# Species mass flow rate

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

 April 19, 2011, 15:03 Species mass flow rate #1 Member   N. A. Join Date: May 2010 Posts: 64 Rep Power: 9 Sponsored Links Hello All, I am trying to calculate the average mass flow rate of a particular species passing through a plane in the geometry, such as mass flow rate of CO2 passing through a plane. Can you please let me know if know how we can extract this information in paraview. Is there a way to calcualte this value directly in OpenFOAM Thanks, Nir

 November 14, 2012, 19:16 #2 Super Moderator     Tobias Holzmann Join Date: Oct 2010 Location: Leoben (Austria) Posts: 1,835 Blog Entries: 6 Rep Power: 32 Hi, your post is old and you just made four posts so I think none will answer me. Do you find out how that works? If someone can explain it, it would be very good for me and all the others Tobi

 November 15, 2012, 05:16 #3 Senior Member   Tom Fahner Join Date: Mar 2009 Location: Delft, Netherlands Posts: 370 Rep Power: 14 Hello Tobi, How are you? I think I may be able to help you on this one. The most easy way to do this with paraView would be to calculate the total mass flow through a plane using Y_CO2*rho*U_n where U_n is the velocity component normal to the plane of interest and Y_CO2 is the mass fraction of CO2. If you have a plane not aligned with x, y or z, you can use the calculator filter or the surface flow filter to get the velocity components perpendicular to that plane. Make sure the calculator for rho*U_n works on the cell data. Than go to filters>integrate Variables and you will get a table with the integral Y_CO2*rho*U*dA over Area A. This is the mass of CO2 passing through the area. I do not have an example for doing this during the calculation, but I think something can be done with swak4Foam. Regards, Tom kostnermo likes this.

November 15, 2012, 12:48
#4
Super Moderator

Tobias Holzmann
Join Date: Oct 2010
Location: Leoben (Austria)
Posts: 1,835
Blog Entries: 6
Rep Power: 32
Quote:
 Originally Posted by tomf Hello Tobi, How are you? I think I may be able to help you on this one. The most easy way to do this with paraView would be to calculate the total mass flow through a plane using Y_CO2*rho*U_n where U_n is the velocity component normal to the plane of interest and Y_CO2 is the mass fraction of CO2. If you have a plane not aligned with x, y or z, you can use the calculator filter or the surface flow filter to get the velocity components perpendicular to that plane. Make sure the calculator for rho*U_n works on the cell data. Than go to filters>integrate Variables and you will get a table with the integral Y_CO2*rho*U*dA over Area A. This is the mass of CO2 passing through the area. I do not have an example for doing this during the calculation, but I think something can be done with swak4Foam. Regards, Tom
Hi Tom,

I am fine. I have two weeks left to finish my masterthesis. Did you follow the libOpenSmoke thread? I find some fatal bugs in the tool and will bring out my updated model after I finished my thesis. So I think in 4 Weeks everything is avaiable (maybe + validation and description). To tool is very nice but there are some problems with the enthalpie. But I solved it

Thanks for your replay. I am too stupid
But I test it in the thermolibrary. therefor I ll create a new scalarField and will calculate the CO-emission in PPM directly. I think it should be possible and then I can compare it.

Tobi

November 16, 2012, 04:32
#5
Senior Member

Tom Fahner
Join Date: Mar 2009
Location: Delft, Netherlands
Posts: 370
Rep Power: 14
Hi Tobi,

Yes I did follow the libOpenSmoke thread, looks like you have some interesting results!

Quote:
 But I test it in the thermolibrary. therefor I ll create a new scalarField and will calculate the CO-emission in PPM directly. I think it should be possible and then I can compare it.
Sounds like a plan,

good luck
Tom

 November 16, 2012, 07:46 #6 Super Moderator     Tobias Holzmann Join Date: Oct 2010 Location: Leoben (Austria) Posts: 1,835 Blog Entries: 6 Rep Power: 32 Hi Tom, one question to you. If I want the massweighted species in the whole fluid domain, is it possible to do like you said with mag(U) then?

