Exploratory Free Standing Riser VIM Model Tests

An exploratory research model test campaign was undertaken to study the vortex induced motions for a range of current speeds between 0.16 and 3.3 m/s. The model was constructed at scale 1:68.75, with the vertical riser truncated at 375 m water depth. Two different weights of the vertical riser were considered. The tests were carried out in a large towing tank (8 m deep, 18 m wide and 240 m long), ensuring uniform flow conditions. Mode 1 response was observed for small current speeds, with a normal ”figure-of-eight” type trajectory of the air can. At higher speeds, the response became more complex with participation of higher modes and irregular wake-induced motions.