Some Considerations on CFD Modeling of Tunnel Fires

As well known, road or railway tunnels are often proposed for solving traffic problems; however, because of the tunnel geometry and structural characteristics, as well as of the flammability of many transported materials, a tunnel fire is always very dangerous, as shown by many tragic accidents also in recent times. During the fire also the concrete vault may be seriously damaged or even collapse, since the temperatures may be so high to produce dangerous stresses or, sometimes, also explosive “spalling” effects. Nowadays, reliable prediction of the concrete behaviour are possible by means of detailed thermo-structural models, suitably coupled with the thermal field of the fluid inside the tunnel. In this paper some preliminary considerations are presented about this latter aspect of the problem and particularly about the application of a CFD approach for simulating the natural convection fenomena taking place in the proximity of the combustion zone of a tunnel fire.