화학공학소재연구정보센터
Journal of Rheology, Vol.46, No.3, 749-759, 2002
Sedimentation of a sphere in a suspension of neutrally buoyant fibers
The sedimentation of a dense sphere in a suspension of neutrally buoyant non-Brownian fibers is investigated experimentally. We consider in particular the effect of the ratio of the sphere diameter D to the fiber length L on the extra drag force experienced by the sphere in a broader range than in previous studies reported in the literature. For a given fiber concentration, the drag coefficient is found to be a strong function of the sphere diameter to the fiber length ratio, particularly when the ball diameter is on the order of the fiber length. When the ball diameter is increased, the drag coefficient rises, passes through a maximum for D = O(L), and then decreases to a steady state value for large spheres. Our experimental results are in qualitative agreement with the numerical simulations of Harlen et al. (O. G. Harlen et al., J. Fluid. Mech. 388, 355 (1999)].