A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Quantifying inflow uncertainties in RANS simulations of urban pollutant dispersion
AbstractNumerical simulations of flow and pollutant dispersion in urban environments have the potential to support design and policy decisions that could reduce the population's exposure to air pollution. Reynolds-averaged Navier-Stokes simulations are a common modeling technique for urban flow and dispersion, but several sources of uncertainty in the simulations can affect the accuracy of the results. The present study proposes a method to quantify the uncertainty related to variability in the inflow boundary conditions. The method is applied to predict flow and pollutant dispersion in downtown Oklahoma City and the results are compared to field measurements available from the Joint Urban 2003 measurement campaign. Three uncertain parameters that define the inflow profiles for velocity, turbulence kinetic energy and turbulence dissipation are defined: the velocity magnitude and direction, and the terrain roughness length. The uncertain parameter space is defined based on the available measurement data, and a non-intrusive propagation approach that employs 729 simulations is used to quantify the uncertainty in the simulation output. A variance based sensitivity analysis is performed to identify the most influential uncertain parameters, and it is shown that the predicted tracer concentrations are influenced by all three uncertain variables. Subsequently, we specify different probability distributions for the uncertain inflow variables based on the available measurement data and calculate the corresponding means and 95% confidence intervals for comparison with the field measurements at 35 locations in downtown Oklahoma City.
HighlightsThe effect of inflow uncertainties in simulations of urban dispersion is quantified.The results are compared to the JU2003 experiments.Variance-based analysis shows wind direction is the dominant uncertain parameter.All uncertain parameters exhibit a non-negligible effect on urban dispersion.The results identify areas in the urban canopy more sensitive to inflow uncertainty.
Quantifying inflow uncertainties in RANS simulations of urban pollutant dispersion
AbstractNumerical simulations of flow and pollutant dispersion in urban environments have the potential to support design and policy decisions that could reduce the population's exposure to air pollution. Reynolds-averaged Navier-Stokes simulations are a common modeling technique for urban flow and dispersion, but several sources of uncertainty in the simulations can affect the accuracy of the results. The present study proposes a method to quantify the uncertainty related to variability in the inflow boundary conditions. The method is applied to predict flow and pollutant dispersion in downtown Oklahoma City and the results are compared to field measurements available from the Joint Urban 2003 measurement campaign. Three uncertain parameters that define the inflow profiles for velocity, turbulence kinetic energy and turbulence dissipation are defined: the velocity magnitude and direction, and the terrain roughness length. The uncertain parameter space is defined based on the available measurement data, and a non-intrusive propagation approach that employs 729 simulations is used to quantify the uncertainty in the simulation output. A variance based sensitivity analysis is performed to identify the most influential uncertain parameters, and it is shown that the predicted tracer concentrations are influenced by all three uncertain variables. Subsequently, we specify different probability distributions for the uncertain inflow variables based on the available measurement data and calculate the corresponding means and 95% confidence intervals for comparison with the field measurements at 35 locations in downtown Oklahoma City.
HighlightsThe effect of inflow uncertainties in simulations of urban dispersion is quantified.The results are compared to the JU2003 experiments.Variance-based analysis shows wind direction is the dominant uncertain parameter.All uncertain parameters exhibit a non-negligible effect on urban dispersion.The results identify areas in the urban canopy more sensitive to inflow uncertainty.
Quantifying inflow uncertainties in RANS simulations of urban pollutant dispersion
García-Sánchez, C. (author) / Van Tendeloo, G. (author) / Gorlé, C. (author)
Atmospheric Environment ; 161 ; 263-273
2017-04-10
11 pages
Article (Journal)
Electronic Resource
English
Quantifying inflow uncertainties for CFD simulations of the flow in downtown Oklahoma City
| British Library Online Contents | 2014
Quantifying inflow uncertainties for CFD simulations of the flow in downtown Oklahoma City
| Online Contents | 2014