Large eddy simulation of the effect of embankment form on highway lateral winds

Intense crosswind conditions significantly affect the safety of vehicular travel on highways. This study investigates the influence of embankment configuration on the crosswind flow characteristics of highways by employing an advanced large eddy simulation (LES) technique based on spatial averaging. The analysis focuses on how embankment height and slope affect the time-averaged velocity field, flow structure, turbulence stress, and statistical properties of pulsating velocities in highway crosswinds. Additionally, the numerical method is validated by integrating LES results with particle image velocimetry (PIV) wind tunnel testing. The results reveal that both embankment height and slope gradient influence the crosswind flow field of roadways. Specifically, the height of the embankment primarily affects the distribution of the time-averaged flow field, while the slope gradient impacts both the time-averaged flow field distribution and the fluctuation characteristics of the flow. The enhancement of these factors significantly increases the flow velocity near the road surface, thereby affecting driving safety. Notably, the slope gradient has a more pronounced effect. Variations in slope gradient lead to variations in the size of the separation bubble above the road surface, as well as changes in Reynolds stress. The slope gradient ratio (l/h) should be maintained at 1.5. The findings of this study are crucial for understanding the mechanisms underlying highway slope instability.