Nonlinear analysis of bottom slamming on Pontoon-type VLFS

Pontoon-type Very Large Floating Structures(VLFS) are platforms with very large horizontal dimensions and limited drafts. The wave-side part of the bottom may get dry in realistic head sea wave conditions. Two main types of bottom slamming have been observed. One type involves an air cushion that occurs near the front edge. The other one occurs without air entrapment. A two-dimensional fully-nonlinear wave tank is applied to study the interaction between regular waves and the VLFS restrained from oscillating. The Boundary Element Method (BEM) is used to obtain numerical solutions. For both types of impact, bottom slam-ming can occur with a very small deadrise angle, a local analytical solution is coupled with the numerical method. Present results are compared with corresponding experimental data. The ex-tent of bottom emergence is investigated by varying parameters of the structure and incoming waves. The effect of shallow water depth is also examined.