Why can‘t create a wind tunnal

any chance to send the gh file…?

01_0_outdoor_airflow.gh (439.7 KB)
it is the example file,but i can’t run

if you right-click on the bounding box (at the moment set as ‘per object’) and you tick “union box”, it becomes a ‘union box’ and you should be able to visualise the tunnel, and apply the Brep Wireframe to see better what’s going on. It worked to me on your file.