xue yue

I just used a packed fractured object and v@v instead of v@vel (which is the name for velocity volumes).

Also v@P.y is not the centroid, it is the y-position of every Point your wrangle runs on. If you need to do it without the packed object (which is slower than the packed sim) you can use the Extract Centroid SOP to get the centroid of every connected piece and use this instead v@P.y in the wrangle.

To be honest I don't understand what your issue is. But if you don't want the interior faces you can uncheck "Create Interior Surface" in the Voronoi Fracture SOP.

As for the "Unshared Edges", they are not detected, because there are none. In Houdini an "Unshared Edge" refers to an edge, that is not shared between different primitives or polygons. You can spot holes or corners on open geometry with that option, but not on voronoi shattered pieces. These are closed meshes usually (except you deactivate the option for interior surfaces mentoned above).

Hard to say what your specific issue is, but I'd argue that usually it has a reason. In the worst case you can always set your simulations to on/off (the brain icon) or the dropdown to manual update (lower right corner of Houdini). You then would have to enable it again when you need the simulation data.

It could also be, that you are inside a geometry network, but your view is set to "Show All Objects" (top right of the scene view) and this shows everything in the main obj network where data from after your sim could be linked.

Hope that helps