CFD SIMULATION OF A COUGHING DROPLET DIFFUSION IN THE ACCELERATING-MOTION METRO CABIN
Keywords: the modified RANS k - ε turbulence model, inertial effects on background flow, droplet diffusion, subway cabin, with varying acceleration motion state, CFD simulation
Abstract. The metro cabin provides an effective way for the spread of the pneumonia virus when provides convenience to human beings. The cabin undergoes a series of motions of acceleration speed, uniform speed, and deceleration speed during the one-station travelling process. The induced flow of the accelerated moving cabin is the determinant of the air drag force on the cough droplets, and effect on the time-frequency characteristics and motion trajectories of droplets of different sizes. In this study, we established a momentum equation on droplets, affected by the inertial force correction term in the non-inertial frame. Then added the drag force from the velocity difference between the cough droplets and the background airflow, and simulated configurations as: 1) droplet spreading aerodynamic process from different face orientations of infected dummy, 2) six groups of size particles, and 3) variable speed motion phases. The numerical simulation provides a physical analysis idea for studying the relationship between the two-phase flow under the action of inertial force. This design of a ventilation environment in public transportation helps to reach a more profound understanding of the inertial precipitation mechanism of droplet jets.