● Bow flare slamming

　The water impact problem can be classified roughly into two kinds, the  Wagner-type and the Bagnold-type. As the bow flare slamming doesn't bring the air entrainment, it can be treated as the Wagner-typed impact. Although the body shape is assumed to be a flat plate, the water pile-up due to water entry is taken into account in the Wagner's theory. Moreover, it is very  useful for rough design, because the pressure distribution is given as a simple mathematical formula. Recently we can make use of the generalized theory, which is applicable to the body
　However, since these are based on the plate approximation of a body shape in principle, the estimation error becomes larger and larger and results in overestimation of the  pressure as the contact angle (viz. deadrise angle) gets large. Additionally, the relative motion with wave surface needs to be treated as to the ship motion in waves. The impact force is formulated as the momentum change of added mass in the Wagner's theory. So, for better estimation, it is important to determine whether water impact occurs during ship motions. We are challenging the development of the rational method by using the BEM.
　The simulation of water entry for the 2D body with a bow cross-section is shown, where the bulbous bow is supposed to emerge from the free surface. This is one of computational results for the water impact of the body with concave part.

Periodic motion with velocity 12.1 [m/s] and angular frequency 0.696 [rad/s].

The drop speed is the case of 4.0[m/s].