Large Eddy Simulation of Fluid-Elastic Instability in Square Normal Cylinder Array

Large Eddy Simulations (LES) are performed at low Reynolds number (2000 upto 6000) to investigate the dynamic fluid-elastic instability in square normal cylinder array for a single-phase fluid cross flow. The fluid-elastic instability is dominant in flow normal direction, at least for all water-flow experiments (Price et al. [18]). The instability appears even in the case of single moving cylinder in an otherwise fixed-cylinder arrangement resulting in the same critical velocity (Khalifa et al. [1]). Therefore, in the present work only a central cylinder out of 20 cylinders is allowed to vibrate in flow normal direction. The square normal (90°) array has 5 rows and 3 columns of cylinders with 2 additional side columns of half wall-mounted cylinders. The numerical configuration is a replica of the experimental setup except for the length of cylinders, which is 4 diameters (4D) in numerical setup against about 8D in the experiment facility. The single-phase fluid is water. The standard Smagorinsky turbulence model is used for the sub-grid scale eddy viscosity modeling. The numerical results are analysed and compared with the experimental results, for a range of flow velocities in the vicinity of the instability. Moreover, instantaneous pressure and fluid-force profiles on the cylinder surface are extracted from the LES calculations in order to better understand the dynamic fluid-elastic instability.