Initially, the gas velocity was set at zero throughout the entire bed. A uniform velocity profile for the gas phase was applied as an inlet condition. A value for the pressure was specified at the outlet of the fluidized bed. For the gas phase, no-slip and non-penetrating wall conditions were considered. For the solid phase, the slip (Johnson and Jackson 1987) according to Table 2.2,
where vs,para is the particle slip velocity parallel to the wall and в is the granular temperature. в is the specularity coefficient between the particle and the wall, which is defined as the average fraction of relative tangential momentum transferred between the particle and the wall collision. A value for a specularity coefficient of 0.2 was assumed. The Johnson and Jackson (1987) wall boundary condition for granular temperature was also considered:
A value of restitution coefficient esw of 0.2 between the particle and the wall and a value of restitution coefficient ess of 0.9 between particles were assumed (see Jang and Arastoopour 2014 for a more detailed explanation).