ward is the error in the estimation of wave breaking effects.
Figure 4 Water surface elevation around submerged breakwater estimated in Boussinesq equation (The incident wave height is 2.5cm)
Figure 5 Wave profile on and at backward of submerged breakwater (The incident wave height is 2.5cm)
4. CHARACTERISTIC OF CURRENT
(1) Current Occurred by Regular Waves
Figure 6 shows the profile of the water surface elevation and current velocity around the submerged breakwater. The amplitudes of the un-steady current component is much larger than those of the steady component at the forward of the submerged breakwater (U1) and at the current velocity measured at U1 is 7.2cm/s, while the amplitude calculated in small amplitude wave theory is 4.5cm/s. The amplitude can be approximately estimated in the theory. The steady current velocity at the point U1 is 2.2cm/s.
But the steady current component is much larger than the un-steady component at the backward of the submerged breakwater (U2 and U3). The steady current velocities measured at U2 and U3 are 7.0 and 8.8m/s, while the amplitudes of the un-steady current velocities are 2.8 and 2.3cm/s. The strong steady current may have the influence on the serious erosion.
Figure 7 shows the variations of the current velocities measured at the points from U4 to U6. In this figure, the current component (a) is due to the overtopped incident waves from the forward of the submerged breakwater, the component (b) the waves diffracted by the bothheads of the breakwater. This figure demonstrates that the overtopped incident waves and diffracted waves are composed on the breakwater crown.
Figure 6 Profile of current velocity around submerged breakwater
