Drag models units

hunger's picture
Submitted by hunger on Thu, 02/18/2016 - 11:27

Hi all!

I was digging into the source code of the drag models (especially into Gidaspow).

I found a comment that says that Ksl should have [N/m3 / m/s], which I would agree if I analyse the momentum equation e.g. in cfdemSolverPisoScalar.
Then I tried to track the calculation of Ksl down to the code of the drag model and I found the following line for implicit momentum coupling:

dragcoefficient --> cd --> cds --> Ksl

What I didn't understand anymore was the calculation of 'dragcoefficient'. If I didn't miss something while tracking things down in the source code, 'dragcoefficient' should also have [N/m3 / m/s]. But it is calculated:

dragcoefficient = Vs * betaP

and 'betaP' has the units [N/m3 / m/s], which means 'dragcoefficient' would have [N/m3 / m/s * m3].

I think I missed something ... any suggestions?

Best regards
Harald

Sarah Gildein | Wed, 07/11/2018 - 08:37

I am not aware about this, but I want know more about your topic. I am a newbie here, I read some unique posts from here. ! I think this is connecting with and enlightening material. Much thanks to you such a great amount for thinking about your substance. Dissertation writing service

gelinhan | Thu, 07/12/2018 - 08:09

Hi Harald,

The unit of dragcoefficient is right. Please refer to the member function impMomSource of implicitCouple.C where the Ksl is divided by the mesh volume. Hope this helps.

Regards,
Linhan