Latin symbols C Fluctuating component of solids instantaneous velocity (m/s) c Instantaneous solids velocity (m/s) C d Drag coefficient (-) D Bed diameter (m) d p Particle diameter (m) D s Solid rate-of-shear tensor (1/s) e Particle-particle restitution coefficient (-) e w Particle-wall restitution coefficient (-) g Gravity vector (m/s 2) g Gravity vector magnitude (m/s 2) g 0 Radial distribution function (-) G s Solids mass flux [kg/(m 2 s)] I Vector of interaction forces between gas and solid phases (N/m 3) k Θ Granular energy diffusion coefficient (Pa s) L Bed height (m) nsd Number of spatial dimensions (-) p Apparent order of GCI method (-) P Gas pressure (Pa) P s Solids pressure (Pa)