# units after multipl. with phi

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 September 26, 2012, 11:01 units after multipl. with phi #1 Senior Member     Tobias Holzmann Join Date: Oct 2010 Location: Leoben (Austria) Posts: 1,506 Blog Entries: 6 Rep Power: 26 Hi all, I have an equation like that: Code: div(phi, H) + Q Solver that is used is rhoSimpleFoam - compressible. The unit of H is [J/kg]. Q has the unit [W/m³]. I had a look at the phi file and the file has the unit [kg/s]. Also I had a look at the createCompressiblePhi.H file and there is phi defined as the mass flow. So after div(phi, H) I should get the unit [J/s] = [W] ... Or am I wrong? If phi = rho then everything would be nice I am a bit confused. Tobi

 September 26, 2012, 13:07 #2 Member   Meindert de Groot Join Date: Jun 2012 Location: Netherlands Posts: 34 Rep Power: 6 Could it be that you are missing the cell volume from the finite volume integration in your Q term? phi = rho would still not solve your problem, because you're still missing [1/s] in that case.

 September 26, 2012, 13:12 #3 Senior Member     Tobias Holzmann Join Date: Oct 2010 Location: Leoben (Austria) Posts: 1,506 Blog Entries: 6 Rep Power: 26 Hi, no its implemented in the flamelet tool from alberto. He added an enthalpy defect like that: Code: div(phi, H) - laplacian(turbulence->mut/sigmat, H) + Qrad where Qrad is calculated with Code: Qrad = 4 * sigma_B * (T_cell^4 - T_env^4) * as Like here: http://www.sandia.gov/TNF/radiation.html Qrad [W/m³] H [J/kg] Well - but you `re right. There is still a s missing :/ I a m confused with taht code.

 September 28, 2012, 05:52 #4 Member   Meindert de Groot Join Date: Jun 2012 Location: Netherlands Posts: 34 Rep Power: 6 Hi Tobi, Have a look at equation 2.29 in the Programmer's Guide.

September 30, 2012, 08:11
#5
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Tobias Holzmann
Join Date: Oct 2010
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Quote:
 Originally Posted by meindert Hi Tobi, Have a look at equation 2.29 in the Programmer's Guide.
Hi,
do you mean the libOpenSmoke Guide or what programmers guide do you mean?

 October 1, 2012, 10:30 #6 Senior Member   Elvis Join Date: Mar 2009 Location: Sindelfingen, Germany Posts: 585 Blog Entries: 5 Rep Power: 15 Hi Tobias, the folks at OpenCFD have discontinued Programmers Guide that is correct but you can still find http://openfoam-extend.git.sourcefor...de.pdf;hb=HEAD

 October 1, 2012, 13:32 #7 Senior Member     Tobias Holzmann Join Date: Oct 2010 Location: Leoben (Austria) Posts: 1,506 Blog Entries: 6 Rep Power: 26 HI, thanks very much. Thats that what I need integration over a volume V - now I know how that works. Thought that the programmers-guide is only the doxygen-code Nice to know. Tobi

 October 3, 2012, 17:24 #8 Member   Meindert de Groot Join Date: Jun 2012 Location: Netherlands Posts: 34 Rep Power: 6 Perhaps it's good to know that you can also find it in your \$WM_PROJECT_DIR/doc/Guides-a4 directory. Tobi likes this.

October 4, 2012, 15:55
#9
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Tobias Holzmann
Join Date: Oct 2010
Location: Leoben (Austria)
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Quote:
 Originally Posted by meindert Perhaps it's good to know that you can also find it in your \$WM_PROJECT_DIR/doc/Guides-a4 directory.

Nice to know.
Working with OF for 3 years now and be in that directory some times but never realized that

stupid!

but thanks!
tobi

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