Buoyancy of floating objects

The benchmark case of the buoyancy-driven motion of an unrestricted rigid body allows for experimenting new computational approaches for the more general case of fluid-solid interactions, in the case of solid objects larger than the smallest flow scales. The model is shown to respect free stream consistency, the correct dynamics of a buoyant body, for a range of positive and negative relative densities and the correct recovery of equilibrium states.

Unsteady motion of bodies through a free surface: Experimental measurements were performed on a glass sphere with D=0.012m, placed over a 0.20 m water column, half submerged and with density ρ=2.54ρw. The sphere is kept in place by a suction device and upon its release, a 500 Hz high speed records its position until it touches the bottom of the reservoir. First figure offers a comparison between the raw experimental data and numerical solution, plotted with the velocity field. Figure on the bottom details the evolution of the position and velocities of the sphere.


More information in: 

Canelas RB, Domínguez JM, Crespo AJC, Gómez-Gesteira M, Ferreira RML. 2015. A Smooth Particle Hydrodynamics discretization for the modelling of free surface flows and rigid body dynamics. International Journal for Numerical Methods in Fluids, 78: 581-593. doi: 10.1002/fld.4031.