Unusually high velocities

grasshopper butterfly
1

Hello All,

I am trying to run an outdoor study using butterfly. The solutions run fine. The values I see however are totally unusual. Can somebody help please?

Windspeed
Windspeed.JPG1155×540 128 KB
outdoor.gh (578.2 KB)

2

@devang,
It looks like your solution has diverged because of poor meshing. One of the OpenFOAM gurus on the forum like @TheodorosGalanos can probably give you better advice than I but I would start by building your mesh differently. It looks like you have somehow meshed the inside of the buildings, which may be causing the issue.

3

Thanks @Chris,
I tried the outdoor example that ships with Butterfly. I updated the definition to run with the latest version of Butterfly on Github. I get the same results. Unusually high velocities.

Another question is, there’s an output on Butterfly_Meshing Parameter component named meshParams. where to use this? In the last stable release version, the Butterfly_Create Case from Wind Tunnel component had an input to receive these parameters I believe.

4

Remove the probes tat are located inside the building. Also see this:

5

Thanks a lot @mostapha,
Looks like this will definitely solve the issue. I will try this.

6

Also, the surrounding mesh is way too small… You’ll have to move the mesh boundaries much further away from the building geometry.

7

Thank you @AlbertPressler,
Could you share an example as to who to correctly model the surrounding mesh far from buildings please?

8

I assume the wind tunnel itself is much larger. Butterfly uses probes to visualize the results for any desired part of the domain. This is not a full section of the wind tunnel and only representing the area of interest to track the results.