Wake-Induced-Vibrations of Circular Cylinders in Tandem Arrangement

Abstract

Stabilized space-time finite element technique is utilized to perform numerical simulation on the wake-induced-vibrations of two identical tandem circular cylinders placed in the flow at Reynolds number 100. Cylinders are separated by a center to center distance of 5 times the diameter of the cylinder. Results are computed for various values of reduced velocities (1 to 8). The downstream cylinder, of mass ratio 10, is allowed to execute oscillations in both in-line and transverse directions, whereas the upstream cylinder is stationary. Response curve of downstream cylinder is observed to be composed of initial and lower branches. Phenomenon of lock-in is identified at a reduced velocity of 5. Nature of flow exhibits periodicity for the entire range of initial branch with single dominant lift frequency. For reduced velocity near the end of lock-in, flow and body motion shows quasi-periodic behavior with complicated non-overlapping loops in the cylinder trajectory as well as in the phase plots of drag and lift coefficients.

Keywords: Circular Cylinders, Periodic and Quasi Periodic Flow, Tandem Arrangement, Two Degree-of-Freedom, Wake Induced Vibration