CFD Online Logo CFD Online URL
Home > Forums > Software User Forums > ANSYS > FLUENT

Validation 12.1 vs 6.3, Difference in Reported Inlet Total Pressure

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

LinkBack Thread Tools Search this Thread Display Modes
Old   April 26, 2011, 05:23
Exclamation Validation 12.1 vs 6.3, Difference in Reported Inlet Total Pressure
jola's Avatar
Jonas Larsson
Join Date: Jan 2009
Location: Gothenburg, Sweden
Posts: 827
Rep Power: 10
jola is on a distinguished road
Send a message via MSN to jola Send a message via Skype™ to jola
We are switching over from Fluent 6.3 to Fluent 12.1 in some of our large design projects. Before doing this we want to validate and compare results obtained with Fluent 12.1 with results previously obtained with Fluent 6.3.

When comparing mass-flow averaged total pressure loss (P0in - P0out)/P0in for an old design we noticed a difference between 6.3 and 12.1. Looking further at this we discovered that the mass-flow average total pressure on the outlet was almost identical, but the inlet value was different! Normally you would expect the opposite - the outlet might be different due to modifications of models/schemes/numerics, but the inlet should be identical!

Looking further at this we tried to make an iso-clip just at the inlet. Computing mass-flow-averaged total pressure on this iso-clip at the inlet gives exactly the same reported total-pressure from Fluent 6.3 and 12.1 (including all decimals)! Hence, Fluent 6.3 and 12.1 uses the set inlet total-pressure boundary condition profile in the same way, but still reports different total pressure on the inlet plane.

My conclusion is that Fluent 6.3 and Fluent 12.1 extrapolates the inlet boundary values differently. If we compute area-averaged values instead the difference is halfed, but it is still there. My interpretation from that is that the error affects both the inlet mass-flow and the inlet total-pressure extrapolation.

Anyone had any similar problems? I am not sure if Fluent 6.3 or Fluent 12.1 reports the correct value. We will have to go back and look at some old validation cases with measurements to judge that and compare results for a more clean case.
jola is online now   Reply With Quote

Old   May 5, 2011, 14:33
Join Date: Jun 2009
Posts: 98
Rep Power: 17
meangreen is on a distinguished road
Hi Jonas,
Thanks for the post. It was nice to read. I did a validation a while ago but I use a jet impacting a particle bed (multiphase flow, turbulent flow). I found that there was not a significant difference.

One thing that has really bothered me is that even with the change from 6.3 to 12.1 none of the problems with the multiphase flow solver were corrected. For example, the solver calculates particles moving too fast along the axisymmetric boundary in version 6.3, this STILL hasn't been fixed.

I think when Ansys bought fluent, they pretty much just slapped a new number on it and added a few extra percs, but I HATE the new gui and refuse to use it.

meangreen is offline   Reply With Quote


12.1, 6.3, inlet, loss, total-pressure, validation

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
total pressure change in a pipe flow Im FLUENT 5 February 23, 2017 08:55
Pressure Inlet Boundary Condition Prasad FLUENT 6 April 9, 2013 21:32
Total Pressure in Laval Nozzle Sohail Ahmed Main CFD Forum 0 May 19, 2004 05:43
Gas pressure question Dan Moskal Main CFD Forum 0 October 24, 2002 22:02
Terrible Mistake In Fluid Dynamics History Abhi Main CFD Forum 12 July 8, 2002 09:11

All times are GMT -4. The time now is 10:40.