Revolving flow of a fluid-particle suspension with suction

The three-dimensional revolving flow of a particle-fluid suspension above a plane surface is considered. The flow represents an extension of the classical Bodewadt flow to a two-fluid problem. The governing equations for the two phases are coupled through an interaction force with the particle relaxation time tau as a free parameter. By means of a similarity transformation, the coupled set of non-linear ODEs becomes a two-point boundary value problem. The numerical results show that the radial inward particle velocity increases whereas the circumferential velocity decreases by shortening tau, thereby strengthening the spiralling particle motion. These predictions are consistent with the so-called tea-cup effect, i.e. accumulation of tea leaves at the centre of the cup. On the contrary, the revolving fluid motion is reduced as a result of the particle-fluid interactions. (C) 2017 Faculty of Engineering, Alexandria University. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).