This paper presents dependence of forces and flow structures on phase lags between vortex
sheddings from three tandem cylinders. The flow around the three cylinders of an identical
diameter D is numerically simulated at a Reynolds number Re= 200 for spacing ratios L 1*=
L 1/D= 3.5-5.25 and L 2*= L 2/D= 3.6-5.5, where L 1 is the center-to-center spacing between
the upstream and middle cylinders, and L 2 is that between the middle and downstream
cylinders. The variations in L 1* and L 2* in these ranges correspond to the phase lags ϕ 1 …