Abstract: A numerical simulation is conducted on the external flow field characteristics of windshield in this paper for revealing their effects on rain droplet movement. Firstly standard k-ε turbulence model is used to set up the calculation region of windshield model and generate its mesh control region. The airflow model of external flow field of windshield is established with boundary conditions set and hybrid mesh used for key regions. Then CFD software COMSOL Multiphysics is adopted to perform numerical simulation on air flow model for analyzing the characteristics of pressure distribution and attached airflow velocity on the external surface of windshield. . The results of experiment show that the simulated characteristics of attached airflow on windshield surface are basically in accordance with experiment results, verifying the effectiveness of the model built. Next, control variable scheme is utilized to simulate the effects of the airflow velocity on and the inclined angle of windshield on its flow field characteristics. The results indicate that the change of airflow velocity affects only the values of surface pressure and attached airflow velocity, but not the patterns of pressure distribution and attached airflow direction on windshield surface, while the inclined angle of windshield has larger effects on external flow field. With the reduction of windshield inclined angle, the velocities of attached airflow tends to be more uniform. Finally, the effects of different airflow velocities on the movement of rain droplets are studied with a result providing an important reference value and guiding significance for the control of rain droplet motion.

Key words: windshield, external flow field, turbulence model, flow field characteristics, rain droplet motion