Simulation and experimental validation of the motion of immersed rigid bodies in viscous flows

In this work we present the numerical analysis of the motion of a rigid body immersed in a viscous fluid. The fluid flow induced by the gravity-driven motion of a rigid body is particularly analysed using cylinders and spheres. The Navier–Stokes equations coupled with the interface motion are solved in the framework of a finite element formulation. The interface of the rigid body is represented using a moving Lagrangian interface technique (MLIT). The proposed formulation is applied to describe the two-dimensional motion of a cylinder between parallel walls as well as the axisymmetric representation of a sphere assessing in both cases the effects of the walls distance on the velocity developed by such bodies. The numerical predictions are verified using different models for the analysis of the problem, and are validated by comparison with theoretical–empirical correlations. Moreover, the computed body velocities are compared with experimental data reported in the literature as well as measurements obtained from experiments carried out in the framework of the present work.