Obtaining porous jump coefficients
 

I am a beginner in CFD and I am studying a paper that models a car radiator based on porous medium approach. in order to obtain porous parameters a unit cell of radiator fin should be simulated at different reynolds number to get different pressure drops and inertial and viscous coefficients are calculated. The results according to the papers are shown in the attachments.
delta P = aV+bV^2
I_c=2b/ρl
V_c=a/(lµ)
where l is length of fin (38mm)
ρ is air density
µ air viscosity


my problem is getting the porous jump coefficients (inertial coefficient) shown in the attachments. how is it calculated or obtained? from what i understand face permeability is same as viscous coefficient but what about the inertial coefficient?