波浪与新型双排开孔圆筒防波堤相互作用三维数值模拟

双排开孔圆筒防波堤是基于圆筒、板式结构的一种复合式新型结构型式;基于不可压缩两相流模型建立三维数值波浪水槽,通过RNG k-ε湍流模型进行湍流封闭,并采用TruVOF方法捕捉自由液面,开展波浪与双排开孔圆筒防波堤相互作用数值模拟,探究相对排间距、开孔率对新型双排开孔圆筒防波堤消浪性能的影响,分析了后排开孔圆筒防波堤附近的复杂水动力现象和流动特性.结果表明,在本文研究工况范围内,沿程平均波高随相对排间距的增大先增大后减小,随开孔率的增大而增大,周期对沿程平均波高的影响没有明显规律;当B/D=9, e=23.11%时,新型双排开孔圆筒防波堤消浪效果最优,反射系数在0.4～0.46之间,透射系数在0.3～0.35之间,耗散系数在0.8～0.85之间;自由液面破碎、水气掺混、环状涡运动演化是新型双排开孔圆筒防波堤紊动耗能消波的主要原因;相对排间距会引起后排防波堤附近涡量分布以及剪切层形态的变化,从而导致不同的紊动特性,影响双排开孔圆筒防波堤消浪特性.研究结果可以为新型双排开孔圆筒防波堤工程设计与消浪机理研究提供理论支撑.

THREE DIMENSIONAL NUMERICAL SIMULATION OF WAVE INTERACTION WITH A NEW TYPE OF DOUBLE ROW PERFORATED CYLINDER BREAKWATER

The double row perforated cylinder breakwater is a new composite structure based on the cylinder and plate breakwater. The three-dimensional numerical wave flume is established based on the incompressible two-phase flow model. The turbulent closure is carried out by RNG k-ε turbulence model, and the TruVOF method is used to capture the free liquid surface. The influence of relative row spacing and opening rate on the wave dissipation performance of double row perforated cylinder breakwater is explored, and the special hydrodynamic phenomena and flow characteristics near the back row perforated cylinder breakwater are analyzed. The results show that in the range of working conditions studied in this paper, the along-range average wave height increases and then decreases with the increase of relative row spacing, and increases with the increase of opening rate, and the effect of period on the along-range average wave height has no obvious rule; when B/D = 9, e = 23.11%, the double row perforated cylinder breakwater has the best wave dissipation effect, the reflection coefficient ranges from 0.4 to 0.46,the transmission coefficient is between 0.3 ~ 0.35, the dissipation coefficient is between 0.8 ~ 0.85. Free surface fragmentation, water-air mixing and annular eddy motion evolution are the main causes of wave dissipation and energy dissipation of double-row cylinder breakwater. The jet stage occurred more violent free liquid surface fragmentation and water-gas mixing, resulting in the increase of turbulent kinetic energy after the dike, the peak turbulent kinetic energy after the increase is about 2.5 times of that before the jet, and the violent turbulent energy dissipation occurred. The relative row spacing will cause the changes of vorticity distribution and shear layer morphology near the rear breakwater, which will lead to different turbulent characteristics and affect the wave breaking characteristics of the double row perforated cylinder breakwater. The research results can provide theoretical support for the engineering design of a new type of double-arranged cylindrical breakwater and the study of wave dissipation mechanism.