# Divergence and High Aspect Ratios

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April 6, 2013, 17:16
#41
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Quote:
 Originally Posted by Far Because refined mesh is capturing some unsteady flow phenomena which was not being captured in coarse mesh.
I thought the same thing.

I was wondering what value should I be taking for the pressure and velocity? average values?My pressure values are varying from 99200+450.

Also, how do we say it is mesh independent solution? My previous mesh did not have this big oscillation. The pressure was varying from 99010+50.

So, this can be considered mesh independent solution?Also, if my next mesh refinement oscillates more, what mesh I should be taking as final?

Last edited by victoryv; April 7, 2013 at 09:44.

April 7, 2013, 13:55
#42
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Ali
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Quote:
 Originally Posted by victoryv I thought the same thing. My pressure values are varying from 99200+450. The pressure was varying from 99010+50.
What are the units of pressure? If in "Pa", then you have to look into youe mesh, solution. Something gone wrong.
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Ali

April 7, 2013, 14:11
#43
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Quote:
 Originally Posted by Hybrid What are the units of pressure? If in "Pa", then you have to look into youe mesh, solution. Something gone wrong.
Yes the units are in pascal. Why is it wrong?

 April 9, 2013, 15:27 #44 Member   Join Date: Sep 2012 Location: FL Posts: 76 Rep Power: 4 Can someone suggest me ?

 April 10, 2013, 11:30 #45 Senior Member   Ali Join Date: Jan 2012 Location: Pakistan Posts: 111 Rep Power: 7 Looks too big number, whats your boundary conditions at inlet. is there any possibility to share your mesh or case files? __________________ Best Regards Ali

April 10, 2013, 14:01
#46
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Quote:
 Originally Posted by Hybrid Looks too big number, whats your boundary conditions at inlet. is there any possibility to share your mesh or case files?
Boundary conditions are fine. Sen you a mail.

P.S I am monitoring pressure and velocity values at a point

 April 13, 2013, 14:21 #47 Super Moderator     Sijal Ahmed Memon (turboenginner@gmail.com) Join Date: Mar 2009 Location: Islamabad Pakistan Posts: 3,971 Blog Entries: 6 Rep Power: 39 what are the boundary conditions at inlet and outlet

 April 14, 2013, 05:38 #48 Super Moderator     Sijal Ahmed Memon (turboenginner@gmail.com) Join Date: Mar 2009 Location: Islamabad Pakistan Posts: 3,971 Blog Entries: 6 Rep Power: 39 done meshing and solution. Results seem ok and maximum velocity is 70 m/sec 1. Mesh scaled by 0.001 in all directions. 2. Pressure inlet and pressure outlet were used with given boundary conditions 3. Pressure based coupled solver. 4. 2nd order unwind for convection terms 5. pseudo transient and high order term relaxation used 6. Y+ is less than 6 and therefore qualifies for integration to wall approach along with SST turbulence model. 7. Flow is assumed to be incompressible (need confirmation) Enjoy... victoryv likes this.

 April 14, 2013, 06:19 #49 Super Moderator     Sijal Ahmed Memon (turboenginner@gmail.com) Join Date: Mar 2009 Location: Islamabad Pakistan Posts: 3,971 Blog Entries: 6 Rep Power: 39

 April 14, 2013, 12:54 #50 Member   Join Date: Sep 2012 Location: FL Posts: 76 Rep Power: 4 Hi Far, Thank you so much. The results seem to be good. 1. Why did you scale the mesh? 2. I have compressible results to compare with. So I am doing compressible flow. 3.What is this "higher order relaxation" you used? 4.My target is y+<1(or ~1). Also what do you mean by " integration to wall approach" ? 5. Also, by how many lengths did you extend the domain?

 April 14, 2013, 20:00 Mesh #51 Super Moderator     Sijal Ahmed Memon (turboenginner@gmail.com) Join Date: Mar 2009 Location: Islamabad Pakistan Posts: 3,971 Blog Entries: 6 Rep Power: 39

 April 14, 2013, 20:09 #52 Member   Join Date: Sep 2012 Location: FL Posts: 76 Rep Power: 4 I am not able to download the file. Also, can you please email me the file or link instead of uploading here and yeah can you please answer the questions I have asked earlier.

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