Simple urban wind results comparison - Butterfly with Autodesk CFD



I am comparing results from Butterfly with those from Autodesk CFD. I created a simple urban wind model and ran both simulations with a base wind speed of 5 m/s. The buildings range in height from 10-20m. The results are displayed on a 3x3m grid, with a coloured mesh showing wind speed and white arrows showing direction.

The wind patterns seem quite similar, but there is an obvious difference in wind speed between the two simulations. I’ve inspected the meshes and they both are of good quality. Does anybody have any ideas about the difference in behaviour? It seems strange that the Butterfly results show such a low wind speed at the entrance of the tunnel (around 2 m/s), shouldn’t this be 5 m/s?

Any help would be much appreciated!! Let me know if you need more details :slight_smile:

Kind regards,



Hi @nicholas

It’s really hard to say with the information provided. Mesh being ‘good quality’ is not enough for a comparison, it has to be identical in some way.

I would suggest to try and align all parameters between the model, mesh type, mesh size and refinement, wind tunnel dimensions, ground roughness, boundary conditions, incoming wind profile, turbulence model, and so on.

After that, you can run a comparison study and be a bit more certain of the results. If all or some of this is already aligned please let us know.

Kind regards,


Hi Theodore!

Thanks for such a quick response! I will check through the parameters in more detail and get back to you :slight_smile:



@nicholas and @TheodorosGalanos,
I remember those times that i tried to use AutodeskCFD and was so surprised and disappointed that to create/define the wind profile it needs to be done manually, literally, moving points in a profile scale on the software. Needless to say that this is an impossible mission. At that point i stopped my trials with this software.
It was a couple of years ago and suspect they didn’t implemented any more scientific solution to the issue. If they don’t, so there is nothing to compare here, sadly.
Maybe you know?


@AbrahamYezioro yes I’ve just experienced the same thing! After making this post I read that Butterfly automatically creates a logarithmic wind profile, so I’ve been trying to reproduce the same profile manually in Autodesk CFD. :expressionless:


As @TheodorosGalanos and @AbrahamYezioro noted Butterfly takes the input wind speed at a specific height (10 meters by default) and generates the wind profile. It makes sense to have a lower wind speed in a lower height. It seems in your study Autodesk CFD generates an inlet with a uniform wind speed.