Hi, I am doing experiment in a laboratory scale fluidized bed. Here is my concern, in literature it says that minimum fluidization velocity increases with decrease in bed diameter and vise-versa. but in my experiment i got the reverse. minimum fluidization velocity decreases with decrease of bed diameter for same bed height. (Bed Dia=3.5 cm and 12.3 cm, bed height= 5 cm, particles=: glass beads 1mm spherical).

can any one tell me, why this is happening? is there any explanation for this?

Thanks.