 November 16, 2012, 10:54 #7 Super Moderator     Tobias Holzmann Join Date: Oct 2010 Location: Leoben (Austria) Posts: 1,835 Blog Entries: 6 Rep Power: 32 Hi Tom, just one question, if I make everything correct. I wanna calculate CO in ppm on a patch. Therefor I calculate the Mean molmass with: M_aver = sum(Y_i / M_i) of CO, O2, H2O, N2, CO2, H2, OH After that I calculate CO in ppm like: COppm = M_aver/M_CO * Y_CO * 1.000.000 Well the temperature profil looks better with OpenFOAM compared with ansys but if I look to the CO emissions there is so a huge difference: Measurement 80 ppm Ansys 60 ppm OF 0.0013 ppm I am not sure if I make everything correct!

November 19, 2012, 06:53
#8
Senior Member

Tom Fahner
Join Date: Mar 2009
Location: Delft, Netherlands
Posts: 370
Rep Power: 14
Quote:
 Originally Posted by Tobi Hi Tom, just one question, if I make everything correct. I wanna calculate CO in ppm on a patch. Therefor I calculate the Mean molmass with: M_aver = sum(Y_i / M_i) of CO, O2, H2O, N2, CO2, H2, OH After that I calculate CO in ppm like: COppm = M_aver/M_CO * Y_CO * 1.000.000 Well the temperature profil looks better with OpenFOAM compared with ansys but if I look to the CO emissions there is so a huge difference: Measurement 80 ppm Ansys 60 ppm OF 0.0013 ppm I am not sure if I make everything correct!
Hi Tobi,

I would think you have:

M_aver = sum(Y_i * M_i)/sum (Y_i) = sum(Y_i * M_i)

and I agree with your calculation of COppm.
Regards,
Tom

Last edited by tomf; November 19, 2012 at 06:54. Reason: typo

November 19, 2012, 08:11
#9
Super Moderator

Tobias Holzmann
Join Date: Oct 2010
Location: Leoben (Austria)
Posts: 1,835
Blog Entries: 6
Rep Power: 32
Quote:
 Originally Posted by tomf Hi Tobi, I would think you have: M_aver = sum(Y_i * M_i)/sum (Y_i) = sum(Y_i * M_i) and I agree with your calculation of COppm. Regards, Tom
Hi Tom,

I made a validation of my COppm calculation like I mentioned in the last post and its correct, like you told me

In that case I realized a other bug in the thermodynamics
but in my thesis there is no time for it. Maybe its a problem with the flameletgeneration.

Tobi

 December 3, 2012, 18:45 #10 Senior Member   Wouter van der Meer Join Date: May 2009 Location: Elahuizen, Netherlands Posts: 185 Rep Power: 10 Hello, Maybe a stupid thing to ask someone that is working on a thesis, but is ppm for gasses not volume based instead of mass based? best regards Wouter

December 3, 2012, 19:29
#11
Super Moderator

Tobias Holzmann
Join Date: Oct 2010
Location: Leoben (Austria)
Posts: 1,835
Blog Entries: 6
Rep Power: 32
Quote:
 Originally Posted by wouter Hello, Maybe a stupid thing to ask someone that is working on a thesis, but is ppm for gasses not volume based instead of mass based? best regards Wouter
Hi,

ppm on (maybe) the species CO is based on the mol fraction [X_CO] * 1.000.000 = CO_ppm.

If you wanna get an information on a slice its better to make a mass weighted calculation to get the better result.

If you wanna get an information on a specified volume you should do a volume weighted calculation.

If I am wrong please correct me.

Greetings Tobi

January 20, 2016, 13:03
#12
Member

Thomas Oliveira
Join Date: Apr 2015
Posts: 92
Rep Power: 4
Quote:
 Originally Posted by N. A. calculate the average mass flow rate of a particular species passing through a plane in the geometry [...] Is there a way to calculate this value directly in OpenFOAM
I had a similar problem (integrate a variable over an internal plane) and managed to do so. Please refer to http://www.cfd-online.com/Forums/ope...tml#post581774 . You may have to use areaNormalAverage instead of areaNormalIntegrate.

Best wishes,

Thomas

 Thread Tools Display Modes Linear Mode

 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 OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post eddie FLUENT 15 July 19, 2017 09:31 wildli FLUENT 2 July 8, 2015 11:38 sanchezz CFX 2 January 14, 2010 07:54 Masood FLUENT 0 May 22, 2005 00:32 Wang Xin Phoenics 2 May 10, 2003 02:30