Vertical 2-D Wave Numerical Model Research On The Hydraulic Natures Of Breakwaters

The breakwater's hydraulic characteristic determines the design and the risk analysis of the breakwater as well as the development of the new breakwater styles, so it is an important topic on wave mechanics and the breakwater research. What's more, the wave pressure,reflection,transmission and some other exterior characteristics of breakwaters are all correlated closely with the internal characteristics, such as the flow-field structure, the speed distribution and its changing rule. This article conducts researches to the wave flow-field around the breakwater by using both physical model experiment such as the flow-field PIV experiment and the vertical two-dimensional numerical wave-model, which can reflect the motion of the uncompressible cohesive fluid, and studies on four kinds of breakwaters under different working conditions.There are some questions about the breakwater work mechanism which have caused wide attention but have not been completely solved, have been studied in this paper.This dissertation launches the discussion on the aspects of the existence and development of vortex around the breakwater, the reflection characteristic of the incomplete standing wave and the wave pressure variation in front of the vertical wall under the overtopping wave condition,the relations between vortex and hydraulic characteristic around the new quarter-circle breakwater,the position variation of antinodes and nodes in front of smooth slop,wave overtopping, reflection, the wave strength and the flow-field characteristic when of the chamfered vertical wall and the overhanging vertical wall.The research showes that there exists vortex around the submerged breakwater, the clockwise vortex and the anti-clockwise vortex develop in turn in a cycle, and as the wave's non-linear degree enhances, the voticity of vortex increases. Moreover, when the submerged depth is bigger, vortex behind the submerged breakwater approaches the dike wall and the base, which is a big threat to the breakwater's security. With the influence of the flow-field and under the same wave height condition, wave pressure of the submerged breakwater is smaller than complete set-up wave pressure, also, the wave profile becomes steep and the non-linear degree enhances. As compared with the semicircle breakwater, around the new quarter-circle breakwater exists obviously bigger clockwise vortex. So with the fierce dissipation of energy, the horizontal wave pressure in positive direction of the quarter-circle breakwater becomes bigger and in negative direction becomes smaller than the semicircle breakwater. When reflection on slop, along with the slop angle gradually reducing, for the calculation of the approaching to the shore translocation of the first node in front of the slope, the result based on numerical simulation is consistent with the theoretical calculation result. Besides, the theoretic obtained from physical model experiment has been validated by the numerical simulate result. When the top slopping angle changes, the chamfered vertical wall indicates superiority on the breakwater's stability, and the overhanging vertical wall shows obvious superiority on reducing overtopping wave, but when its top slopping angle becomes bigger, the amplitude of the horizontal and vertical wave pressure all becomes bigger, which is extremely disadvantageous to the breakwater's stability.