A numerical flow model is built based on a commercial package CFX to investigate the interaction effect between the streams in a simplified model of an air-exchange junction, which is usually employed as one of the essential elements to design a cost-effective modern long-road tunnel. The numerical flow model is validated with existing experimental data for the flows in Tee junctions before being employed to study the interaction effects. Results show that the effect is more obvious as the length of the junction is shorter and as the air-exchange rate is higher than 60%.
