Fig. 2: The effects of gravity on active matter.
From: Active matter in space
On Earth, microscopic active matter is affected by gravity in multiple ways. The most relevant ones include: a Sedimentation and creaming, where the balance between the particle’s and solvent’s densities lead to either an upward or downward motion of the particle in a fluid. Fv and Fg represent the viscous force and gravitational force, respectively. b Convection, where flow patterns at speed u due to density mismatches of various origin transport matter within the sample. The colour scale represents a gradient of density ρ going from low density (ρlow) at the bottom to high density (ρhigh) at the top. c Gravitaxis, where a motile organism or synthetic particle with self-propulsion speed v moves in a direction influenced by gravitational fields.
