A packed bed of solids of density $2000$ kg$/$m$3$ occupies a depth of $0\mathrm{.}6$m in a cylindrical vessel of inside diameter $0\mathrm{.}1$m$.$ The mass of solids in the bed is $5$ kg and the surface$/$volume mean diameter of the particles is $300\backslash$mu m $($Water density $1000$ kg$/$m$3$ and viscosity $0\mathrm{.}001$ Pas $)$ flows upwards through the bed.$$a$.$ What is the voidage of the packed bed$$b$.$ Use a force balance over the bed to determine the bed pressure drop when fluidized. $$c$.$ Hence, assuming laminar flow and that the voidage at incipient fluidization is the same as the packed bed voidage, determine the minimum fluidization velocity. $-$ Verify the assumption of laminar flow.$$