An efficient interface between the hydrodynamic and structural model, is a critical element in hydro-structure analysis of floating bodies. Main difficulties are related to the fact that two types of meshes (hydrodynamic and structural) are not the same due to the different criteria in mesh generation. In this paper we discuss the methods which are able to treat efficiently all aspects of the hydro-structure interactions in the linear seakeeping. Both the classical rigid body case and the hydroelastic case are considered. The hydrodynamic model is made under the potential flow assumptions and Boundary Integral Equation (BIE) method based on the so-called source formulation, is used to solve the corresponding Boundary Value Problems (BVP). Only the frequency domain approach is discussed.
In order to illustrate the main differences between the hydrodynamic and structural meshes, in Figures 1 and 2, we present the typical structural and hydrodynamic meshes for the container vessel. As we can see the meshes are significantly different. The hydrodynamic mesh contains only the panels below the mean waterline and is finer close to the waterline, while the structural mesh closely follows the different structural elements without "taking care" of hydrodynamics.
The first point is rather obvious, but the second one is slightly more unusual and concerns the hydroelastic interactions which will be discussed in more details later in the text. Briefly speaking, they are necessary in order to associate the hydrodynamic coefficients (excitation, added mass, ..) to the deformable modes of body motions.
Due to the differences between the hydrodynamic and structural meshes, an efficient interfacing procedure is needed in order to properly transfer the hydrodynamic pressure onto the structural model. Most often, diferent interpolation scheme are used but they appear to be neither robust nor efficient for general 3D cases.