Flow separation in diffuser section of a wind tunnel
 

Dear openFoamers!

Greetings. I want to simulate flow separation in a diffuser section of a wind tunnel. Based on my experimental result, the flow domain is as follows:

http://i62.tinypic.com/15qra0m.jpg

Actually I have modified the pitzDaily tutorial of openFoam. From experiment: the inlet velocity is 4m/s. Inlet height is 200mm and straight section length is 630mm. The diffuser angle is 20deg. Assuming 5% fluctuation of U at inlet: k=0.06 and epsilon=0.0911 with other parameter unchanged.

After running the solver, the expected separation was absent in diffuser section.
http://www.mediafire.com/watch/6s1auqgpz26nilt/3.avi

What should I do to get expected separation in diffuser section?

Best regards,
mukut

What size of separation region do you expect? The outlet of your domain looks pretty close to the separation point. Maybe it is close enough to damp down the whole separation?