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

Compressible flow modeling in Fluent

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   August 8, 2011, 13:35
Default Compressible flow modeling in Fluent
  #1
New Member
 
Nik
Join Date: Mar 2010
Location: Michigan
Posts: 25
Rep Power: 16
nikhil is on a distinguished road
Hello,

I have few questions on compressible flow modeling in Fluent

1. Can i use velocity inlet and pressure outlet BCs while modeling compressible flow?

2. Can i use pressure based solver to model the compressible flow?

3. I am using velocity inlet, pressure outlet in one of my cases and pressure based solver. However, when i initialize the solution, i am getting this error message

Error:
FLUENT received fatal signal (ACCESS_VIOLATION)
1. Note exact events leading to error.
2. Save case/data under new name.
3. Exit program and restart to continue.
4. Report error to your distributor.
Error Object: #f


can anyone please explain why am i getting such error message and how to overcome it?

Thanks,
Nikhil
nikhil is offline   Reply With Quote

Old   August 8, 2011, 13:55
Default
  #2
New Member
 
Pavel Staša
Join Date: Apr 2010
Location: Czech Republic
Posts: 9
Rep Power: 16
Pavlos is on a distinguished road
For questions one and two my answer is YES.
For last one, my oppinion is that mesh might be wrong or type of other BC are wrong.

If I´m wrong, correct me.
Pavlos is offline   Reply With Quote

Old   August 8, 2011, 14:16
Default
  #3
New Member
 
Nik
Join Date: Mar 2010
Location: Michigan
Posts: 25
Rep Power: 16
nikhil is on a distinguished road
Mesh is pretty much simple and without any error.
Its a 2D domain. Therefore apart from inlet and outlet; other two boundaries are walls which are fine from my consideration.
nikhil is offline   Reply With Quote

Old   August 8, 2011, 16:55
Default
  #4
New Member
 
Vijay
Join Date: Mar 2009
Posts: 21
Rep Power: 17
Vijay is on a distinguished road
You cannot have velocity and pressure boundary condiitons in a single domain...I guess
Vijay is offline   Reply With Quote

Old   August 9, 2011, 05:24
Default
  #5
New Member
 
Pavel Staša
Join Date: Apr 2010
Location: Czech Republic
Posts: 9
Rep Power: 16
Pavlos is on a distinguished road
My apology. I really thought that velocity inlet can be used for compressible flow but there is a explanation in Fluent manual.

Velocity inlet BC:
"This boundary condition is intended for incompressible flows, and its use in compressible flows will lead to a nonphysical result because it allows stagnation conditions to float to any level. You should also be careful not to place a velocity inlet too close to a solid obstruction, since this could cause the inflow stagnation properties to become highly non-uniform."
Pavlos is offline   Reply With Quote

Old   August 9, 2011, 05:30
Default
  #6
New Member
 
Pavel Staša
Join Date: Apr 2010
Location: Czech Republic
Posts: 9
Rep Power: 16
Pavlos is on a distinguished road
Quote:
Originally Posted by Vijay View Post
You cannot have velocity and pressure boundary condiitons in a single domain...I guess
You can easily use velocity and pressure BC in a single domain. There is no problem.


You can use three combinations of BC at the inlet and outlet.
1. Velocity inlet - Outflow
2. Velocity inlet - Pressure outlet
3. Pressure inlet - Pressure outlet


Instead of velocity inlet you can use mass flow inlet too, of course.
Pavlos is offline   Reply With Quote

Old   August 9, 2011, 08:07
Default
  #7
New Member
 
Karl Kargl
Join Date: Mar 2009
Location: Austria
Posts: 9
Rep Power: 17
Karl is on a distinguished road
For compressible flows only two combinations are valid:

1. Mass Flow Inlet + Pressure Outlet
2. Pressure Inlet + Pressure Outlet

Velocity Inlet and Outflow are incorrect BC's for modeling compressible flows with FLUENT.

Best Regards
Karl is offline   Reply With Quote

Old   August 9, 2011, 09:57
Default
  #8
New Member
 
Pavel Staša
Join Date: Apr 2010
Location: Czech Republic
Posts: 9
Rep Power: 16
Pavlos is on a distinguished road
Quote:
Originally Posted by Karl View Post
For compressible flows only two combinations are valid:

1. Mass Flow Inlet + Pressure Outlet
2. Pressure Inlet + Pressure Outlet

Velocity Inlet and Outflow are incorrect BC's for modeling compressible flows with FLUENT.

Best Regards

Of course, I mean generally you can use velocity inlet and Outflow, not for case of combressible flows.

Velocity Inlet is incorrect and Outflow is incorrect too for compressible flows.
Pavlos is offline   Reply With Quote

Old   August 9, 2011, 15:18
Default
  #9
New Member
 
Nik
Join Date: Mar 2010
Location: Michigan
Posts: 25
Rep Power: 16
nikhil is on a distinguished road
Thanks all...

With mass flow inlet and pressure outlet my case is running smoothly.
nikhil 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
Viscoelastic flow modeling in Fluent Ankur Navra FLUENT 3 July 26, 2013 06:56
Natural Convection using Compressible Flow (chtMultiRegionFOAM) msarkar OpenFOAM 2 September 7, 2010 01:13
help with compressible flow BC's (need subsonic flow) meangreen Main CFD Forum 5 July 24, 2010 14:16
compressible flow maria teresa FLUENT 1 September 7, 2007 17:58
Solving unsteady compressible low speed flow atit Main CFD Forum 8 July 31, 2000 14:19


All times are GMT -4. The time now is 20:26.