Sedimentation length
= Sedimentation length
{title2=$\ell_g=k_BT/(m_bg)$}
For noninteracting particles with positive buoyant mass $m_b$ in a gravitational field, a dilute <thermodynamic equilibrium> profile is proportional to $e^{-z/\ell_g}$ with $\ell_g=k_BT/(m_bg)$. Uniformity over a vessel height $H$ requires $H\ll\ell_g$. Requiring only $\ell_g$ to exceed a particle radius is a weaker microscopic gravity-versus-diffusion condition.