Axial repulsion of pusher stresslets
= Axial repulsion of pusher stresslets
{title2=$\ell^3=\ell_0^3+3St/(2\pi\mu)$}
Two equal parallel axial point <stresslets> with positive strength $S$ and separation $\ell$ have relative <velocity> $S/(2\pi\mu\ell^2)$. Identical self-propulsion cancels in their relative motion. The solution is the displayed cubic separation law while the far-field approximation is valid.