Abstract

In this contribution we show how the phenomenological theory of sedimentation-consolidation processes can be extended to the presence of centrifugal field. The modelling starts from the basic mass and linear momentum balances for the solid and liquid phase, which are referred to a rotating frame of reference. These equations are specified for flocculated suspensions by constitutive assumptions that are similar to that of the pure gravity case. The neglection of the influence of the gravitational relative to the centrifugal field and of Coriolis terms leads to one scalar hyperbolic- parabolic partial differential equation for the solids concentration distribution as a function of radius and time. Both cases of a rotating tube and of a rotating axisymmetric vessel are included. A numerical algorithm to solve this equation is presented and employed to calculate numerical examples of the dynamic behaviour of a flocculated suspension in a sedimenting centrifuge. The phenomenological model is appropriately embedded into the existing theories of kinematic centrifugation processes of ideal (non-flocculated) suspensions. © 2001 Elsevier Science B.V. All rights reserved.