Liquid fluidization of short hollow cylinders

We perform numerical simulations on fluidized dense suspensions of solid spheres, solid cylinders and hollow cylinders in a Newtonian liquid. The simulations are three-dimensional and time dependent and aim to resolve the flow around and – for the hollow particles – inside individual particles. We use a lattice-Boltzmann scheme that includes an immersed boundary approach for imposing no-slip at solid surfaces. The overall solids volume fraction is 0.5 for the solid particles and 0.375 for hollow cylinders. The latter have a length over outer diameter aspect ratio in the range 0.56 to 1.58 while the ratio of outer to inner diameter is 2. Archimedes numbers of the order 103 to 104 are such that we expect in homogeneous fluidization with wave-type voidage instabilities. We have a particular interest in the flow through the inner diameter of the hollow cylinders and the extent to which it could contribute to liquid solid mass transfer.