Vortex inside a street canyon

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kac116
Posts: 11
Joined: Mon Aug 05, 2019 10:22 am

Vortex inside a street canyon

Post by kac116 »

Dear team,
I hope everybody is fine.
I'm modelling a simple street canyon to assess the impact on green infrastructures removing particulate matter.
The area is a simple street canyon with no vegetation. Building height is 10m with a fixed street width of 10m. Grid dimension 180 x 120 x 10 grid, resolution 0.5m x 0.5x x 2m. The core XY domain is 90m x 60m, and 40 nested grids were added to the computational domain. Wind speed at reference height was set to 1 m/s, and the inflow direction was set to 90 degrees. The roughness length is 0.001, and I used simple forcing.
When I analysed the area in Leonardo, I didn't visualise the vortex within the canyon street. Therefore, I got almost the same concentrations on both sides of the street. According to the literature, I should get more significant concentrations at the leeward side, but in this case (and others I simulated) I have the same concentrations on both sides of the canyon street. Could you give advice to solve this situation? As I said before, I modelled different scenarios, and I got the same results.

Thank you and stay safe!

Tim
Posts: 1723
Joined: Mon May 15, 2017 3:46 pm

Re: Vortex inside a street canyon

Post by Tim »

Hi,

Could you attach some screenshots here, where wind vectors are enabled?
I cannot imagine how the street canyon is orientated from the description right now.

Best regards,
Tim

kac116
Posts: 11
Joined: Mon Aug 05, 2019 10:22 am

Re: Vortex inside a street canyon

Post by kac116 »

Thank you for your reply. Yes, of course. I attached the screenshot of the area with vectors.
Thanks
Attachments
Area.png

Tim
Posts: 1723
Joined: Mon May 15, 2017 3:46 pm

Re: Vortex inside a street canyon

Post by Tim »

Hi,

I think the wind speed is very low and additionally the wind is blocked by the building, even further decreasing the wind speeds within the canyon. The pollution is thus not distributed and highest concentrations are found directly above the source of emission.

Best regards,
Tim

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