Spatiotemporal flow force model of source/sink human mobilities within city

Human mobility is of importance in supporting smart cities, urban planning and constructions of resilient environments. Previous studies on dominant mobility models (i.e., gravity and radiation models) rarely describe the refined spatiotemporal process of human mobility flow forces especially within city. To address this gap, this paper proposes a spatiotemporal flow force model (FFM) of sink/source human mobilities within city, which is derived from Navier-Stokes equation in the field of fluid mechanics. The FFM model outperforms the gravity and radiation models in modeling the refined spatiotemporal flow force process of source/sink human mobilities, in the aspect of intensity and direction of mobility flow force. Comparison results show that the gravity and radiation models in the source mobility scenario can give a rough force estimation about the total outflow from source mobility areas while without the capability of explaining the specific directions of mobility flow from source mobility areas. Pearson correlation coefficient between the intensity results of the two models and those of FFM range from 0.65 to 0.90 and direction differences between the results of the two models and FFM respectively show no clear regularity. In the sink mobility scenario, the direction of mobility flows can be estimated well by the gravity and radiation models while the intensity of mobility flow between small-scale areas within cities is susceptible to inaccuracies. Pearson correlation coefficient ranges from 0.13 to 0.59 and direction differences follow a stepped distribution from high to low within the range of 0 degrees to 180 degrees. In addition, the potential field of human mobility flow force provides a powerful tool for visually analyzing mobility flows within cities. This proposed model enriches human mobility models and is generalizable in supporting smart cities, urban planning, and constructions of resilient environments in terms of the refined spatiotemporal process of mobility flow force.