Numerical investigation of vortex-induced vibration of a riser with internal flow

Vortex-induced vibration (VIV) of a riser considering both internal and external flows is investigated numerically. The model is firstly verified based on the comparison of the experimental data and numerical results. Then the internal flow is taken into account while VIV of a riser subjected to external flow in the subcritical regime of the Reynolds number is studied. Correspondingly, typical VIV characteristics such as the dominating mode and frequency in the in-line (IL) and cross-flow (CF) directions are analyzed, as well as the Root Mean Square (RMS) of the amplitudes, standing and traveling waves for the IL and CF responses. The results indicate that the IL and CF dominating modes are obviously influenced by the internal flow while the dominating frequency and RMS in both IL and CF directions are slightly changed during the investigation. The dominating modes for both IL and CF responses increase with the internal flow velocity increasing. Moreover, conspicuous traveling wave response is detected for both IL and CF responses while the internal flow interacts with the external flow for VIV.