Figure 7
Rectification or no rectification as predicted from the computational modeling for different near-wall behaviors and for different funnel geometries.
(A) Green dots indicate rectification and red dots indicate no rectification. The x-axis is the outgoing angle the worms adopt upon leaving the walls. The y-axis is the half-angle between the two arms of the funnel walls as illustrated. Rectification is defined if the average of the density ratio at the steady-state level (after 100 min.) is above 1. (B) Illustration showing the geometrical argument why smaller outgoing angle results in rectification but bigger outgoing angles do not. A worm with small outgoing angles (green and solid line) may encounter multiple barriers without changing its overall direction. A worm with bigger outgoing angles (red and dotted line) may encounter multiple barriers but because of the large outgoing angle, the worm may hit the second barrier in a way that results in “reflected” movement after the second encounter. (C, D) Density ratio of worms in funnels of θ = 30° and funnels of θ = 50° respectively. The ratios are averaged from 4 simulations each having 50 worms. The outgoing angles are color coded as shown in the legend.
