利用计算流体力学软件 Fluent 开展了三维动波浪壁圆柱绕流的数值模拟，建立了三维运动波浪壁圆柱模型，通过 C语言自编程序实现波浪壁面的运动控制，并保证壁面变形时网格的高质量。在来流速度 u ＝0.125 m/ s、雷诺数 Re ＝12500的情...利用计算流体力学软件 Fluent 开展了三维动波浪壁圆柱绕流的数值模拟，建立了三维运动波浪壁圆柱模型，通过 C语言自编程序实现波浪壁面的运动控制，并保证壁面变形时网格的高质量。在来流速度 u ＝0.125 m/ s、雷诺数 Re ＝12500的情况下，开展了动波浪壁波动速度 w＝0、0.0625、0.125、0.1875 m/ s 四个工况的计算分析，并比较了不同波动速度对流场结构、升力、阻力特性的影响。结果表明：动波浪壁圆柱能有效抑制流动的分离，消除交替脱落的尾涡，从而消除周期振荡的升力；在消除卡门涡街的同时，圆柱后驻点处的涡量值随波动速度增加而增加，其原因在于波形移动加大了壁面流体的速度，从而减小了圆柱前后的压力差，减小了阻力；随着波动速度的增大，平均阻力系数呈明显下降趋势，当波动速度为来流速度的1.5倍时，平均阻力系数相对于光滑圆柱下降了53.76％。展开更多
A numerical model of wave force upon continuous cylinder structures with a large diameter using the boundary element method (BEM) is presented. A numerical model of reflecting wave upon continuous cylinders was establ...A numerical model of wave force upon continuous cylinder structures with a large diameter using the boundary element method (BEM) is presented. A numerical model of reflecting wave upon continuous cylinders was established on the basis of linear wave theory.The fundamental solution to the Helmholtz equation within an infinite strip area that explicitly satisfies two infinite parallel boundaries is used together with Radiation condition rather than the solution of an infinite area.According to the proposed theory and method,the computer programs have been composed in Visual C ++ Development Studio.Several examples show that the technique and its program are feasible and efficient.And the wave forces upon continuous cylinders can be decreased by as much as 14%～24% under a ratio of D/L= 0.09～0.19 compared with the square caissons.展开更多
The wave force exerted on vertical piles of offshore structures is the main criterion in designing them.In structures with more than one large pile,the influence of piles on each other is one of the most important iss...The wave force exerted on vertical piles of offshore structures is the main criterion in designing them.In structures with more than one large pile,the influence of piles on each other is one of the most important issues being concerned in past researches.An efficient method for determining the interaction of piles is introduced in present research.First the wave force is calculated by the exact method using the diffraction theory,then in the finite difference numerical method the force is calculated by adding the velocity potentials of each pile and integration of pressure on their surface.The results showed that the ratio of the wave force on each of the double piles to a single pile has a damped oscillation around unity in which the amplitude of oscillation decreases with the increase in the spacing parameter.Also different wave incident directions and diffraction parameters were used and the results showed that the numerical solution has acceptable accuracy when the diffraction parameter is larger than unity.展开更多
文摘利用计算流体力学软件 Fluent 开展了三维动波浪壁圆柱绕流的数值模拟，建立了三维运动波浪壁圆柱模型，通过 C语言自编程序实现波浪壁面的运动控制，并保证壁面变形时网格的高质量。在来流速度 u ＝0.125 m/ s、雷诺数 Re ＝12500的情况下，开展了动波浪壁波动速度 w＝0、0.0625、0.125、0.1875 m/ s 四个工况的计算分析，并比较了不同波动速度对流场结构、升力、阻力特性的影响。结果表明：动波浪壁圆柱能有效抑制流动的分离，消除交替脱落的尾涡，从而消除周期振荡的升力；在消除卡门涡街的同时，圆柱后驻点处的涡量值随波动速度增加而增加，其原因在于波形移动加大了壁面流体的速度，从而减小了圆柱前后的压力差，减小了阻力；随着波动速度的增大，平均阻力系数呈明显下降趋势，当波动速度为来流速度的1.5倍时，平均阻力系数相对于光滑圆柱下降了53.76％。
基金Supported by National Natural Science Foundation of China(No.5990 90 0 5) National High Performance Computing Foundation of
文摘A numerical model of wave force upon continuous cylinder structures with a large diameter using the boundary element method (BEM) is presented. A numerical model of reflecting wave upon continuous cylinders was established on the basis of linear wave theory.The fundamental solution to the Helmholtz equation within an infinite strip area that explicitly satisfies two infinite parallel boundaries is used together with Radiation condition rather than the solution of an infinite area.According to the proposed theory and method,the computer programs have been composed in Visual C ++ Development Studio.Several examples show that the technique and its program are feasible and efficient.And the wave forces upon continuous cylinders can be decreased by as much as 14%～24% under a ratio of D/L= 0.09～0.19 compared with the square caissons.
文摘The wave force exerted on vertical piles of offshore structures is the main criterion in designing them.In structures with more than one large pile,the influence of piles on each other is one of the most important issues being concerned in past researches.An efficient method for determining the interaction of piles is introduced in present research.First the wave force is calculated by the exact method using the diffraction theory,then in the finite difference numerical method the force is calculated by adding the velocity potentials of each pile and integration of pressure on their surface.The results showed that the ratio of the wave force on each of the double piles to a single pile has a damped oscillation around unity in which the amplitude of oscillation decreases with the increase in the spacing parameter.Also different wave incident directions and diffraction parameters were used and the results showed that the numerical solution has acceptable accuracy when the diffraction parameter is larger than unity.
