An insight into the wake evolution of power-law flow past three tandem circular cylinders.

This paper reports the wake flow evolution of power-law flow past three tandem cylinders with identical diameter and spacing at a low incoming Reynolds number of Re = 80. The flow characteristics of power-law fluid with variable power-law index n are examined at spacing ratios of L/D = 3, 5, and 8 (where L is the spacing between the centers of two adjacent cylinders and D is the cylinder diameter). Three combined wake interference regimes are identified, including the overshoot-overshoot, overshoot-alternate reattachment, and alternate reattachment-quasi-co-shedding regimes, which are distinctly illustrated from the dynamic mode decomposition results. The quasi-co-shedding regime mainly occurs between the middle and downstream cylinders (denoted as C2 and C3, respectively) when L/D = 5 and L/D = 8. The switching of wake regime contributes to the sudden changes of hydrodynamic coefficients of the cylinders. Nevertheless, due to the shadowing effect, the drags of C2 and C3 remain to smaller than that of the upstream cylinder (denoted as C1). [ABSTRACT FROM AUTHOR]