Hashem Moradi

A hydroelastic hybrid model is developed to simulate the fluid–structure interaction in water entry problems using the partitioned approach. The interactions between a flat plate and the water are modeled by a hydroelastic model using explicit and implicit couplings. Both couplings are unstable due to numerical instability associated with the fluid added mass. To overcome the instability, an extended Wagner’s model is combined with the hydroelastic model, and a hybrid model is developed. The extended Wagner’s model is the extension of the classical Wagner’s model that is used to estimate the fluid inertial, damping, and restoring forces of a flexible plate within the potential flow theory. The fluid flow is described by the unsteady Reynolds averaged Navier–Stokes equations in the hydroelastic model and hybrid model. The longitudinal bending of the plate is approximated by the strips in all models. The hybrid model is verified and validated by comparing the available computational and semi-analytical results of the vertical and oblique water entries for the plate with different boundary conditions. The results show that the hybrid model is stable, accurate, and simple to implement. This two-dimensional model can be generalized to the third dimension and applied for more complex structures.