Flow between parallel walls containing the lines of neutrally buoyant circular cylinders

The motions of a single and two lines of neutrally buoyant circular cylinders in fluid between flat parallel walls are numerically investigated over the range of the Reynolds number of 12 < Re < 96, the ratio of the diameter of the cylinder D-s to the channel width D of 0.25 less than or equal to D-s/D less than or equal to 0.5, and the ratio of the streamwise spacing of the cylinders L to the channel width of 0.75 less than or equal to L/D less than or equal to 2, The lattice Boltzmann method is used for computations of the fluid phase and the cylinders are moved according to Newton's law of motion. The Segre-Silberberg effect is found for both a single and two lines of cylinders. It is also found that for two lines of cylinders with D-s/D = 0.25 and L/D = 1, the equilibrium positions of the two lines are arranged to be staggered with respect to each other in the flow direction. The effects of the Reynolds number Re, D-s/D, and L/D on the equilibrium position of the lines of cylinders and on the friction factor of the cylinder-fluid mixture are presented and discussed. (C) 2000 Elsevier Science Ltd. All rights reserved.