Numerical analysis of factors influencing freely falling annular disks in an infinite fluid

Understanding path instability mechanisms of freely falling annular disks is a complex fluid-structure interaction problem. It is well known that disk size, inertia, and surrounding flow properties play significant roles in governing trajectories and wake structures. These factors control the solid to fluid relative intensity, which in turn gives rise to path and wake instability. We present a numerical investigation of factors influencing the free-fall of annular disks. Combining kinetic and dynamic characteristics, three dimensionless parameters are taken into account: the inner and outer diameter ratio, the dimensionless moment of inertia, and the body/fluid density ratio.