Hydroelastic analysis of bodies that enter and exit water

The entry and exit of flexible bodies through an air–water interface is studied using a tightly coupled fluid–structure interaction solver. The fluid domain is modeled using finite-volume CFD and the flexible structure is represented by a modal basis. The current work uses finite elements to generate the structural mode shapes and frequencies. The modal description allows for a reduction in structural degrees of freedom to reduce computation time. A linearized boundary condition is used on the mutual interface to eliminate mesh deformation. The accuracy of the method is quantified using the constant-velocity-wedge-impact problem. The quality of the fluid solution for the entry and exit problem is evaluated using a rigid wedge case and comparison to Von Karman and Wagner theories. Finally, the response of an elastic wedge during entry and exit is studied with the fluid–structure interaction solver. The results are used to assess two common approximations, namely the rigid-quasi-static and rigid-dynamic approximations. It is shown that for entry and exit, hydroelastic effects may be important for a wide range of loading conditions.