$30.$ Given a pipe flow with internal diameter $75$ mm$,$ carrying a gas$-$liquid mixture at superficial velocities of $2$ m$/$s for gas and $0\mathrm{.}2$ m$/$s for liquid, identify the flow regime using a generic flow regime map. Then, calculate the expected pressure drop per meter.

$31.$ Calculate the volume fractions of gas, solid, and liquid phases in a three$-$phase flow with volumetric flow rates of $0\mathrm{.}03$ m$/$s for gas, $0\mathrm{.}006$ m$/$s for solid, and $0\mathrm{.}02$ m$/$s for liquid in a $100$ mm diameter pipe. Subsequently, determine the mixture density.