斜坡堤护面块体稳定性的数值模拟
摘要
斜坡式防波堤以其施工简单,可就地取材,易修复,消波性能好等优点,是港口和海岸工程中最常用的防护结构。在极端海况下,斜坡堤表面的人工护面块护面层会发生失稳或者断裂等破坏。目前国内外关于斜坡式护面块体稳定性的研究工作多是基于物理模型实验以及由此得出的经验公式。但是由于物模实验中比尺效应的影响,使得物模实验结果不能真实的反映出原型护面块体结构的强度。因此开展波浪作用下斜坡式防波堤稳定性的数值模拟方法研究具有十分重要的学术意义和工程应用价值。
本文建立了基于光滑粒子流体动力学方法(SPH)和离散元方法(DEM)的二维流固耦合数学模型。结构物的水动力条件采用通过黎曼解和CSPM修正后的SPH方法来模拟,造波边界和水槽固壁以及结构物动边界采用虚粒子法处理。离散护面块体的受力和运动采用本文建立离散元模型模拟。提出了流固交界面处的界面力平衡边界条件。应用波浪水槽内的物理模型实验验证了所建立的二维数学模型。通过数值计算模拟了波浪与斜坡堤离散护面块体的相互作用,分析了波浪沿斜坡堤爬坡越浪过程的流场变化特征以及波压力沿斜坡堤护面块体表面的分布规律,并用物理模型实验对胸墙上所受的破碎波压力数模结果进行了验证。
本文在所建立的二维SPH-DEM基础上进一步建立了三维SPH-DEM流固耦合数学模型。采用计算机可视化绘图技术和非结构化网格技术完成了三维数值防波堤的建立,提出了复杂形状离散护面块体间空隙内的SPH粒子的生成方法。基于OpenMP技术发展了适用于无网格粒子法(SPH和DEM)的并行算法,充分利用多核共享内存系统的计算资源,在采用链表搜索技术寻找最近相邻粒子的基础上,采用计算域分割并行算法来进行邻近粒子的并行搜索。应用所建立的三维数学模型模拟了规则波作用下离散护面块体上所受的波浪力和相邻块体间的接触力以及块体的运动过程。研究成果将为斜坡式防波堤离散护面块体的设计和优化提供一个新的技术手段。
The rubble mound breakwater is most widely used breakwaters, because it is easy to build, maintain and it has a good energy dissipation ability. Usually, these blocks, which may weight tens tons, can both remain structurally stable under the strong wave condition and dissipate wave energy. But when under extreme wave condition, these amour blocks may failure. The main failure mode is hydraulic instability and the breakage of amour blocks. Till now, the flow field and the energy dissipation within the amour layer of breakwaters are still poorly understood by researchers. The major method to study stability of breakwater is physic experiment. Unfortunately, due to the scale-effect, the hydraulic forces and the stress within the blocks can not be model correctly. So build a numerical model to study the stability of breakwaters becomes a focus reaching points.
In this paper, a fluid solid interaction numerical model, based on smooth particle hydrodynamic(SPH) and discrete element method(DEM), is developed. The fluid field is simulated by improved SPH, which governing equation was corrected by CSPM and Riemann-solver. The solid boundaries, such as wave maker, tank bottom and tank right wall are simulated by wall particles. The motion and the interaction between blocks are modeled using Multi-Sphere DEM method. The accuracy of proposed two dimension SPH-DEM model was verified by experimental results. The interaction between wave and amour blocks was simulated using proposed model. The variation of fluid field during the process of wave shoaling and the pressure distribution along the slope are analyzed. The impact pressures when the wave slams on the parapet are also compared with the experimental results.
Then, the two dimension SPH-DEM fluid solid interaction model was developed into three-dimension. A three dimension model building method, which based on the Computer Graphics Technology and unstructured mesh technology, is introduced to build three dimension numerical rubble mound breakwater. A three dimension complex region fluid particle fill algorithm is proposed. A parallel computing method based on OpenMP technology which can be used on multi-core shared memory computer is developed. Finally, a three dimension wave and amour blocks interaction example was simulated and the interaction force between wave, amour blocks and between blocks was analyzed. The research achievement of this paper proposed a new technology to design and optimize amour blocks.
