Steady radial dust outflow
= Steady radial dust outflow
For an axisymmetric steady dust outflow with surface density $\Sigma$ and radial speed $v_r$, number or mass conservation gives $2\pi r\Sigma v_r=\text{constant}$.
= Steady radial dust outflow
For an axisymmetric steady dust outflow with surface density $\Sigma$ and radial speed $v_r$, number or mass conservation gives $2\pi r\Sigma v_r=\text{constant}$.