Presentation on theme: "ANALYSIS OF NUMERICALLY MODELLED LOCAL CONCENTRATION GRADIENTS IN STREET CANYONS: IMPLICATIONS FOR AIR QUALITY MONITORING J.M. Crowther 1, D. Mumovic 2,"— Presentation transcript:
ANALYSIS OF NUMERICALLY MODELLED LOCAL CONCENTRATION GRADIENTS IN STREET CANYONS: IMPLICATIONS FOR AIR QUALITY MONITORING J.M. Crowther 1, D. Mumovic 2, Z. Stevanovic 3 1 School of the Built and Natural Environment, Glasgow Caledonian University 2 The Bartlett, Faculty of the Built Environment, University College, London 3 Institute of Nuclear Sciences, University of Belgrade
Objectives of this study To analyse numerically modelled, local concentration gradients in street canyons To make recommendations for the positioning of air quality monitoring stations
Cases Studied 1.A single street canyon 2.A staggered cross-road 3.An idealised complex configuration of several street canyons
Methodology PHOENICS with different turbulence models: –Standard k-epsilon –Renormalisation group k- model –Chen-Kim modification of k- model –Two-scale k-
Validation Comparison with air quality data collected for Glasgow city Council, Scotland Wind tunnel data from the University of Hamburg, Germany
Incompressible, Steady-state Navier Stokes equations k = turbulence kinetic energy per unit mass U i = mean velocity, u i = turbulence velocity P = pressure, = density, μ = dynamic viscosity t = turbulent viscosity
Pollutant Transport Equations Turbulence Contribution to the Pollutant Flux Conservation of Pollutants D = Laminar Diffusivity, C = Turbulent Schmidt No.
General Transport Equation Property with source S and diffusivity
Standard k- Turbulence Model k =1.0, =1.314, C 1 =1.44, C 2 =1.92, C = 0.09
RNG k- Turbulence Model k =0.7914, =0.7914, C 1 =1.42, C 2 =1.68, C = 0.0845 o = 4.38, = 0.012
Chen-Kim k- Turbulence Model k = 0.75, =1.15, C 1 =1.15, C 2 =1.9, C 3 = 0.25, C = 0.09
Factors for Location of Monitoring Equipment Practicality of Location Practicality of Location Level of Turbulence Level of Turbulence Local Concentration Gradients Local Concentration Gradients Suitable Location Suitable Location
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