Fluid structure interaction simulation of subaqueous spherical objects: Soft sphere collision

Sustainable sediment transport management is one of the big challenges in river engineering regarding hydraulic structures and environmental conservation. The mechanics of sediment transport still require a lot of research. In bedload sediment transport, the motion of about 30% of moving particles is initiated by near field interactions and collisions. Thus, collision models for these types of interactions among the sediment particles are required.

To simulate such collisions, we implemented a soft sphere collision model with a lubrication model in the context of the immersed boundary model within our in-house and openly available code, i.e., the so-called Virtual Flow Simulator (VFS-Geophysics) model. The implemented collision model was validated according to available data of collision experiments and used to simulate colliding subaqueous spherical pendulums, showing good agreement with experiments done in our hydraulic laboratory.

Allowing for more general shapes in future development, the collision detection was implemented with different possibilities to compute contact points on the objects surfaces and their distance, e.g. spheres, oriented bounding boxes, and convex distance calculations.