A Numerical Analysis on the Effect of Turbulent Schmidt Number on Numerical Prediction of Pollutant Dispersion within Street Canyons

Abstract

Thispaper presents a numerical analysis on the effect of turbulent Schmidt numberon numerical prediction of pollutant dispersion within street canyons. Fourcases of idealised-2D street canyons were simulated with several modificationsto buildings geometry. The k – ε and RNG k – ε  turbulence closure models havebeen adopted for turbulence modeling and the accuracy of numerical predictionshas been examined by comparing calculated results with the availablewind-tunnel measurements. The simulation results showed that the turbulentSchmidt number is a range of 0.1 to 1.3 that has some effect onthe prediction of pollutant dispersion in the street canyons. For each streetcanyon configuration, an optimum value for turbulent Schmidt number wasdetermined which gives good agreement with the experimental results. In thecase of a flat roof canyon configuration (case-00), appropriate turbulentSchmidt number of 0.6 is estimated using the k – ε model and of 0.5 using the RNG k – ε .