Hydrodynamic Coefficients of a Flexible Pipe With Staggered Buoyancy Elements and Strakes Under VIV Conditions

A 38m long flexible pipe with staggered buoyancy modules and strakes has been tested in the ocean basin of SINTEF Ocean (former Marintek) for VIV investigation of a lazy wave riser. In this paper the inverse analysis method was presented and applied into the investigation of the hydrodynamic force coefficients along this tested flexible pipe with the measured responses as inputs. The feasibility of the inverse analysis method is firstly validated by numerical simulations. The distributions of the added mass and excitation coefficients along the flexible pipe with staggered buoyancy modules and strakes are then investigated. The identified coefficients are validated by check of the natural frequencies and responses of the model, and are finally compared against those from the forced oscillation tests.