Key outcomes

  • GHG emissions minimised
  • Plume dispersion target achieved
  • Regulatorory requirements satisfied

Vehicle emissions form a large source of urban pollution. This results in reduced air quality in large tunnels, which needs to be venitilated. Emissons must be adequately dispersed to ensure safe environmental conditions both in the tunnels and near ventilation points. The geometry in and around tunnels in inevitably complex and needs to be adequately resolved using CFD, to predict the dispersion levels and resulting impacts on air quality and visibility.

tunnel plume South Westerly

Figure 1: CFD simulation of the spread of the plume from tunnel portal emissions.

These images show sample CFD model images from two case studies where Synergetics simulated ventilation systems both inside a tunnel and near the tunnel portals and ventilation stacks using CFD. A series of CFD-based design experiments were conducted to optimise the emission strategy to minimise GHG emissions and achieve acceptable human health and environmental exposures.

CFD simulation of dispersion of truck emissions within a road tunnel.

Figure 2: Simulated exhaust plumes from a truck driving through a tunnel. The ventilation air extraction point is seen in the bottom right.