I was wondering if there is a way to combine the effect of an exterior CFD with a series of obstructions in an urban context and an interior CFD influenced by the exterior CFD wind pressure coefficients in the building facades.
Have you done this before? how did you address it? is it required to interpret and modify by hand the discharge coefficient for every window? or the wind factor per facade?
Thanks and sorry for my ignorance in this topic
Did somebody face this before? How did you address it?
Hi @julioamodia89 I have done this before using SimScale. Honestly, it’s one of the coolest things I have done. My workflow was something like this:
- Upload a microclimate like geometry, site, contextual buildings and topology if necessary.
- Run an external simulation in the multi-directional PWC analysis. I assume the pressure at each opening to be uniform, so I read the pressure at the centre of each opening.
- Convert all the pressures from all openings tp pressure coefficients. Usually, I have a row for each opening and a column for each direction, as a table.
- Import a geometry representing an inside space (room, floor etc), with clear surfaces for openings. These will be used as the boundary conditions. If you want to include openings and resistances from the window geometry, I include a volume to apply what we call a porous media. You can define it indirectly using the estimated discharge coefficient.
- For each scenario you wish to simulate, create a new simulation (CHTv2), defining the correct pressure values at the opening boundaries, I.e. you want to simulate an indoor space under natural ventilation with 15 degrees ambient temperature and wind at 5m/s from the southwesterly wind direction? Use the pressure values back-calculated from the pressure coefficient in your table to define it.
- Observe the flow fields inside the building from the results.
This does assume a few things. For example, the openings are small, and flow through the building is not that high due to internal resistances. If this was an ample open space, for example, a rooftop garden with a cover, then a different approach should be taken.
Also, if you wanted to be fancy, you could use the API to automate a lot of this or even write something natively as grasshopper components.
If you want to see our example on this its here for the indoor study or here for the external study (Login required, you should be able to sign up to a non-commercial account and get access).
I hope this helps! I would also be interested to know your solution if you already managed it.
Both your links require a login.
Ah true, you can sign up for a community account, or alternatively, let me know what you would like to see and I can screenshot it for you?
I edited my original post to caution signup is required.
That is a good question/statement. Let me see what is the most relevant and post that. Bare with.
Here is a blog post on the same project. I think it’s a good overview, but if you need details, the project links are still relevant above. Have a good day!
Thanks for the update on the link. I actually gave up on trying any sort of CFD myself and I’m happy to have this done by a specialist who’s capable of judging the results.
Anyway, I’m looking at many different topics on this forum and recently there’s been quite some spam with funny links. So that’s the main reason I posted here…
That is unfortunate about your experiences with CFD, but great you found a solution/person. We are aiming to put this in the hands of the less experienced, so if you ever fancy trying it yourself, you would be welcome! Likewise, it is a shame you are getting lots of spam here, the links are genuine and do lead to real projects, but I understand your concern, we have a SimScale forum also, and on occasion, similar issues.