B. Carissimo, S. Lacour, H. Foudhil,L. Musson-Genon, E. Dupont, M. Milliez, B. Albriet, E. Demael,

L. Laporte,

Tunnel modelling :

the collaboration with the CETU

Atmospheric CFD modelling for environmental applications

at local scale,

History

• CETU: ventilation and environment team

• Technical service of the Equipment Ministry

• Defining state of art, methods for studying tunnels

• Conception of fire protection system

• Environmental studies around tunnels

Collaboration with the CEREA started in 2002

Modelling tools

Polair3D local: • RACM chemistry• Eulerian advection diffusion scheme

Reactive plume/box models• Street model, OSPM …

Mercure_Saturne reactive version

Dispersion around a tunnel portal Vehicle induces flows in a non-ventilated tunnel.

HVG passing produced a high frequency signal on flow velocity

Tunnel also filters vehicle drag effect and produced low frequency variations on the flow velocity

Dispersion around a tunnel portal

Pollutant escape occurs earlier in the street in the case of unsteady flows

Advection effects were found greater than turbulent ones.

Street concentration decrease is lower than 30% in unsteady cases

Lacour and al., UAQ 2003

Dispersion around a tunnel portal Street NO2 concentration increases

From 0% when the primary background pollution is high

Up to 100 % in case of ozone peaks

Ozone availability is a limitation factor for NO conversion near the exit

Dispersion around a tunnel portal Statistical analysis were made for 2 different urban aeras

Reactive models (OPSM1, OSPM2, TNO, Street) were compared

Dilution factors were established for NO2 reactive dispersion around tunnel portal

Guide méthodologique « Etude d’environnement » CETU 2005

Dispersion around a tunnel portal

Dispersion around a tunnel portal Building affects plume geometry in this campaign

The validation of the CEREA model, developed for flat terrain, is not possible with these measurements.

Dispersion around a tunnel portal

NO2 concentration field

wind

Reactive NO2 model was used to study depollution effectiveness of catalytic walls.

A measurement campaign would be carried out by the CETE of Lille around a tunnel portal in Paris and used for validation purposes