CFD Online Logo CFD Online URL
Home > Forums > OpenFOAM Running, Solving & CFD

Total specie mass instead of local concentration

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

LinkBack Thread Tools Display Modes
Old   May 12, 2006, 03:09
Default The output files of combustion
Tomislav Sencic
Join Date: Mar 2009
Posts: 42
Rep Power: 10
tsencic is on a distinguished road
The output files of combustion/chemistry solvers, beside others, are species concentrations (O2, N2, CO2, CO...), with a list of local concentration in each cell. The problem is that bigger cells contribute to the global concentration more than the small ones, so just calculating the average does not lead to the correct result. In addition, in engine solvers cell volume changes with time. How can be obtained the average concentration over the hole domain? Or, how could I output specie mass instead of concentration? Where can I find the cell volumes?
tsencic is offline   Reply With Quote

Old   May 12, 2006, 03:35
Default The cell volumes are available
Assistant Moderator
Bernhard Gschaider
Join Date: Mar 2009
Posts: 4,034
Rep Power: 43
gschaider will become famous soon enoughgschaider will become famous soon enough
The cell volumes are available via mesh.V() (Look at table 2.1 in the Programmers guide; it's small but most useful).

Average concentration would be

Note: I don't use "Friend"-feature on this forum out of principle. Ah. And by the way: I'm not on Facebook either. So don't be offended if I don't accept your invitation/friend request
gschaider is offline   Reply With Quote

Old   May 12, 2006, 03:37
Default the solvers write out the spec
Join Date: Mar 2009
Posts: 96
Rep Power: 10
stefanke is on a distinguished road
the solvers write out the species mass fraction of each cell. If you want to know the global mass of a specie just sum up the specie mass fraction of each cell you will get the right result:

mathematical writing:

m_k_tot = Sum_j(m_kj) = Sum_j(rho_j*Y_kj*V_j)

k is the species index
j is the cell index


You can get the cell volumes from 'mesh.V()'
stefanke is offline   Reply With Quote


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
mass concentration kim FLUENT 0 August 25, 2008 12:32
mass concentration kim Main CFD Forum 0 August 25, 2008 03:11
Mass Concentration Jaloha CFX 0 June 17, 2008 10:47
How to get specie mass fraction at a boundary face shuqin FLUENT 0 February 24, 2006 02:52
concentration, total mass?? yee wan FLUENT 0 February 24, 2003 22:34

All times are GMT -4. The time now is 01:16.