Influence of varying inertia coefficient and wave directionality on TLP geometry

Offshore Tension Leg Platforms (TLPs) are extensively used for petroleum extraction in deep sea. Response behavior of TLP under hydro-dynamic loading is nonlinear due to large structural displacements and fluid-structure interaction. This study focuses on influence of two imperative parameters namely inertia coefficient and wave directionality on its geometry. Paper develops a mathematical formulation for non-linear variation of hydrodynamic inertia coefficient (Cm) along the water depth to yield optimum force on TLPs as well as influence of wave directionality on their geometric configuration while discussing the method of solution. Hydrodynamic forces are obtained from modified Morison equation while water particle kinematics is derived from Stokes’ fifth order nonlinear wave theory. Responses are obtained for two configuration of TLPs namely square and equivalent triangular TLP with total initial pretension same as that of square.