A Strong FSI Coupling Scheme to Investigate the Onset of Resonance of Cylinders in Tandem Arrangement

This paper considers numerical simulations of two-dimensional viscous flow past oscillating cylinders using an efficient, oscillation-free, Cartesian grid based Immersed Boundary Method (IBM). The direct forcing approach originally developed by Uhlmann [1] for fixed and moving boundaries is employed. The IBM utilizes an improved smoothing technique for the discrete delta function and a solid-domain forcing strategy. A strong-coupling scheme is employed in which both, fluid and structure, are treated as linked components of a single dynamical system and all governing equations are iterated until convergence within the same time step. The accuracy, validity and efficiency of the utilized IBM are demonstrated by a series of validation cases including Vortex Induced Vibration (VIV) of an elastically mounted single cylinder and VIV assessment of a pair of cylinders in tandem arrangement. The method provides a good estimation of the single cylinder vortex lock in regime and fairly accurate predictions of the wake interference effect on the onset of resonance in flows involving multiple cylinders in an in-line arrangement.