Effect of porous media on wake-induced vibration (WIV) in tandem circular cylinder

Abstract

In practical engineering, cylindrical structures are frequently arranged in tandem under different flow environments. In this study, wake-induced vibration (WIV) of a solid circular cylinder in the wake of a stationary porous cylinder is numerically investigated. A numerical model including the porous medium and vibration modules is established by using the Immersed Boundary (IB) method and the calculation accuracy of the model is verified by the experiment. Seven porosities of the upstream cylinder from 0.0 to 1.0 are considered and the downstream cylinder is allowed to oscillate in both streamwise and transverse directions. The effects of the gap between the two cylinders, the Reynolds number (Re) and the reduced velocity (Ur) on the upstream-stationary-downstream-vibrating tandem cylinders are investigated in terms of shear layer reattachment, vortex impingement and wake interference. The wake flow pattern and the vortex shed from the porous cylinder are vulnerable to the porosity of the cylinder. As a result, the vibration of the downstream cylinder caused by the wake changes at different porosities. Besides, the hydrodynamic force and vibration frequency are also tightly associated with the wake interaction. At different reduced velocities (Ur) and Reynolds numbers (Re), the WIV and the force on the cylinder change significantly.