= Burst transport under inverse-size radial drag
{title2=$r^2(D,t)=r_0^2-2\gamma t/D$}
For grains of fixed diameter $D$ released instantaneously at $r_0$, the drift law $\dot r=-\gamma/(rD)$ integrates to the displayed size-radius map. The time to radius $r<r_0$ is $t_r(D)=D(r_0^2-r^2)/(2\gamma)$. Grains therefore arrive in increasing diameter order. This model of <Poynting–Robertson drag> assumes nearly circular <Kepler orbits>, fixed positive $\gamma$, and no grain loss or diameter changes before arrival. At a positive time, the map is monotone in $D$ and allows the initial <power-law size distribution> to be transformed into a spatial distribution or an arrival-time distribution.
Back to article page
