Wind Shielding Estimation of a Tandem Vessel Using Disturbed Velocity Field from CFD

The wind forces experienced by a receiving transport vessel in a tandem configuration will be influenced by so-called shielding effects, caused by the distorted wind flow field in the wake of an FPSO (Floating Production Storage and Offloading vessel). Therefore, it is important to include the shielding effects into the wind force assessments of the transport vessel in order for safe approach and offloading operations. In earlier work a predictive wind shielding estimation model is developed using the measured shielded wind velocities after the FPSO and the measured unshielded wind coefficients of the transport vessel. In this paper, the same shielding model is adopted by using the wind coefficients and wind velocity field both obtained using Computational Fluid Dynamics (CFD) calculations. The transport vessel is divided into 4 segments for accuracy purpose. The volumetric mean wind magnitude and direction is calculated for each vessel segment volume. The unshielded wind coefficients for each segment of the transport vessel are also estimated using CFD calculations. The results from this shielding model compare well with those from wind tunnel model tests.