Modelling of Pollutants Dispersion from a City Road Tunnel

An outlet portal of a city road tunnel is one of crucial point sources of pollutants to be taken into account when modeling dispersion of pollutants within a city. Namely in case of local scale modeling a correct knowledge of velocity and concentration profiles at the outlet portals may play a non-negligible role. And these profiles are established in a dominant way by the traffic density and speed. In the first part of the paper we are going to present a new Lagrangian - Eulerian approach to moving vehicles througout a traffic tunnel and as a result to give values of flow rate entrained into and out of the tunnel and velocity and concentration profiles at the outlet tunnel portal. In the second part of the paper, dispersion of pollutants from the Plabutsch highway tunnel in Graz (Austria) is predicted for various boundary conditions.