|
[Sponsors] |
July 15, 2013, 06:49 |
'Air Ideal gas' density problem
|
#1 |
New Member
Rameez
Join Date: May 2013
Posts: 19
Rep Power: 13 |
I had run a simulation of a stator-rotor combination, for which I had chosen the medium as Air Ideal Gas. After the simulations were done, when i generated report, i was surprised to see the considered density to be 2.23 kg/m-3. Shouldn't it have been 1.2256 kg/m-3? Also how do i rectify it to make it as 1.2256 kg/m-3
|
|
July 15, 2013, 21:31 |
|
#2 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,870
Rep Power: 144 |
This looks like an error in your reference pressure. If the reference pressure is 1atm and you have a pressure of 1atm then you have 2atm absolute and densities about 2.2kg/m3.
|
|
July 16, 2013, 00:34 |
|
#3 |
New Member
Rameez
Join Date: May 2013
Posts: 19
Rep Power: 13 |
Thanks a lot for your valuable reply. Could you please respond to the following questions too.
Should i take the reference pressure as 0 atm? So now do i have to re run the simulations? And how do i rectify it? |
|
July 16, 2013, 00:45 |
|
#4 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,870
Rep Power: 144 |
You should put the reference pressure as a typical pressure in your domain. The documentation explains this.
And yes, you will have to redo the simulation as your current results are wrong. |
|
July 16, 2013, 01:24 |
|
#5 |
New Member
Rameez
Join Date: May 2013
Posts: 19
Rep Power: 13 |
Thanks again. I would like to explain my problem definition-
I had specified the reference pressure as 1 atm Boundary condition: mass flow inlet to static pressure outlet So accordingly i plugged in the values as Inlet: Normal speed as 8.49 m/s Outlet: 1 atm as my turbomachine opens into atmosphere. So to rectify the problem of density, should i change the reference pressure as 0 atm or the outlet pressure as 0 atm or some other changes should be done. |
|
July 16, 2013, 06:51 |
|
#6 |
Senior Member
Erik
Join Date: Feb 2011
Location: Earth (Land portion)
Posts: 1,188
Rep Power: 23 |
Outlet pressure should be zero, reference pressure should be 1 atm.
Either will work fine, as long at they add up to 1atm, but this way is better for round off errors and things of that nature. |
|
July 16, 2013, 13:45 |
|
#7 |
New Member
Rameez
Join Date: May 2013
Posts: 19
Rep Power: 13 |
Thanks for your help.
|
|
Tags |
density |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
a problem of incompressible two phases(water and gas) with VOF Method | zhangweisnoopy | Main CFD Forum | 9 | August 12, 2011 09:25 |
source term in a gas mixture problem | Kevin | Siemens | 0 | March 27, 2008 06:55 |
Two-Phase Buoyant Flow Issue | Miguel Baritto | CFX | 4 | August 31, 2006 13:02 |
Problem using ideal gas | mark | FLUENT | 3 | November 29, 2004 17:40 |
Warning 097- | AB | Siemens | 6 | November 15, 2004 05:41 |