Modeling and simulation of crowd dynamics in low-speed water flow environment

In urban waterlogging scenario, the complexity of crowd evacuation escalates exponentially due to the interference of water flow. Beyond physical obstacles, the hydrodynamic environment exerts profound psychological impacts on evacuees, often triggering abnormal behaviors such as panic and irrational herding. In this paper, an extended social force model is proposed to simulate crowd evacuation in low-speed water flow environments. Treating the water flow as a uniform flow, the model integrates multi-faceted factors, including pedestrian panic level, herd mentality, and the force exerted by the flowing water. The effects of the magnitude and direction of the water flow and individual mass on pedestrian movement stability and evacuation efficiency are explored. Macro self-organization phenomena, such as following and layering, are observed and the corresponding dynamic mechanism is analyzed. Results show that evacuation efficiency depends on water depth and the magnitude and direction of the water flow. Notably, pedestrian movement stability exhibits a positive correlation with individual mass, indicating that heavier individuals maintain better balance in water currents. These findings not only enrich the theoretical framework of hydrodynamic evacuation modeling but also provide practical guidelines for optimizing evacuation strategies in flood-prone urban areas, thereby enhancing the effectiveness of disaster prevention and mitigation efforts.