Abstract:
This paper comprises an in-depth physical discussion of the flow-induced vibration of two circular
cylinders in view of the time-mean lift force on stationary cylinders and interaction mechanisms. The
gap-spacing ratio T/D is varied from 0.1 to 5 and the attack angle a from 0¡ to 180¡ where T is the gap
width between the cylinders and D is the diameter of a cylinder. Mechanisms of interaction between two
cylinders are discussed based on time-mean lift, fluctuating lift, flow structures and flow-induced
responses. The whole regime is classified into seven interaction regimes, i.e., no interaction regime;
boundary layer and cylinder interaction regime; shear-layer/wake and cylinder interaction regime;
shear-layer and shear-layer interaction regime; vortex and cylinder interaction regime; vortex and
shear-layer interaction regime; and vortex and vortex interaction regime. Though a single non-interfering
circular cylinder does not correspond to a galloping following quasi-steady galloping theory, two circular
cylinders experience violent galloping vibration due to shear-layer/wake and cylinder interaction as well as
boundary layer and cylinder interaction. A larger magnitude of fluctuating lift communicates to a larger
amplitude vortex excitation.