本文建立了基于光滑粒子流体动力学方法(SPH)和离散元方法(DEM)的二维流固耦合数学模型。结构物的水动力条件采用通过黎曼解和CSPM修正后的SPH方法来模拟,造波边界和水槽固壁以及结构物动边界采用虚粒子法处理。离散护面块体的受力和运动采用本文建立离散元模型模拟。提出了流固交界面处的界面力平衡边界条件。应用波浪水槽内的物理模型实验验证了所建立的二维数学模型。通过数值计算模拟了波浪与斜坡堤离散护面块体的相互作用,分析了波浪沿斜坡堤爬坡越浪过程的流场变化特征以及波压力沿斜坡堤护面块体表面的分布规律,并用物理模型实验对胸墙上所受的破碎波压力数模结果进行了验证。
本文在所建立的二维SPH-DEM基础上进一步建立了三维SPH-DEM流固耦合数学模型。采用计算机可视化绘图技术和非结构化网格技术完成了三维数值防波堤的建立,提出了复杂形状离散护面块体间空隙内的SPH粒子的生成方法。基于OpenMP技术发展了适用于无网格粒子法(SPH和DEM)的并行算法,充分利用多核共享内存系统的计算资源,在采用链表搜索技术寻找最近相邻粒子的基础上,采用计算域分割并行算法来进行邻近粒子的并行搜索。应用所建立的三维数学模型模拟了规则波作用下离散护面块体上所受的波浪力和相邻块体间的接触力以及块体的运动过程。研究成果将为斜坡式防波堤离散护面块体的设计和优化提供一个新的技术手段。
The rubble mound breakwater is most widely used breakwaters, because it is easy to build, maintain and it has a good energy dissipation ability. Usually, these blocks, which may weight tens tons, can both remain structurally stable under the strong wave condition and dissipate wave energy. But when under extreme wave condition, these amour blocks may failure. The main failure mode is hydraulic instability and the breakage of amour blocks. Till now, the flow field and the energy dissipation within the amour layer of breakwaters are still poorly understood by researchers. The major method to study stability of breakwater is physic experiment. Unfortunately, due to the scale-effect, the hydraulic forces and the stress within the blocks can not be model correctly. So build a numerical model to study the stability of breakwaters becomes a focus reaching points.
In this paper, a fluid solid interaction numerical model, based on smooth particle hydrodynamic(SPH) and discrete element method(DEM), is developed. The fluid field is simulated by improved SPH, which governing equation was corrected by CSPM and Riemann-solver. The solid boundaries, such as wave maker, tank bottom and tank right wall are simulated by wall particles. The motion and the interaction between blocks are modeled using Multi-Sphere DEM method. The accuracy of proposed two dimension SPH-DEM model was verified by experimental results. The interaction between wave and amour blocks was simulated using proposed model. The variation of fluid field during the process of wave shoaling and the pressure distribution along the slope are analyzed. The impact pressures when the wave slams on the parapet are also compared with the experimental results.
Then, the two dimension SPH-DEM fluid solid interaction model was developed into three-dimension. A three dimension model building method, which based on the Computer Graphics Technology and unstructured mesh technology, is introduced to build three dimension numerical rubble mound breakwater. A three dimension complex region fluid particle fill algorithm is proposed. A parallel computing method based on OpenMP technology which can be used on multi-core shared memory computer is developed. Finally, a three dimension wave and amour blocks interaction example was simulated and the interaction force between wave, amour blocks and between blocks was analyzed. The research achievement of this paper proposed a new technology to design and optimize amour blocks.
引文
[1]Liu P L-F, Lin P, Chang K-A, Sakakiyama T. Numericalmodeling of wave interaction with porous structures. [J]. Waterw Port Coast and Ocean Eng, ASCE, 1999,125 (6):322-330.
