Posted by Precise Simulation on
URL: http://forum.featool.com/Error-when-combining-objects-subtracting-object-from-flow-block-tp1633p1644.html

Following up, this issue is due to deduplicating boundaries for geometry object visualization (to save resources), in particular since here the scale difference of the object were quite large it became an issue with the current algorithm. However, the issue is just with geometry boundary visualization, so you can still mesh, and later show and set boundary conditions on the correct geometry. That said, from a simulation perspective it still might be better to have an inner finer block, with an outer coarser one, depending on the simulation. Thank you for submitting the issue report, a fix will be included in the next update later in the year.