Fig. 4: Order parameters versus obstacle density.
From: Emergence of synchronised rotations in dense active matter with disorder
The figure is drawn for 160 simulations in 60 x 60 boxes with periodic boundary conditions and parameters being the same as in Table 1. The error bars denote the standard error of the averages. a The red dotted line indicates the order parameter of the directional motion. Directional motion seems to be the dominating/only pattern of motion till obstacle density 0.3. In the interval 0.3–0.45, the particles are in a mixed state which we associate with a labyrinth-like pattern. In parallel, the Rotational Ratio (solid green line) shows that till 0.3, there is no rotation, and then in 0.3–0.45, particles start to rotate until nearly all of them are rotating in obstacle densities more than 0.45. The Global Rotation (blue dashed line) increases to approximately 1 at 0.45 obstacle density and then beyond approximately 0.45 decreases. The initial increase shows the emergence of a synchronised rotation state, and the decrease shows the transition from synchronised rotation to the rotation where both directions exist but with synchronisation on a local scale only. b The initial decrease of the average direction shows the loss of directionality in the motion of the particles, while the relatively sudden increase at 0.45 is due to the emergence of synchronised rotation.
