Implementation Actions

B5. Modelling of CFD code -reactive chemical- NOx deposition rate in urban scenarios for the decontaminant effect of photocatalytic materials in urban scenarios

This action is being carried out by the Atmospheric Pollution and Ecotoxity Modelling Unit of the Environment Department of CIEMAT.

A Computational Fluid Dynamics (CFD) model is used to simulate the dispersion of reactive atmospheric pollutants and the nitrogen oxide (NO) deposition effect on a photocatalytic surface in urban settings. Action B5 focuses on modelling the dispersion of NO and NO2 in determined conditions, registered in the experimental campaigns carried out in Action B4. Action B5 has been divided into three phases:

  • Phase I: Modelling the NO deposition effect due to the photocatalytic material applied to the road surface on Paseo de la Chopera (Alcobendas). This phase is developed. The results obtained allow us to conclude that:
    • There is hardly any difference between NO and NO2 concentrations in both chemical implemented mechanisms (photo-stationary NOx-O3 and another more complex NOx-Ox-VOC), under the specific studied conditions.
    • The results of the simulation fit the experimental data quite well.
    • The amount of NO deposit - considering both chemical mechanisms - gives differences in concentration, at 1 m height at the points of measurement, less than 1 ppb during all the analyzed time.
  • Phase II and III: Modelling the NO deposition effect due to the photocatalytic material applied to the pavement (phase II) and façade.

Phase I figures

Figure 1. Geometry of the computational domain of the area in Alcobendas and zoom in Paseo de la Chopera where the experimental field investigation is carried out (Action B4). The region in red represents the location of the emissions and the yellow region is the area of the photocatalytic material. Figure 2. Concentration of NO and NO2 in average ppb during the whole hour from 12.00UTC to 13.00 UTC at the measurement points. Figure 3. Concentration of NO and NO2 in ppb at 13.00 UTC at a 1m height in the study region Figure 4. Differences in NO concentration with and without photocatalytic asphalt(difNOphot = NOnoPhot - NOwithFot) at 13.00 UTC. Figure 5. Vertical profiles of NO concentration differences with and without photocatalytic asphalt (difNOphot = NOnoPhot - NOwithFot) in points 1-4 of the measurement at 13.00 UTC