[2]Hsu T-J, Sakakiyama T, Liu P L-F. A numerical model for wave motions and turbulence flows in front of a composite breakwater [J]. Coastal Engineering, 2002,46:25-50.
[3]Lara J L, Garcia N, Losada I J. RANS modelling applied to random wave interaction with submerged permeable structures. Coastal Engineering[J], 2006,53:395-417.
[4]Lara J L, Losada I J, Guanche R. Wave interaction with low-mound breakwaters using a RANS model. Ocean Engineering[J],2008,35:1388-1400.
[5]Losada I J, Lara J L, Damgaard E, Garcia N. Modelling of velocity and turbulence fields around and within low-crested rubble-mound breakwaters [J]. Coastal Engineering,2005,52:887-913.
[6]Karim M F, Tanimoto K, Hieu P D. Simulation of wave transformation in vertical permeable structure [J]. Offshore Polar Eng,2004,14:89-97.
[7]Karim M F, Tanimoto K, Hieu P D. Modelling and simulation of wave transformation in porous structures using VOF based two-phase flow model [J]. Applied Mathematical Modelling,2009,33:343-360.
[8]Cundall P A, Strack 0 D L. A discrete numerical model for granular assemblies[J]. Geotechnique,1979,29(1):47-65.
[9]李增志,2003.抛石防波堤稳定性的离散单元法分析：(硕士学位论文).天津：天津大学.
[10]Gotoh, H., Ikari, H., Yasuoka, T.,2009. Simulation of armor blocks in front of caisson breakwater by DEM-MPS hybrid model. Proceedings of the Nineteenth (2009) International Offshore and Polar Engineering Conference Osaka, Japan, 365-370.
[II]Munjiza, A., Owen, D. R. J., Bicanic, N.,1995. Combined finite-discrete element method in transient dynamics of fracturing solids. Engineering Computations,12 (2):145-174.
[12]Munjiza, A.,2004. The combined finite-discrete element method. Wiley:New York.
[13]Latham, J. P., Munjiza, A., Mindel, J., Xiang, J. S., Guises, R., Garcia, X., Pain, C., Gorman, G.., Piggott, M.,2008. Modeling of massive particulates for breakwater engineering using coupled FEMDEM and CFD. China Particuology,6(6):572-583.
[14]Potapov, A. V., Hunt M. L., Campbell, C.S.,2001. Liquid-solid flows using smoothed particle hydrodynamics and the discrete element method. Powder Technology,116:204-213.
[15]Cundall P A. A computer model for simulating progressive large scale movements in blocky rock systems[C]. Proceedings of the International Symposium Rock Fracture,1971:1-8.
[16]Mishra B K. A review of computer simulation of tumbling mill by the discrete element method:part Ⅰ-contact mechanics[C]. Int. J. Miner. Process, 2003,71:73-93
[17]刑纪波,俞良群,张瑞丰等.离散单元法的计算参数和求解方法选择.计算力学学报,1999,16(1)：47-51
[18]许志宝.基于离散单元法的大豆碰撞过程仿真分析[D].长春：吉林大学,2003.
[19]Cundall P. A. Formulation of a three-dimensional distinct element model-Part I. A scheme to detect and represent contacts in a system composed of many polyhedral blocks. Int. J. Rock Mech. Min. Sci.& Geomech. Abstr.1988, 25(3):117-125.
[20]王建全.三维块体系统接触检索算法与非连续并行分析[D].大连：大连理工大学,2006.
[21]Favier J F. Abbaspour-Fard M H; Kremmer M; Raji A 0. Shape representation of axi-symmetrical, non-spherical particles in discrete element simulation using multi-element particles [J]. Engineering Computations,1999,16(4):467-480
[22]Abbaspour-Fard M H. Theoretical Validation of a Multi-sphere, Discrete Element Model Suitable for Biomaterials Handling Simulation[J]. Biosystems Engineering,2004,88(2):153-161.
