i have a river and put a big rock in the center if would flow around it. Is there any tutorials or scripts that any one know that would help me in starting this?

i use this Asset:
FLOW

it has a free version too:
FLOW free

i bought it some days ago and learned it really fast - it´s really easy and creates very good flow effects. With some particles on the place where water hits obstacles, it looks amazing!

Ok thanks I will have a look at it.