The motion of a rotating circular cylinder in a stream of Bingham plastic fluid

Abstract

In this work, two-dimensional, steady flow of incompressible Bingham plastic fluids past a rotating circular cylinder has been studied. The continuity and momentum equations have been solved numerically over the range of conditions as follows: 0.1 ≤ Re ≤ 40; Bingham number, 0 ≤ Bn ≤ 103 and non-dimensional rotational velocity 0 ≤ α ≤ 5. The objective of the detailed numerical study is to elucidate the effects of Reynolds number, Bingham number and rotational velocity on the yield surfaces, the drag and lift coefficients, and torque acting on the rotating cylinder. The present drag results have been correlated with the modified Reynolds number and rotational velocity to interpolate the intermediate values of Bingham number. In additional, shear rate and yielded/unyielded contours, and streamlines in the vicinity of the cylinder are also presented for detailed visualization of the flow field. The critical Bingham number, denoting the cessation of the flow detachment from the surface of the rotating cylinder, has been plotted as a function of the Reynolds number, and the rotational velocity is shown to suppress the propensity for flow separation.