Alam, Md. MahbubMeyer, Josua P.2013-10-152013-10-152013-08Alam, MM & Meyer, JP 2013, 'Global aerodynamic instability of twin cylinders in cross flow', Journal of Fluids and Structures, vol. 41, no. 8, pp. 135-145.0889-9746 (print)1095-8622 (online)10.1016/j.jfluidstructs.2013.03.007http://hdl.handle.net/2263/32054This 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.en© 2013 Elsevier. All rights reserved. Notice : this is the author’s version of a work that was accepted for publication in Journal of Fluids and Structures. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Fluids and Structures, vol. 41,no. 8, 2013, doi : 10.1016/j.jfluidstructs.2013.03.007ForcesFlow structuresAerodynamic loadShear flowLift (Aerodynamics)Cylinders -- AerodynamicsCylinders -- VibrationFluid dynamicsPostprint Article