Pattern Formation in Systems of Active Particles with Chiral Interactions

We analyzed pattern formation in systems of active particles with chiral forces in the context of pedestrian dynamics. To describe the interparticle interactions, we use the standard social force model and supplement it with a new type of force that reflects the chirality. We performed numerical simulations of two pedestrian flows moving in opposite directions in a long corridor. We observed two dynamic phase transitions which occur for varying number density of particles and strength of the chirality force - one from disordered motion to multi-lane motion and another - from the multi-lane to two-lane motion. We develop a qualitative theory which describes the demarcation lines for these phase transitions on the phase diagram chirality-density. The results of our analysis agree fairly well with the simulation data. Our findings may find applications for problems of urban and transportation planning.