external wind

A model tunnel (approximately ten hydraulic diameters) with different designs of the tunnel mouth has been placed in a wind tunnel and has been subjected to the effects of external wind by varying the wind direction at the mouth of the tunnel. In the experimental oriented study pressures have been measured and the airflow has been made visible with smoke and by the sand erosion method (semolina). The relation between the flow ratio and the direction of the wind has been explored.