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!