Preprints
https://doi.org/10.5194/gmd-2020-432
https://doi.org/10.5194/gmd-2020-432

Submitted as: model description paper 26 Mar 2021

Submitted as: model description paper | 26 Mar 2021

Review status: this preprint is currently under review for the journal GMD.

urbanChemFoam 1.0: Large-Eddy Simulation of Non-Stationary Chemical Transport of Traffic Emissions in an Idealized Street Canyon

Edward C. Chan and Timothy M. Butler Edward C. Chan and Timothy M. Butler
  • Institute for Advanced Sustainability Studies (IASS), Potsdam, Germany

Abstract. This paper describes a large-eddy simulation based chemical transport model, developed under the OpenFOAM framework, implemented to simulate dispersion and chemical transformation of nitrogen oxides from traffic sources in an idealized street canyon. The dynamics of the model, in terms of mean velocity and turbulent fluctuation, are evaluated using available stationary measurements. A transient model run using a photostationary reaction mechanism for nitrogen oxides and ozone subsequently follows, where non-stationary conditions for meteorology, background concentrations, and traffic emissions are applied over a 24-hour period, using regional model data and measurements obtained for the City of Berlin in July, 2014. Diurnal variations of pollutant concentrations indicate dependence on emission levels, background concentrations, and solar state. Comparison of vertical and horizontal profiles with corresponding stationary model runs at select times show that, while there are only slight differences in velocity magnitude, visible changes in primary and secondary flow structures can be observed. In addition, temporal variations in diurnal profile and cumulative species concentration result in significant deviations in computed pollutant concentrations between transient and stationary model runs.

Edward C. Chan and Timothy M. Butler

Status: open (until 21 May 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CEC1: 'Comment on gmd-2020-432', Juan Antonio Añel, 20 Apr 2021 reply
    • AC1: 'Reply on CEC1', Edward C. Chan, 21 Apr 2021 reply
      • AC2: 'Reply on AC1', Edward C. Chan, 22 Apr 2021 reply
  • RC1: 'Comment on gmd-2020-432', Anonymous Referee #1, 22 Apr 2021 reply

Edward C. Chan and Timothy M. Butler

Edward C. Chan and Timothy M. Butler

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Short summary
A large-eddy simulation based chemical transport model is implemented for an idealized street canyon. The dynamics of the model are evaluated using stationary measurements. A transient model run is also conducted over a 24-hour period, where variations of pollutant concentrations indicate dependence on emissions, background concentrations, and solar state. Comparison stationary model runs show changes in flow structures concentrations.