 No.  Author     Assumptions 
 (1)  Sato and Sekoguchi [37]   0  0   (2)  Pfleger and Becker [38]  0     (3)  Troshko and Hassan [39]  0     (4)  Crowe et al. [14]     PSI cell/ball approximation  (5)  Sommerfeld [40]     Stochastic interparticle collision model  (6) 
Sommerfeld et al. [41]     Langevin equation model 

