CFD as a Design Tool for Hydrodynamic Loading on Offshore Structures

Time-domain numerical integration of the rigid body equations of motion is a popular choice for analyzing the global motions of a single or multi-module floating platform. Potential flow theory cannot accurately account for all the hydrodynamic forces on certain components of the platform. However, for practical analysis, these members can be modeled as Morison members in the time-domain simulations. Computational Fluid Dynamics (CFD) can be used to calculate Morison coefficients for the given flow conditions on the exact geometry of the member. This paper presents the results from CFD simulations performed on several individual components of a floating platform (like heave plates, truss members etc.,) in realistic environment conditions. The procedure used for extracting the linear and non-linear coefficients from the total calculated hydrodynamic force is also explained. Results from CFD are compared to existing published experimental results. Differences between full-scale and model-scale results will be emphasized where important. Some of the advantages of using CFD as opposed to model tests are highlighted.