[23]Markauskas D, Kacianauskas R, Dziugys A, Navakas R. Investigation of adequacy of multi-sphere approximation of elliptical particles for DEM simulations [J]. Granular Matter,2010,12:107-123
[24]Garcia Z, Latham J P, Xiang J, Harrison J P. A clustered overlapping sphere algorithm to represent real particles in discrete element modelling[J]. Geotechnique,2009,59(9):779-784.
[25]任冰,高睿,金钊,王国玉,王永学.波浪对透空式结构物冲击作用的光滑粒子流体动力学数值模拟[J].海洋学报,2012,34(1)：164-177.
[26]Colagrossi A, Landrini M. Numerical simulation of interfacial flows by smoothed particle hydrodynamics[J].Journal of Computational Physics. 2003,191:448-475.
[27]Monaghan J J. Smoothed Particle Hydrodynamics[J]. Annual Review of Astronomical and Astrophysics,1992,30:543-574.
[28]Randles P W, Libersky L. Normalized SPH with stress points[J]. Int. J. Numer. Methods Eng.2000,48(10):1445-1462.
[29]Parshikov A N, Medin S A, Loukasenko I I. Improvements in SPH Method by means of interparticle contact algorithm and analysis of perforation tests at moderate projectile velocities[J]. Int. J. Impact Eng.2000,24(8):779-796.
[30]Zhao R, Faltinsen 0, Aarsnes J. Water entry of arbitrary two-dimensional sections with and without flow separation[C]. Proc.of 21st Symposium on Naval Hydrodynamics,1997,408-423.
[31]王本龙,Causon D C,刘桦.不可压缩SPH数学模型的并行求解[C].第二十一届全国水动力学研讨会暨第八届全国水动力学学术会议暨两岸船舶与海洋工程水动力学研讨会,2008,362-365.
[32]龚凯.基于光滑质点水动力学(SPH)方法的自由表面流动数值模拟研究[D].上海：上海交通大学,2009.
[2]Hsu T-J, Sakakiyama T, Liu P L-F. A numerical model for wave motions and turbulence flows in front of a composite breakwater [J]. Coastal Engineering, 2002,46:25-50.
[3]Lara J L, Garcia N, Losada I J. RANS modelling applied to random wave interaction with submerged permeable structures. Coastal Engineering[J], 2006,53:395-417.
[4]Lara J L, Losada I J, Guanche R. Wave interaction with low-mound breakwaters using a RANS model. Ocean Engineering[J],2008,35:1388-1400.
[5]Losada I J, Lara J L, Damgaard E, Garcia N. Modelling of velocity and turbulence fields around and within low-crested rubble-mound breakwaters [J]. Coastal Engineering,2005,52:887-913.
[6]Karim M F, Tanimoto K, Hieu P D. Simulation of wave transformation in vertical permeable structure [J]. Offshore Polar Eng,2004,14:89-97.
[7]Karim M F, Tanimoto K, Hieu P D. Modelling and simulation of wave transformation in porous structures using VOF based two-phase flow model [J]. Applied Mathematical Modelling,2009,33:343-360.
[8]Cundall P A, Strack 0 D L. A discrete numerical model for granular assemblies[J]. Geotechnique,1979,29(1):47-65.
[9]李增志,2003.抛石防波堤稳定性的离散单元法分析：(硕士学位论文).天津：天津大学.
[10]Gotoh, H., Ikari, H., Yasuoka, T.,2009. Simulation of armor blocks in front of caisson breakwater by DEM-MPS hybrid model. Proceedings of the Nineteenth (2009) International Offshore and Polar Engineering Conference Osaka, Japan, 365-370.
[II]Munjiza, A., Owen, D. R. J., Bicanic, N.,1995. Combined finite-discrete element method in transient dynamics of fracturing solids. Engineering Computations,12 (2):145-174.
[12]Munjiza, A.,2004. The combined finite-discrete element method. Wiley:New York.
