CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > CFX

Curved flow

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   December 25, 2013, 22:08
Default Curved flow
  #1
Senior Member
 
Govindaraju
Join Date: Apr 2010
Posts: 209
Rep Power: 16
kmgraju is on a distinguished road
Dear all
My geometry has a curved pipe. the fluid entering +y direction (inlet as pressure). The outlet axis coordinate has (+x,-y) coordinate. So I introduced outlet (velocity) as Normal to the surface.

My question is if I rotate the component in the workbench so that the outlet is along X axis, How about my result in this case and previous case? is it same or different?

Thank you

Govind
kmgraju is offline   Reply With Quote

Old   December 26, 2013, 00:13
Default
  #2
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,665
Rep Power: 143
ghorrocks is just really niceghorrocks is just really niceghorrocks is just really niceghorrocks is just really nice
If you rotate the thing and do the same simulation you should expect the same result, just rotated. Is that what you are asking?

Or are you asking if you can use a previous rotated simulation as an initial condition? That is harder - in general, no, you cannot.
ghorrocks is offline   Reply With Quote

Old   December 26, 2013, 05:31
Default
  #3
Senior Member
 
Govindaraju
Join Date: Apr 2010
Posts: 209
Rep Power: 16
kmgraju is on a distinguished road
Quote:
Originally Posted by ghorrocks View Post
If you rotate the thing and do the same simulation you should expect the same result, just rotated. Is that what you are asking?

Or are you asking if you can use a previous rotated simulation as an initial condition? That is harder - in general, no, you cannot.
Thank you Very much
I have another question. Please find the attached pictures. I am confusing about turbulence model.I run the steady state first and then transient . My inlet is pressure and outlet is velocity . I am expecting low Reynolds turbulence occurring near the curve and the area restriction . Is my solution is converged or not.I tried SST model .I also tried tried many models like RNG K-epsilon, K-omega etc , but the solution doesn't meet the convergence criteria 10^-4
Give your advice
Thank you
Govind
Attached Images
File Type: png 3.png (45.6 KB, 7 views)
File Type: png 4.png (27.0 KB, 7 views)
File Type: png 2.png (11.1 KB, 5 views)
File Type: png 1.png (14.6 KB, 5 views)
kmgraju is offline   Reply With Quote

Old   December 26, 2013, 05:46
Default
  #4
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,665
Rep Power: 143
ghorrocks is just really niceghorrocks is just really niceghorrocks is just really niceghorrocks is just really nice
FAQ: http://www.cfd-online.com/Wiki/Ansys...gence_criteria
ghorrocks is offline   Reply With Quote

Old   December 26, 2013, 10:36
Default
  #5
Senior Member
 
Govindaraju
Join Date: Apr 2010
Posts: 209
Rep Power: 16
kmgraju is on a distinguished road
Quote:
Originally Posted by ghorrocks View Post
Dear all
please find the following statement.U Mom, v-mom, Vmom, P-mass all are F.
This will start from 70th iteration t0 100 iteration . what does it mean.

Thank you

+----------------------+------+---------+---------+------------------+
| U-Mom | 1.00 | 3.8E-04 | 9.5E-03 | 1.0E+00 F |
| V-Mom | 1.00 | 3.8E-04 | 7.5E-03 | 1.0E+00 F |
| W-Mom | 1.00 | 5.2E-04 | 1.7E-02 | 1.0E+00 F |
| P-Mass | 1.00 | 1.0E-04 | 5.4E-03 | 8.9 1.0E+00 F |
+----------------------+------+---------+---------+------------------+
| K-TurbKE | 0.99 | 8.7E-05 | 4.4E-03 | 5.7 8.1E-02 OK|
| O-TurbFreq | 1.05 | 8.3E-06 | 8.6E-04 | 10.5 5.8E-07 OK|
+----------------------+------+---------+---------+------------------+
| Rethetat | 2.17 | 6.1E-04 | 2.8E-01 | 5.9 1.0E-02 OK|
| Intermit | 0.77 | 6.0E-05 | 1.4E-02 | 5.7 5.8E-03 OK|
+----------------------+------+---------+---------+------------------+

================================================== ====================
OUTER LOOP ITERATION = 88 CPU SECONDS = 2.320E+03
----------------------------------------------------------------------
| Equation | Rate | RMS Res | Max Res | Linear Solution |
+----------------------+------+---------+---------+------------------+
| U-Mom | 1.00 | 3.8E-04 | 9.5E-03 | 1.0E+00 F |
| V-Mom | 1.00 | 3.8E-04 | 7.5E-03 | 1.0E+00 F |
| W-Mom | 1.00 | 5.2E-04 | 1.7E-02 | 1.0E+00 F |
| P-Mass | 1.00 | 1.0E-04 | 5.4E-03 | 8.9 1.0E+00 F |
+----------------------+------+---------+---------+------------------+
| K-TurbKE | 0.99 | 8.6E-05 | 4.3E-03 | 5.7 8.0E-02 OK|
| O-TurbFreq | 1.03 | 8.6E-06 | 9.1E-04 | 10.5 5.3E-07 OK|
+----------------------+------+---------+---------+------------------+
| Rethetat | 1.16 | 7.1E-04 | 2.6E-01 | 5.9 1.1E-02 OK|
| Intermit | 1.06 | 6.4E-05 | 8.7E-03 | 5.7 7.1E-03 OK|
+----------------------+------+---------+---------+------------------+
kmgraju is offline   Reply With Quote

Old   December 27, 2013, 05:34
Default
  #6
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,665
Rep Power: 143
ghorrocks is just really niceghorrocks is just really niceghorrocks is just really niceghorrocks is just really nice
This is explained in the documentation. It means the linear solver is diverging. Check that your simulation is correctly setup, improve your mesh quality, use smaller time steps, double precision numerics or a better initial condition.
ghorrocks is offline   Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
transient, impregnating flow problem fgommer FLUENT 0 February 29, 2012 17:10
Non-steady flow simplified for use in Vissim steamerandy Main CFD Forum 0 October 31, 2011 22:08
Fully Developed Flow in Star-cd SMM STAR-CD 0 September 5, 2011 23:08
Flow meter Design CD adapco Group Marketing Siemens 3 June 21, 2011 09:33
transform navier-stokes eq. to euler-eq. pxyz Main CFD Forum 37 July 7, 2006 09:42


All times are GMT -4. The time now is 08:46.