CFD Model, help

grasshopper butterfly
1

Hi, more than a question, a help on “how to do for” …
I would like to understand better if between a glazing facade and a metallic shading (more or less perforated) there is a re-irradiation due to overheating of the shading.
I have already done calculations with EnergyPlus (simplified model), but I would like to do it with a CFD analysis. How can I approach it? So far I have used 2 butterfly only for internal mechanical ventilation … thanks a lot to those who give me a hand (or an example file to share all)!
Massimiliano

1 Like
2

@OlivierDambron should be able to help in this case. Butterfly is missing a number of features necessary for modeling heat transfer accurately but you can get around that by editing the file and using OpenFOAM directly once the model is created.

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Thank you very much @mostapha! I hope I can understand something more, it’s an interesting topic …

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hi Massimiliano,

first things first,

are you trying to understand the glazing’s temperature when affected by irradiation from the hot metallic shading?

or do you have all the constant surface temperatures and you are just trying to see how this whole system affects the air temperature/ behavior around it?

Best,
Olivier

5

Thanks @OlivierDambron,
the main objective is to understand the temperature of the glass (or the amount of the irradiation) when heating expanded metal.
It would also be interesting to understand what happens in that area as the distance between glass and shading varies …
Can you help me?
Best
Massimiliano

6

@MassimilianoBusnelli

What you are referring to is a multiregion type of simulation where both solid and fluid are being calculated.Typical solver from openfoam is ChtMultiRegionFoam. I suggest to check the tutorials of openfoam directly to see if any of those could match your case (let me know if you need some indications on how to find them) and have a look online. https://openfoamwiki.net/index.php/ChtMultiRegionFoam
It’s also a topic that I’m interested to explore with openfoam, but the list is just growing, let’s stay in touch.

As far as I’ve tested openfoam, I’ve been focusing on indoor air behavior with radiation activated but with constant surface temperature and emissivity.

You can also consider using THERM in this case for a fair 2D simplification. https://windows.lbl.gov/software/therm

best,
OIivier

1 Like
7

Thank you very much @OlivierDambron, I study the solver that you told me. If you give me an indication on where to find tutorials, better. Thanks. Yes, you’re right, the list of interesting things to understand is really long! While for therm (which I use well for thermal bridges and surface temperatures) I did not understand how it can help me … What should I set for solar radiation? Thank you again. Massimiliano

8

Hi @MassimilianoBusnelli

Not too sure about Therm, sorry.

For surface temperatures with solar radiation, I would calculate them through energyplus and set them as constant in the cfd simulation to capture a point-in-time.

It’s convenient to write cases using Butterfly and execute them through openfoam7 on ubuntu running on the Window-Subsystem for Linux (sounds cumbersome but it’s a piece of cake)
How to Install WSL on Windows 10. Follow the instructions here to install openfoam on Ubuntu Download v7 | Ubuntu | OpenFOAM

Once you launch the ubuntu window command line you can navigate in and out of folders in your computer and access the butterfly case folder where to run commands. Type in :

  • “cd /folder” to navigate into folders
  • “cd …” to navigate backwards
  • “ls” to list items in folder
  • “cd /mnt/c/Users/Massimiliano/butterfly/case1” to access your case

Anyway you can access the list of official openfoam Tutorials by typing
“cd $FOAM_TUTORIALS”
or in your case
“cd $FOAM_TUTORIALS/heatTransfer/chtMultiRegionFoam”

Copy a relevant case onto your butterfly folder so that you can read and modify its files on windows using notepad++ to avoid the cryptic ubuntu command line:
“cd $FOAM_TUTORIALS/heatTransfer/”
" cp - r chtMultiRegionFoam /mnt/c/Users/Massimiliano/butterfly"

Once you’ve tweaked and adapted your tutorial to your specific case then you access it through Ubuntu again and run commands:
“cd /mnt/c/Users/Massimiliano/butterfly/case1”
“blockMesh”
“surfaceFeaturextract”
“snappyHexMesh”
…

let us know where you get,
Best,
Olivier

1 Like
9

Really thank you very much @OlivierDambron.
In the week I try. I have already installed bluecore cfd, but I follow your path …
thank you again,
massimiliano