In the two-dimensional model, total number of particles is increased as 768, 1488, 2208, 2928, and 3648. The model has 48 side particles fixedly and 16, 31, 46, 61, and 76 particles on the horizontal axis (see Fig. 4). Then, one interface particle is placed on each domain boundary. Hundred time steps are calculated with each step of 0.001 s. The smoothing length $h$ is 0.05 m and the initial mesh spacing sets the minimum to $3h$. Fluid density is 1000 kg/m^{3} and the speed of sound is 5 m/s.