[13]Latham, J. P., Munjiza, A., Mindel, J., Xiang, J. S., Guises, R., Garcia, X., Pain, C., Gorman, G.., Piggott, M.,2008. Modeling of massive particulates for breakwater engineering using coupled FEMDEM and CFD. China Particuology,6(6):572-583.
[14]Potapov, A. V., Hunt M. L., Campbell, C.S.,2001. Liquid-solid flows using smoothed particle hydrodynamics and the discrete element method. Powder Technology,116:204-213.
[15]Cundall P A. A computer model for simulating progressive large scale movements in blocky rock systems[C]. Proceedings of the International Symposium Rock Fracture,1971:1-8.
[16]Mishra B K. A review of computer simulation of tumbling mill by the discrete element method:part Ⅰ-contact mechanics[C]. Int. J. Miner. Process, 2003,71:73-93
[17]刑纪波,俞良群,张瑞丰等.离散单元法的计算参数和求解方法选择.计算力学学报,1999,16(1)：47-51
[18]许志宝.基于离散单元法的大豆碰撞过程仿真分析[D].长春：吉林大学,2003.
[19]Cundall P. A. Formulation of a three-dimensional distinct element model-Part I. A scheme to detect and represent contacts in a system composed of many polyhedral blocks. Int. J. Rock Mech. Min. Sci.& Geomech. Abstr.1988, 25(3):117-125.
[20]王建全.三维块体系统接触检索算法与非连续并行分析[D].大连：大连理工大学,2006.
[21]Favier J F. Abbaspour-Fard M H; Kremmer M; Raji A 0. Shape representation of axi-symmetrical, non-spherical particles in discrete element simulation using multi-element particles [J]. Engineering Computations,1999,16(4):467-480
[22]Abbaspour-Fard M H. Theoretical Validation of a Multi-sphere, Discrete Element Model Suitable for Biomaterials Handling Simulation[J]. Biosystems Engineering,2004,88(2):153-161.
[23]Markauskas D, Kacianauskas R, Dziugys A, Navakas R. Investigation of adequacy of multi-sphere approximation of elliptical particles for DEM simulations [J]. Granular Matter,2010,12:107-123
[24]Garcia Z, Latham J P, Xiang J, Harrison J P. A clustered overlapping sphere algorithm to represent real particles in discrete element modelling[J]. Geotechnique,2009,59(9):779-784.
[25]任冰,高睿,金钊,王国玉,王永学.波浪对透空式结构物冲击作用的光滑粒子流体动力学数值模拟[J].海洋学报,2012,34(1)：164-177.
[26]Colagrossi A, Landrini M. Numerical simulation of interfacial flows by smoothed particle hydrodynamics[J].Journal of Computational Physics. 2003,191:448-475.
[27]Monaghan J J. Smoothed Particle Hydrodynamics[J]. Annual Review of Astronomical and Astrophysics,1992,30:543-574.
[28]Randles P W, Libersky L. Normalized SPH with stress points[J]. Int. J. Numer. Methods Eng.2000,48(10):1445-1462.
[29]Parshikov A N, Medin S A, Loukasenko I I. Improvements in SPH Method by means of interparticle contact algorithm and analysis of perforation tests at moderate projectile velocities[J]. Int. J. Impact Eng.2000,24(8):779-796.
[30]Zhao R, Faltinsen 0, Aarsnes J. Water entry of arbitrary two-dimensional sections with and without flow separation[C]. Proc.of 21st Symposium on Naval Hydrodynamics,1997,408-423.
[31]王本龙,Causon D C,刘桦.不可压缩SPH数学模型的并行求解[C].第二十一届全国水动力学研讨会暨第八届全国水动力学学术会议暨两岸船舶与海洋工程水动力学研讨会,2008,362-365.
[32]龚凯.基于光滑质点水动力学(SPH)方法的自由表面流动数值模拟研究[D].上海：上海交通大学,2009.