Quasi-Static Fluid Structure Interactions for Ship Advancing in Waves With Constant Forward Speed

Evaluation of structural stresses for ships advancing with constant forward speed U in waves, represents a particularly important practical problem. Depending on the wave conditions and the structural properties of the ship, different types of fluid structure interaction procedures might be needed to evaluate these stresses. In the present work, the accent is on the so-called quasi static structural response which is relevant when structural vibrations are not likely to occur. Due to relatively high structural natural frequencies of the hull structure, when compared to wave frequencies, the quasi-static structural response is most often of major practical concern. The exceptions are some particular problems such as for example whipping where the structural vibrations might occur due to important impulsive loading induced by slamming or other sources. For those cases, a more complex coupling procedures, based on full hydro-elastic coupling principles, are necessary. These issues are not discussed here but will be considered in the future. Within the quasi-static assumptions for the structural response, the main technical difficulty concerns the pressure transfer from the hydrodynamic model to structural model. In the present work, Boundary Integral Equation Method (BIEM) is used to solve the hydrodynamic problem and the Finite Element Method (FEM) is used to solve for the structural response. When compared to the seakeeping problem without forward speed, the solution of the hydrodynamic Boundary Value Problems (BVP) is much more complex and the different coupling strategies are required.