The water impact of one and twin free-falling wedges is numerically investigated by a Cartesian grid multiphase flow model. The effects of the drop velocity and the gap distance on the hydrodynamic behaviors are parametrically investigated. The numerical model involves a radial basis function ghost cell method (RBFGCM) for treating moving bodies and a gradient-augmented level set method (GALS) method for capturing violent free surfaces. A case of twin wedges entering water is simulated to validate the accuracy of the present method. Good convergences are achieved. Then, the water entry of one and twin wedges in free falling is considered. The interaction mechanisms between twin wedges are discussed by comprehensively examining the variation patterns of the slamming load, the moment, the local pressure, and the fluid field. It is found that the second slamming load and the huge pressure pulse occur at the transition stage at narrow gap distances. The hydrodynamic interaction has more significant effects on the local pressure than that on the global load. In addition, distinct hydrodynamic phenomena for twin wedges entering water are observed such as the connection of the pressure contours, the extremely large jet flow, formation of the cavity, and even the ventilation.

Wave forces can form a serious threat to offshore platforms and ships. The damage produced by these forces of nature jeopardizes their operability as well as the well-being of their crews. Similar remarks apply to coastal defense systems. To develop the knowledge needed to safely design these constructions, in close cooperation with MARIN and the offshore industry the numerical simulation method ComFLOW is being developed. So far, its development was focussed on predicting wave loads (green water, slamming) on fixed structures, and for those applications the method is already being used successfully by the offshore industry. Often, the investigated object (ship, floating platform) is dynamically moving under the influence of these wave forces, and its hydrodynamic loading depends upon the position of the object with respect to the oncoming waves. Predicting the position (and deformation) of the body is an integral part of the (scientific and engineering) problem. The paper will give an overview of the algorithmic developments necessary to describe the above-mentioned physical phenomena. In particular attention will be paid to fluid-solid body and fluid-structure interaction and non-reflecting outflow boundary conditions. Several illustrations including validation, will demonstrate the prediction capabilities of the simulation method.