Buoyant ellipsoidal particles at high Galileo numbers

Large and buoyant ellipsoidal particles display path instabilities at sufficiently high Galileo numbers due to the break-up of the wake symmetry. Using direct numerical simulations with the immersed boundary method, we analyse the dynamics of a freely rising buoyant particle by varying its aspect ratio over a range of Galileo numbers. The density ratio of the solid particle to the fluid phase is held constant. The study employs a single buoyant particle in an opposing counter flow. For a fixed particle Reynolds number, we set the flow conditions such that the net buoyancy force on the particle balances its drag. We link rising modes to the particles’ Galileo number and analyse the rise velocity for various particle shapes and aspect ratios.