Very low wind results in paraview - box bounded

Hi All,

I’m trying to run outdoor wind analysis with butterfly. I ran only 5 to 10 solutions to see if the vectors are more or less in the right range, but when I cut a slice in paraview I only get blue colour meaning 0 U-magnitude and there seems to be a darker blue box bounding the buildings area. Any idea what’s going wrong?

In the below image i’m using the example file and the outdoor airflow script.

hi @Farah.H,

Your legend’s highbound is set to 8.5 m/s, you can try to lower it.
Also you are visualizing the first timestep of your simulation, I can see you have 4, try the 4th and see if the fluid is more developped.
Furthermore, thedarker blue corresponds to your refinement region. All cells in that region are more subdivided /finer. Meaning that your slice reads results more accurately where the mesh is finer while outside the bounding box, the slice reads the value from larger cells which can be representative of values located higher or further… this is quite hard to explain… here’s a quick diagram.

In section, the horizontal line is your section plane, the dots where values are read, and the jump between the size of the cells is where your refinement region ends. So essentially the values of the closest points are projected onto the section plane to visualize results. if your grid is not subdivided in a more regular way you will have big jumps of results.

You can look into Grading the mesh along x y and z axis.

best,
Olivier

Hi @OlivierDambron, many thanks for your reply and explanation.

i’ve just tried time-step 4 and this how it looks like, not sure why only around the refinement region changes…