A simulation and experimental study on particle volume fraction of PMMA suspension in centrifugal fields

Abstract

A suspension of monodisperse PMMA spheres in sodium chloride solution carrier fluid in centrifugal field is numerically simulated and experimentally studied. We apply the continuum constitutive equation based on the diffusive flux model and the buoyancy terms. The resulting equation is solved with the finite element method in a simulation software. We simulate the particle sedimentation using this method with a focus on the settling zone under two cases of centrifugal forces. The settling zone is defined as the particle volume fraction φ breaks up to the maximum volume fraction φ_max and reach the equilibrium. This zone can be clearly seen by the yields point in radial position r. Based on this result, we develop a fitting model φ_fit to predict the particle volume fraction in radial position r of centrifugal fields’ G. We assess this fitting model φ_fit using the data of in situ measurement of particle sedimentation in decanter centrifuge by wireless electrical resistance detector (WERD) in the same suspension under high centrifugal force g. Next, the effective medium theory is used to measure the in situ particle volume fraction φ_exp of the experimental data. As a result, the particle migration is significantly induced by particle-concentration dependent. Under these conditions, we have found that the initial particle concentration is critical to matching the experimental result. However, the continuous supply of suspension measured in experimental study highly-influence the progressive increment of particle volume fraction in the settling zone. This explain on how the fitting model φ_fit only give a good agreement below five seconds of the particle sedimentation in centrifugal fields.