# Total mass flow

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 November 22, 2010, 10:23 Total mass flow #1 New Member   Enio Carpi Join Date: Apr 2010 Posts: 12 Rep Power: 14 Hi Folks I'm simulating a chamber pumpdown using a getter. The pumpdown speed depends on the total mass sorbed by the getter (I have the model for that). What would be the variable for the cumulative mass flow through an outlet? Or would it be possible to integrate over time? thx for the help

 November 22, 2010, 16:00 #2 Member   Join Date: Feb 2010 Location: Australia Posts: 65 Rep Power: 15 You could do a numerical integration via a CEL expression. Not sure on the variable though - I have no knowledge in this area.

 November 22, 2010, 17:29 #3 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,326 Rep Power: 138 Sorry, but no. You cannot do time integrals in CEL. If you have to do time integrals you will need to do it in fortran.

 November 22, 2010, 17:57 #4 Member   Join Date: Feb 2010 Location: Australia Posts: 65 Rep Power: 15 So CFX does not have an internal time value that can be used/addressed?

 November 22, 2010, 18:10 #5 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,326 Rep Power: 138 Yes, CFX does have a time value. But CEL values do not persist between time steps so there is no way to accumulate over time. You could make a fortran CEL function to do the accumulation over time and normal CEL to do everything else. This is not too hard to do.

 November 23, 2010, 05:41 #6 New Member   Enio Carpi Join Date: Apr 2010 Posts: 12 Rep Power: 14 Thanks for the comments. So, it seems I'm stuck here. I'll work on something. Thank you again

 November 24, 2010, 11:59 #7 New Member   Enio Carpi Join Date: Apr 2010 Posts: 12 Rep Power: 14 So fa rthe only solution is to use "mass()@domain". The total mass out of the domain is initial mass - mass()@domain. It seems to work. Now I just need the folks from SAES to send me some data. Take care

 Tags cfx, getter