ii$)$ Suppose we know the cut diameter $D_{\text{c}\text{u}\text{t}}=3\mathrm{.}8m$ for a particular cyclone, what is its collection efficiency for a particle of $4\mathrm{.}5m$ diameter?

$=\frac{N{V}_c{}_{\text{p}\text{a}\text{r}\text{t}}{D}^2}{9W}$

Here, $N=$ the number of rotation, $V_c$ is gas rotation velocity, ${}_{\text{p}\text{a}\text{r}\text{t}}$ is the density of particle, $D$ is the particle diameter, $W=$ cyclone inlet width, and $=$ viscosity of the fluid.

$(5$ marks$)$