Effect of streamwise and transverse damping on flow around an elastically supported cylinder

In this paper flow around a circular cylinder free to move in two-degrees-of-freedom is investigated numerically in the Reynolds number range of Re=80–240. Reynolds number is varied with the reduced velocity U* using Re=34.74U* and the mass ratio is fixed at m*=10. The main purpose of the study is to investigate the effects of streamwise and transverse damping values (ζx and ζy). Computations are carried out for different Re and U* pairs to investigate the separate effects of ζx and ζy. Although ζx has a negligible effect on flow parameters, at small transverse damping values a significant increase is identified in the mechanical energy transfer E and a substantial drop occurs in the root-mean-square and time-mean values of drag (CDrms and CDmean). Energy transfer is influenced mainly by transverse cylinder motion. Changes in the vortex structure are also identified. In addition, computations are carried out for different ζy (ζx=0) values with varying Re and U*. Two-branch cylinder response and small E are observed for ζy=0.001 while high E is observed at larger but still low ζy values. At high ζy all quantities investigated become small. CDrms and CDmean curves plotted against Re shift downwards with increasing ζy.