Vortex induced vibrations on circular structures: Numerical modeling of aerodynamic loads

The analysis of the complex flow around circular cylindrical structures such as chimneys is of significant importance for the design of the structure. Special  attention needs to be paid to the aerodynamic forces impacting the structure in the across-wind direction due to vortex induced vibrations. Here, the aeroelastic  interaction between the fluid and the structure can lead to large amplitudes of motion of the structure. The appropriate prediction by numerical simulation of the different Reynolds number dependent characteristics of the flow, such as the shedding of vortices, the transition from laminar to turbulent flow in the wake and  the shear layer is an arduous task. By including fluid-structure interaction such as the lock-in phenomenon the flow becomes even more complex. Therefore, this work analyses the influence of various simulation methods on the aerodynamic and aeroelastic parameters. First, the flow around a static cylinder is explored, outlining the differences between the different numerical approaches. Additionally, the numerical methods are used to explore vortex induced vibration in the lock-in region based on forced oscillation simulations with small amplitudes of motion.  The prediction of the numerical simulations of the aerodynamic parameters are validated against wind tunnel measurements to determine the optimal numerical methods. All numerical simulations are carried out at a Reynolds number of 2.3*104 with the OpenFOAM version 4 software package.