I've been experimenting with creating cast resin objects lately. When I start thinking about what the mold should be for a particular object, I sometimes struggle to imagine how the resin would flow through the space. One particular shape, my 3D logo, had a lot of cavities where air bubbles could get trapped and ruin a casting, so I thought doing a fluid simulation in Houdini may give me some insights. It worked way better than expected!

The main setting you have to enable for a simulation like this to work is "Enforce Air Incompressibilty". That simulates the air being entrapped within the shape by the fluid. Bubbles have to form to transport the air from the deep cavities into the pour spout.

These simulations quickly and cleanly showed me the flaw in my design. I need to add some vent holes to allow the air to escape from the various pillars. This'll mean more work smoothing the surface after casting, but it's worth it considering how badly the mold would've performed otherwise.