Internal flow effect with non-uniform temperature environment on VIV of marine risers under external shear current

Vortex-induced vibration (VIV) of marine risers under external currents may cause serious fatigue damage, which is a challenging issue especially when the internal flow is included simultaneously. The temperature gradient between the conveying fluid and the surrounding seawater makes the internal flow effect more complicated. In this paper, the effect of internal flow with a non-uniform temperature environment is added to the riser’s dynamic governing equation, and the semi-empirical model is adopted to simulate VIV. A large number of cases are designed to analyse the dynamic response and fatigue damage of the riser when the internal flow and non-uniform temperature environment are individually considered. Then, the combined effect of the internal flow and temperature environment is compared with the simple superposition of their individual effects. The increase in the internal flow temperature could trigger mode jump and enlarge the fatigue damage.