KevinL Thanks for giving Ziva VFX a go!
You should be able to achieve the effect you are after, but it will require a few more steps.
If I were to do it, I would do the following:
- Rig your character as you normally would (joint hierarchy, skinCluster . . .)
- Duplicate the character mesh twice (we'll refer to them as "A" and "B")
- Fit a sphere to the area of the belly (it will likely work best, if the fit sphere extends beyond the area you want to jiggle, so that you have some additional surface space to blend the result back into the skinClustered mesh.
- Select the sphere and then execute: Ziva->Tissue
- Select the skinClustered character and execute: Ziva->Bone
- Select the vertices at the back of the sphere (on the inside of the character) and shift select the skinClustered character and execute: Ziva->Attachment
- Select the sphere object and the shift select "A" then execute: Ziva->Embedded Mesh
- Select the skinClustered character and then shift select "B" and execute: Deform->Blend Shape and set the shape to 1.0
- Select "A" and then shift select "B" and execute Deform->Blend Shape and set the shape to 1.0
- Flood the blendShape2 deformer weights to 0.0 and then pain in the area that you would like to be affected by the simulation.
I hope that is clear - it is quite a few steps (probably something we should consider simplifying!)
Let me know if you require any additional clarity.