Full scale CFD modeling of the Mont Blanc tunnel ventilation system

A exible and versatile full-scale CFD modeling strategy of the air ow in a road tunnel is described. As applied to the case of the Mont-Blanc tunnel, the model includes the entire tunnel length and main characteristic elements of its hybrid ventilation system, including lateral air intake, longitudinal jet fans and air extraction vents. Each of these elements has been modeled, tested and calibrated independently with the help of experimental data collected on-site. In order to simplify the generation of the computational model, seven elementary modules (each 50 m long) have been singled out and meshed independently; such modules, if properly combined, can represent the whole tunnel or just one of its segments. Automatic mesh manipulation scripts were implemented to combine and merge such modules and generate the whole model, which consist of more than two hundred million cells. The validity of the modeling strategy, when appropriate, is veried by means of steady state simulations performed using data from previous in vivo experimental campaigns. Results demonstrate that the deviation between numerical and experimental data is, in most cases, lower than the measurement error of the experimental procedure.