URANS-Based Prediction of Vortex Induced Vibrations of Circular Cylinders

Vortex induced vibrations (VIV) are highly nonlinear due to three different frequencies involved in the process; fluid force frequency, vortex shedding frequency and oscillation frequency. It is computationally complex to solve such a chaotic fluid flow but recent progress in numerical algorithms, turbulence models and computer capabilities have made it easier to approach the problem with a nonlinear approach. These developments have paved the way to approach the problem with the simple equation of motion of Newton’s law and when coupled with URANS, which is a commonly used method in solving problems related to fluid flow, the highly nonlinear problem of vortex induced vibrations become solvable. The existing literature computationally can only handle flows for Re>10,000-12,000 but the numerical methodology adopted in this study furthers this limitation. The numerical algorithm is first tried for a stationary cylinder and the boundary layer separation is investigated for higher Re. The generated results are found to be satisfactory to proceed solving for VIV at high Re. The solution strategy is tested in a wide range of Reynolds number with different springs and damping coefficients. Satisfactory agreement is found with the experiments for a cylinder in VIV. The shortcomings of the computational work and why these limitations arise are tried to be explained using the experimental results and the existing mathematical models.

URANS-Based Prediction of Vortex Induced Vibrations of Circular Cylinders Keywords:

VIV , Flow around cylinder , Reduced velocity , Oscillation frequency , Spring stiffness