NUMERICAL SIMULATION OF FLOW FIELD AND POLLUTANT DISPERSION IN A LONG HIGHWAY TUNNEL

摘要

This paper presents CFD analysis of flow field and pollutant dispersion in a naturally ventilated long highway tunnel in the middle Himalayas. A commercial CFD code (CFX) has been used for numerical simulation of the turbulent flow and scalar transport of carbon monoxide (CO) and nitrogen oxides (NOx). Vehicular emissions have been modelled as point sources. Standard k-e turbulence model has been used in steady state flow analysis. Presence of fine sand in the air has been accounted for by assuming the working fluid to be a homogeneous mixture of sand and air. Simulation results provide an estimate of variation of the pollutant concentrations in different parts of the tunnel and clearly show the effect of variable percentage of fine dust/sand on ventilation in the tunnel.