Some problems with the BVK drag model

Hello, everyone!
I want to solve some multi-phases problems with MFIX-TFM, in which the correction of polydisperse drag models is very important. However, i wonder if the famous BVK (2007) drag model implented in MFIX is wrong or not.

Fistly, the correction function F_cor seems to be wrong in drag_gs.f with the form F_cor = Y_i and DgA = ONE/(Y_i*Y_i) * DgA * F_cor, it seems to be inconsistent with the reference of Beetstra et al. (2007).

Secondly, the stokes drag term F_STOKES seems to be EP_SMx18MugEPg/DPM**2 in the codes. However, according to Azizi et al., (2009), EP_SM should be replaced by (1-EPg), if there are some errors?

Finally, the screenshot of the code in drag_gs.f and the reference of Azizi et al., (2009) are provided in attachments.

Looking for more discusssions!

Kang -

I haven’t had a chance yet to look into this, but I wanted to suggest:

You can modify the code and recompile the mfix solver. It would be interesting to see a comparison of results using the current MFiX code versus a version with your suggested modifications.

– Charles