Improving boundary conditions for Lattice Boltzmann simulations of fluid-induced forces on non-spherical particles at high Reynolds numbers
Sedimentation and centrifugation are widely used to fractionate particles based on their size or density differences, for example the sorting of nanoparticles and the recycling of battery materials. For these processes, predicting how an initial size distribution evolves in time when subject to a gravitational or centrifugal body force is essential yet still a considerable challenge due to the long-range hydrodynamic interactions between particles. In this projects, multiscale numerical simulations are carried out to study the sedimentation of polydisperse suspensions, including continuum modeling and discrete particle modeling. In particular, we focus on particles with log-normal size distributions as they are ubiquitous in engineering, environmental and biological systems as a result of repetitive particle breakup processes.
In the first part of this project, a 1D continuum model is used to study the evolution of size distribution over time in the very dilute limit, focusing on the multi-step sedimentation, in which the supernatant and sedimented layers are removed and sedimented in successive steps with the goal of fractionating in size classes with as little impurity as possible. In the second part of this project, 3D discrete particle simulations are done using Stokesian dynamics to quantify the effect of hydrodynamic interactions at finite volume fractions, including the hindered settling and hydrodynamic diffusion of each size class during sedimentation. The outcome of this project will be useful to design more efficient sedimentation processes for fractionation of particles.
Multicascade centrifugation for fractionation of nanosheets and illustration of size pdf evolution during this process.
