Statement of problem Street canyon 2 Mathematical statement of - - PowerPoint PPT Presentation

Statement of problem Street canyon

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Mathematical statement of problem

Governing equations Turbulence models

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• k-ε model of turbulence with Boussinesq closure assumptions (LEVM)
• Non-linear eddy viscosity model (NLEVM)
• Reynolds Stress Model (RSM)

Mathematical statement of problem

Urban vegetation parameterization (Kimura et al., 2003) Governing equation Source/Sink term Momentum equation k- equation ε-equation Reynolds stress transport

η = 1 – fraction of area covered by vegetation – drag coefficient а - LAI

Moving traffic parameterization

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1/c м/c

2D numerical simulation

Model validation Backward facing step (Мосс, 1982)

• experiment
• LEVM
• NLEVM
• RSM

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2D numerical simulation

Model validation Flow past tree (Kimura et al., 2003)

• experiment
• LEVM
• NLEVM
• RSM

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2D numerical simulation

Model validation Computation of pollution concentration in street canyon depending on flow direction (Ketzel , 2000)

• experiment
• calculation

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3D micro-scale model

Inflow boundary conditions

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Numerical simulation of atmosphere dynamics and traffic induced pollution for real area of Tomsk

3D micro-scale model

Velocity field at z = 1,5 m and volume rendering of pollution concentration

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Numerical simulation of atmosphere dynamics and traffic induced pollution for real area of Tomsk

Conclusion

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Unsteady micro-scale model for airflow and pollution transport modeling is developed. Numerical model is based on modern turbulence closure schemes and takes into account urban vegetation and moving transport influence.

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Model evaluation basing on experiments shows that «k- ε» models are enough for urban aerodynamics prediction.

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Numerical prediction of airflow and impurity dispersion for real area of city helps to determine the regions of maximum pollution.

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