Butterfly Outdoor air flow Results = 0

ladybug

#1

Hi all,
I’m testing butterfly with a provided example 01_0_outdoor_airflow.
After installing (through hundreds of attempts, I hope I’ve eventually done it right) OpenFoam and everything run successfully (see pic.1 and 2).


Opening the file, I used update Ladybug component and have no errors. Thanks, @mostapha for the comment earlier -

Just noticed a slight difference in some components, such as Creat Case From Tunnel. There’s no more input for meshParams (pic 3), but I guess it’s not critical as it can be set in the snappyHex mesh component.

Also, two other items now have a write category, which I populated with boolean (pic 4).

At the end all values = 0 (pic 5) and no pressure is creaed in the model (pic 6)


Any advice on how to fix the issue?
Thanks in advance.
Alex.


Butterfly cannot run correctly
#2

Hi Alex,

Assuming your simulations has ran correctly (simpleFoamlog would tell us more about this) it appears to me that there might be a mismatch between the total iterations you allowed for the simulation and the interval for which probe values are saved. Try and have the second smaller than the first and you should see probe values there.

Another potential reason would be your surface being at the ground level, but I guess if you’re using the example file that would not be it (note to self: update the examples finally!).

Finally, it is much more interesting, and potentially useful for our applications to monitor/visualize wind velocities. Although when testing things working it doesn’t matter which you are trying to visualize.

Kind regards,
Theodore.


#3

Hi Alex, Theodore,

It seems I met the same problem as Alex describe, testing the example files following the tutorial video but got wrong results. I don’t really understanding how to have a smaller total iterations as Theodore mentioned, @Theodore, could you please share more details about this solution? Thank you so much!

Best regards,
GUO


#4

Thank you, @TheodorosGalanos !

The surface is raised 0.01m above GL. I tried to lift it higher, but there was no changes in the results.

Changing values in:
_endTime (controlDict)
_write interval (controlDict)
_interval (solution)
didn’t give any results neither.

The simpleFoam log is attached.
simpleFoam.log (501.9 KB)

Regards,
Alex.


#5

hi @ale_bog

could you try the example file and checking if you units in Rhino are in meter? let us know and please share the definition that creates the error for you.

Best,
Olivier


#6

Hi @OlivierDambron ,
I’m working on the example file already (the file’s attached)
01_0_outdoor_airflow.gh (445.5 KB)

And the rhino is in meters.
Thank you.
Regards,
Alex.


#7

I tried you file. It works fine at my end. You only need to offset the probes from the buildings by some distance (Usually the smallest mesh size).


#8

You can try following example file Outdoor_CFD.gh (506.7 KB)


#9

@devang the same thing happens to another file. Results are 0 :frowning_face:

Still can’t figure out, what’s going wrong on my computer.
Thanks for the attention to the issue.


#10

hi @ale_bog

I’ve noticed two things where butterfly remains needy: the syntax of the vector direction and the refinement levels.

Changing this worked

best,
Olivier


#11

Sorry for the late reply, thanks @OlivierDambron for stepping in!

I would also advise to assess these things a bit higher from the ground layer, at 0.01m it will almost always show smth near 0. A typical height for pedestrian comfort and the human domain is between 1.5-1.75m.

Kind regards,
Theodore.


#12

Thank you, guys for the comments.
However, I tried to rise the test area at various heights and nothing happened.
I’ll be in Melbourne for the airflow workshop this weekend, hopefully will get a better understanding of the process and will be able to fix the thing.

Regards,
AB.