Computational study of effects of traffic force on the ventilation in highway curved tunnels

A computational study using dynamic mesh method was carried out to investigate the effects of traffic force caused by a moving vehicle on ventilation in a straight road tunnel and several curved road tunnels with various radii. It has been found that the effect of the radius of the curved tunnel on the traffic force is significant, especially in a curved tunnel with a smaller radius. The traffic force induced by a moving vehicle and the effective drag coefficient increase with the decrease of the radius of the tunnel. The difference between the traffic force in curved tunnels and that in a straight tunnel is negligible when the radius is greater than 2000 m. The static pressure around the vehicle is significantly lower than it is away from vehicle due to the combination of the boundary layer separation and the airflow retardation. And the lowest value occurs at the front of the vehicle. With the decrease of the radius of curved tunnels, the suction around and behind the vehicle is obviously subjected to the limited space due to a bigger vortex approximately approaching the right concave wall and this consequently causes a lower static pressure and a lower dynamic pressure.

Research highlights
► We model five curved tunnels and a straight tunnel to simulate the traffic force caused by a moving vehicle.
► The traffic force increases with the decrease of radius of the tunnel.
► The difference in the effective drag coefficient between curved tunnels and a straight tunnel can be ignored as the radius is bigger than 2000 m.