A large scale road pricing system was to be deployed by Kapsch Trafficom. It consists of a gantry structure extending across the highway, fitted with a compartment for the electronic components (see image to the right). Due to safety of operation, the compartment is closed hermetically and can be cooled only via surface convection.

We were comissioned to assess and to optimize the cooling mechanism of the electronic components. A CFD simulation was carried out to estimate the cooling effects due to natural ventilation. The associated equations of buoyancy are inherently unstable and hence difficult to solve. However, using certain stabilization techniques in connection with multi grid algorithms, we were able to obtain efficient and reliable numerical solutions for the problem. They built the basis for an optimized colling channel. In addition to natural cooling, for certain regions across Europe, Peltier elements were necessary.