Zig Zag Streamlines

aakash hassan · June 23, 2016, 07:55

Hello everyone, I am studying flow of air inside solar chimney. Streamlines show irregular pattern of flow but velocity is still high. Does this mean that there is turbulence in flow and mass flow rate has decreased because all the streamlines are not flowing through the chimney? I've attached image file so can get idea. Any suggestion will be appreciated.

-Maxim- · June 24, 2016, 09:57

it looks like they bounce of that intersection plane. My guess is that you haven't set up the configuration correctly since you probably want to get the result for a 360° chimney. How did you define your boundary conditions/walls?
Please share your out-file.

aakash hassan · June 25, 2016, 03:42

Thanks a lot Maxim for your reply. I think this bounce isn't due to intersection plane because streamlines show a smooth flow at small slope. These are results when collector slope is increased.

ghorrocks · June 25, 2016, 04:58

This looks like it has not converged fully yet

aakash hassan · June 25, 2016, 10:21

Thanks Ghorrocks for reply, Actually solution got converged when i used first order accuracy,but for 2nd order, residuals showed problem in converging and didn't fell upto converging criteria. But residuals got stable after 1500 iterations, and solution was not changing much with successive iterations. And continuity residual approached almost 1e-3 and energy reached below 1e-6. So i assumed that solution has converged.

ghorrocks · June 25, 2016, 21:54

You can't assume that! Read the FAQ: http://www.cfd-online.com/Wiki/Ansys...gence_criteria

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June 24, 2016, 09:57		#2
-Maxim- Senior Member Maxim Join Date: Aug 2015 Location: Germany Posts: 413 Rep Power: 13	it looks like they bounce of that intersection plane. My guess is that you haven't set up the configuration correctly since you probably want to get the result for a 360° chimney. How did you define your boundary conditions/walls? Please share your out-file.

June 25, 2016, 03:42		#3
aakash hassan New Member aakash Join Date: Feb 2016 Posts: 6 Rep Power: 10	Thanks a lot Maxim for your reply. I think this bounce isn't due to intersection plane because streamlines show a smooth flow at small slope. These are results when collector slope is increased.

June 25, 2016, 04:58		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	This looks like it has not converged fully yet

June 25, 2016, 10:21		#5
aakash hassan New Member aakash Join Date: Feb 2016 Posts: 6 Rep Power: 10	Thanks Ghorrocks for reply, Actually solution got converged when i used first order accuracy,but for 2nd order, residuals showed problem in converging and didn't fell upto converging criteria. But residuals got stable after 1500 iterations, and solution was not changing much with successive iterations. And continuity residual approached almost 1e-3 and energy reached below 1e-6. So i assumed that solution has converged.

June 25, 2016, 21:54		#6
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	You can't assume that! Read the FAQ: http://www.cfd-online.com/Wiki/Ansys...gence_criteria