一种圆台型人工鱼礁非线性波浪作用受力分析

Non-Linear Analysis of the Horizontal Wave Force on A Type of Frustum Cones Artificial Reef

中文关键词: 人工鱼礁  Morison方程  二阶Stokes波  三维波浪数值水槽  波浪力  稳定性

英文关键词: Artificial reef  Morison equation  Second-order stokes wave  3D numerical wave tank  Wave force  Stability characteristics

中文摘要:

      为探求人工鱼礁水平波浪受力的非线性影响因素，获取更接近实际水平波浪力的数值计算方法，以校核验证鱼礁在海底的力学稳定性。本研究基于二阶Stokes波浪理论，借助无量纲化方法对计算水平波浪力的Morison方程进行非线性因素分析。以一种圆台型人工鱼礁为例，采用计算流体力学方法实施边界造波，建立求解鱼礁波浪力的三维非线性波浪数值水槽模型。依据数值计算结果，采用回归分析方法，求得鱼礁在二阶Stokes波浪作用下，正向最大受力(Fmax)与波陡(δ)最佳关系方程：Fmax=0.89+110.44δ，相关系数(R2)为0.9795；最大负向受力(F–max)与波陡(δ)最佳关系方程：Fmax=0.1083.52δ，相关系数(R2)为0.9899。圆台型鱼礁在本研究中给定最小与最大波陡波浪下的不漂移安全系数与不翻滚安全系数分别为3.45、2.11与7.54、3.96。研究表明，影响人工鱼礁波浪受力的主要非线性因子为波陡项，随着波陡的增加，非线性作用逐渐加强。鱼礁水平波浪力值随波浪运动做周期性正、负变化，同一时刻，其受力值随着波陡值的增加而增大；鱼礁正、负向最大波浪力与波浪波陡值分别呈正、负线性增长关系；圆台型式人工鱼礁抗滑移与抗翻滚特性较好，在大波陡波浪作用下具有良好的安全稳定性。

英文摘要:

      To acquire the actual wave force on an artificial reef under wave action and verify the stability of the artificial reef at the bottom of the sea, the influences of various nonlinear factors on the wave force acting on the artificial reef and numerical computation method for wave force should be analyzed and obtained. In this study, the nonlinear characteristic of the Morison equation for the horizontal wave force was analyzed using the dimensionless method based on the second-order Stokes wave theory. In addition, based on the computational fluid dynamics and finite volume method, adopting the Boundary wave method, a 3D numerical wave tank was established by the volume of fluid method. On account of the numerical results, the optimized relational expression of the maximum wave force and wave steepness was fitted by linear regression analysis method. The optimum equations of the maximum positive/negative horizontal force (Fmax/F–max) and wave steepness (δ) were Fmax = –0.89 + 110.44δ and F–max = –0.10–83.52δ, and the correlation coefficients were 0.9795 and 0.9899, respectively. The coefficient of anti-rolling and coefficient of anti-slide were 2.11 and 3.96, respectively, under the action of waves with the largest wave steepness. The results indicated that the main non-linear factor for the horizontal wave force acting on the artificial reef was wave steepness and the nonlinear effect enhances with increase in the number value. Taking a type of frustum cones artificial reef as an example, the maximum positive and negative horizontal wave force and the corresponding wave and pressure fields around the artificial reef were obtained. According to the numerical simulation results, the horizontal wave force of the artificial reef appeared to change periodically along with wave motion and increased with wave steepness. The results of stability calibration showed that the frustum cones artificial reef remained fairly stable on the sea floor at different test conditions, and it is well suited to the much larger wave heights in the sea.