A self-propelling particle model displaying an asymmetric vortex

Vortex formation in biological grouping is very common in nature. Works have been done formation mechanism, some models could achieve asymmetrical vortex shape. But in most cases the vortex
formed by living organisms is not symmetrical. In the present work, self-driven particle model producing a
symmetric vortex was studied, introducing the factor of individual spatial perceptual anisotropy.The basic
hypothesis is that perception of longitudinal distance is shorter than the true longitudinal distance while lateral
distance is not biased. But this would result in an isotropy of the strength of agentinteractions. Simulations
revealed that when deviation reached a certain level, the population finally resents and maintains an eccentric
vortex state, which coincided with the actual situation better.This would indicate that for a living group to
form an asymmetric rather than asymmetric vortex, spatial perceptual anisotropy may be the major reason
Parameter sensitivity analysis revealed that when group aligning tendency was weak, small distance perception
 deviation had no effect on group behavior; moderate deviation made the group appear as eccentric vortex,
excessive deviation would make the group into a mess. With strong aligning tendency, moderate distance
perception deviation could not change the ending with alignment, but large deviation would make the group
appear as eccentric vortex; excessive deviation resulted in group disorder