Detached eddy simulations of flow induced vibrations of circular cylinders at high Reynolds numbers

This work presents a development of computational fluid dynamic model for numerical simulations of flow induced vibrations, important physical phenomena characterizing operations of various engineering structures, especially offshore installations including risers and platforms. We propose an application of detached eddy simulation (DES) approach for simulations of incompressible Navier-Stokes flows over cylindrical structures coupled with its rigid body motions. In this approach, a hybrid turbulence model based on Reynolds average Navier-Stokes (RANS) and large eddy simulations (LES) is implemented for modelling of high Reynolds number flows over free oscillating cylinders where near wall flow features are modelled with RANS and LES is employed for resolving wake dynamics. The proposed approach is validated against several experimental set ups of fixed cylinder as well as cylinders under vortex induced vibrations. A straightforward implementation of the proposed DES approach provides more reliable and accurate numerical results than traditional URANS for high Reynolds number flows in predictions of forces acting on cylinders and their responses. Numerical experiment using the presented approach for cylinder with single degree of freedom (cross flow oscillations) and two degree of freedoms (in-plane oscillations) shows that it is able to capture VIV fundamental characteristics and predict accurately responses of cylinders at various reduced velocities and mass ratios. Numerical prediction is in good agreement with earlier experimental studies for presented benchmark test cases. It shows a great potential of the proposed approach for design and analysis of structures under flow induced vibrations.