CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > FLUENT

Compressible flow solver in Fluent

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

Reply
 
LinkBack Thread Tools Display Modes
Old   May 21, 2012, 11:19
Default Compressible flow solver in Fluent
  #1
Member
 
James Willie
Join Date: Mar 2009
Posts: 71
Rep Power: 8
jwillie2000 is on a distinguished road
Hi All,

I have a case where the flow is compressible due a small gap in the geometry where the velocity shuts up, with even the possiblity of a shock wave. It is air and i am wondering whether using the segregated solver with coupled pressure-velocity can do in Fluent? And what about the boundary condition at the inlet? Currently, i am using a velocity inlet but i am not getting the mass balance. The mass at the inlet is exaggerated. Plus using the density solver does not seem to be getting the velocity profile i expect. I know CFX would do a better job but we do not have a cfx license. Just wanted to know your thoughts? U think changing to a pressure inlet boundary would do?

Thanks! Jimmy
jwillie2000 is offline   Reply With Quote

Old   May 22, 2012, 00:54
Default
  #2
Far
Super Moderator
 
Far's Avatar
 
Sijal Ahmed Memon (turboenginner@gmail.com)
Join Date: Mar 2009
Location: Islamabad Pakistan
Posts: 3,916
Blog Entries: 6
Rep Power: 39
Far will become famous soon enoughFar will become famous soon enough
Send a message via Skype™ to Far
Quote:
segregated solver with coupled pressure-velocity can do in Fluent
You can say this is the semi coupled solver as energy equation is solved in segregated manner.

Pressure based coupled solver is good at both incompressible and compressilble flows. So you should go for it.
Far is offline   Reply With Quote

Old   May 22, 2012, 08:11
Default
  #3
Member
 
James Willie
Join Date: Mar 2009
Posts: 71
Rep Power: 8
jwillie2000 is on a distinguished road
Hi Far, and thanks for your input. I am using the segregated solver with coupled velocity-pressure coupling. But the mass balance is not just working. The mass flow at the inlet has increased and that at the outlet is about the value i expect. For spatial discretization i am using the QUICK scheme. Any idea why this may be happpening? Theoretically, i expect the velocity after the duct to shoot up to about 670 m/s, which is quite high. I have a velocity inlet and a pressure outlet. Will be nice if you can comment. Thanks!

Jimmy
jwillie2000 is offline   Reply With Quote

Old   May 22, 2012, 10:35
Default
  #4
New Member
 
Join Date: May 2012
Posts: 9
Rep Power: 5
clgs.1903 is on a distinguished road
Hi Jimmy,

The documentation states that velocity inlets should not be used for compressible flow, and to use mass flow inlets instead.

http://hpce.iitm.ac.in/website/Manua...ug/node222.htm

I was having a similar issue until I found this bit of information. Hope this helped!
clgs.1903 is offline   Reply With Quote

Old   May 25, 2012, 09:58
Default
  #5
Member
 
James Willie
Join Date: Mar 2009
Posts: 71
Rep Power: 8
jwillie2000 is on a distinguished road
Hi Far,
Thanks for your input. I have it now with mass flow inlet and it is converging and the mass balance is kind of okay but only after running for long time. The question is with the energy equation. The residuals for temp keep fluctuating. They drop and then increase and yesterday for example i had a sudden jump and the solver crashed. I lower the under-relaxation factors and it is runnig again but has just starting going up again after being stable for a long time. The under-relaxation factor for the temp is now at 0.8. Have you had a similar problem?
Thanks! Jimmy
jwillie2000 is offline   Reply With Quote

Reply

Thread Tools
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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
SteadyState solver for compressible flow matteo_gautero OpenFOAM Running, Solving & CFD 32 November 21, 2012 05:27
solver for subsonic compressible turbulent flow in OF 1.7 nileshjrane OpenFOAM Running, Solving & CFD 20 February 13, 2012 06:54
compressible flow solver in OF1.6 mecbe2002 OpenFOAM 9 December 25, 2010 10:17
Natural Convection using Compressible Flow (chtMultiRegionFOAM) msarkar OpenFOAM 2 September 7, 2010 00:13
Can segregated solver be used for compressible flow? Steven-GY ANSYS 0 May 14, 2009 10:37


All times are GMT -4. The time now is 00:50.