Fig. 2
From: Oscillatory surface rheotaxis of swimming E. coli bacteria
Summary of reorientation mechanisms included in the model. Wall effects: a Steric and hydrodynamic interactions align swimmers with surfaces. b Clock-wise torque from the counter-rotation of the cell body and flagella. Flow effects: c Left-handed helical flagellar bundle in shear reorients swimmers to the right. d Jeffery orbits of elongated bacteria. Flow-wall coupling: e Weathervane effect reorients swimmers to the upstream direction. For all these individual contributions (a–e), the corresponding orientation dynamics in ψ–θ phase space are shown in Supplementary Fig. 1. Combinations of the different effects give f swimming in the upstream direction (a, b, e), g bulk reorientation, biased to the right due to flagellar chirality (c, d), and h oscillatory swimming, oriented slightly upstream due to the weathervane effect (d, e). Green (red) stars are stable (unstable) orientation fixed points, and the blue diamond is a saddle point. The parameters used are given in the caption of Fig. 1, with shear rate \(\dot \gamma = 5\,{\mathrm{s}}^{ - 1}\)
