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

why absolute pressure and temperature limited to 1.000000e+00?

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

Reply
 
LinkBack Thread Tools Display Modes
Old   January 27, 2010, 15:51
Default why absolute pressure and temperature limited to 1.000000e+00?
  #1
New Member
 
wild
Join Date: Dec 2009
Posts: 11
Rep Power: 6
wildli is on a distinguished road
Dear all,
I am running a case of two counter rotating wheel in a chamber(adiabatic) to compress air (ideal gas), I am meeting the problem of absolute pressure and temperature limited to 1.00000e+00 for a lot of cells. Whenever I switched the air into constant density but keep energy equation on, there is no problem for the calculation; I checked the fluid characteristics, it looks like both wheels rotate very well, and give me some good result for constant density gas.
The problem lies in solving energy equation.
Can any one give me some hint how to overcome this difficult? it bothers for quite a while, any hint would be highly appreciated.
thanks!

Reference for the settings:
Geometry description starting from the inlet flow:
1. flow inlet --> front chamber flowing zone --> 1st axial impeller(rotating) --> small gap before 2nd wheel --> 2nd wheel(counter rotating) --> back chamber flowing zone --> outlet
2. all of these flowing zone sections have the same out diameter

ANSYS 12-FLUENT
1. Pressure-based, absolute velocity formulation, steady case
2. viscous model selected as standard k-e
3. material selected as idea gas with specific Cp, viscosity
4. fluid inside of two wheels specified as moving reference frame
5. pressure inlet, pressure outlet with static pressure and backflow temperature specified,
6. two impeller wheel are chosen as moving wall which have 0 relative velocity to the adjacent zones.
7. faces between rotating wheel zone and fluid flowing chamber zone are interface
8. simple scheme with least square cell based gradient, and 1st order wind for other parameters
9. URF are set as default
wildli is offline   Reply With Quote

Old   January 28, 2010, 01:25
Default
  #2
mas
New Member
 
Mas
Join Date: Jan 2010
Location: Japan
Posts: 24
Rep Power: 6
mas is on a distinguished road
I'm sure you'll find many answers to that question in this forum if you search. Generally, I think you should increase the quality of your mesh.
__________________
<Mas>
mas 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
temperature limited - absolute pressure limited Asashi FLUENT 3 July 18, 2014 09:51
Calculation of the Governing Equations Mihail CFX 5 July 25, 2008 17:29
Absolute Pressure and temperature limited to...... Shamoon FLUENT 1 August 31, 2007 15:09
pressure and temperature limited Radwa FLUENT 2 July 3, 2006 00:19
what the result is negatif pressure at inlet chong chee nan FLUENT 0 December 29, 2001 05:13


All times are GMT -4. The time now is 07:32.