An Analytical Model of the Effect of Internal Density Waves in Risers Subjected to Vortex Shedding

Abstract

Risers used for deep sea mining will be subjected to vortex-induced vibrations (VIV) caused by ocean currents. The internal flow, consisting of e.g. mineral ore and water, will have a non-uniform density. This traveling density wave may influence the dynamic response of the riser. In this paper, a simplified analytical approach is adopted to estimate the disturbance caused by the internal flow. The analytical model predicts a large disturbance (resonance) at a certain critical wavelength, which is verified by numerical simulations.