Hello all. I'm currently trying to model (roughly) the effect a stent would have on blood flow into an aneurysm, and I ran into a problem with the flow simulation where it says I have zero volume. The model is attached.

When I run a fluid analysis on the assembly without the stent, everything works just fine and I get a non-zero fluid volume when I check the assembly's geometry, as shown in the first picture. However, when I put the stent into the assembly and checked the geometry, the fluid volume shows up as zero (second picture). Any idea what could be going on? At first, I thought it was because the stent's position was under-defined, but after adding a lock mate to fix the stent's position, the result is the same--zero fluid volume.What could the stent be doing that is making the model not work?

Any help is greatly appreciated! Thank you.

Pictures: