A packed bed of solid particles of density $2000$ kgm$-3$ occupies a depth

of $0\mathrm{.}6$m in a vessel with an internal diameter $0\mathrm{.}1$m$.$ The mass of the

solids in the bed is $5$kg and surface$-$volume diameter is $300\backslash$mu m$.$ Water

$($density $1000$ kgm$-3$ and viscosity $0\mathrm{.}001$ Pa s$)$ flows upwards through

the bed.

a$.$ Calculate the voidage $($fraction of occupied by voids$)$ of the bed

b$.$ Calculated the superficial velocity at which the pressure drop

across the bed is $4130$ Pa