Q$40.$ Fluidisation

Air of a density of $0\mathrm{.}716\frac{kg}{m^3}$ and viscosity of $2\mathrm{.}66*{10}^{-5}Pa*s$ is passing through spherical sand

particle bed of a density of $2290\frac{kg}{m^3}$ and an average $x_{sv}$ of $0\mathrm{.}43mm.$ At incipient fluidization, the

bed height is $0\mathrm{.}25m$ and the apparent bed density is $820\frac{kg}{m^3}.$ Determine the $U_{mf}$ and pressure drop.

Validate your calculation.