This example combines a number of important DOPs concepts.
First, it uses both POP Solver and RBD Solver objects interacting with each other in a bidiretional manner. The RBD object affects the particles, and the particles affect the RBD object.
Second, the RBD object atually uses a multi-solver to combine an RBD Solver with a SOP Solver. The RBD Solver controls the motion of the overall object, while the SOP Solver performs the denting of the geometry.
Third, the SOP Solver extracts impact information from the RBD Solver to perform the denting. It extracts this information using DOP expression functions.
The end result is a simulation of a torus that is bombarded by a stream of particles. The particles bounce off the torus, and also cause the torus to move. In addition, each particle collision causes a slight denting of the torus.