In ocean engineering, the applications are usually related to a free surface which brings so many interesting physical phenomena （e.g. water waves, impacts, splashing jets, etc.）. To model these complex free surface...In ocean engineering, the applications are usually related to a free surface which brings so many interesting physical phenomena （e.g. water waves, impacts, splashing jets, etc.）. To model these complex free surface flows is a tough and challenging task for most computational fluid dynamics （CFD） solvers which work in the Eulerian framework. As a Lagrangian and meshless method, smoothed particle hydrodynamics （SPH） offers a convenient tracking for different complex boundaries and a straightforward satisfaction for different boundary conditions. Therefore SPH is robust in modeling complex hydrodynamic problems characterized by free surface boundaries, multiphase interfaces or material discontinuities. Along with the rapid development of the SPH theory, related numerical techniques and high-performance computing technologies, SPH has not only attracted much attention in the academic community, but also gradually gained wide applications in industrial circles. This paper is dedicated to a review of the recent developments of SPH method and its typical applications in fluid-structure interactions in ocean engineering. Different numerical techniques for improving numerical accuracy, satisfying different boundary conditions, improving computational efficie- ncy, suppressing pressure fluctuations and preventing the tensile instability, etc., are introduced. In the numerical results, various typical fluid-structure interaction problems or multiphase problems in ocean engineering are described, modeled and validated. The prospective developments of SPH in ocean engineering are also discussed.展开更多
As a popular meshfree particle method,the smoothed particle hydrodynamics(SPH) has suffered from not being able to di-rectly implement the solid boundary conditions.This influences the SPH approximation accuracy and h...As a popular meshfree particle method,the smoothed particle hydrodynamics(SPH) has suffered from not being able to di-rectly implement the solid boundary conditions.This influences the SPH approximation accuracy and hinders its further de-velopment and application to engineering and scientific problems.In this paper,a coupled dynamic solid boundary treatment(SBT) algorithm has been proposed,after investigating the features of existing SPH SBT algorithms.The novelty of the cou-pled dynamic SBT algorithm includes a new repulsive force between approaching fluid and solid particles,and a new numeri-cal approximation scheme for estimating field functions of virtual solid particles.The new SBT algorithm has been examined with three numerical examples including a typical dam-break flow,a dam-break flow with a sharp-edged obstacle,and a water entry problem.It is demonstrated that SPH with this coupled dynamic boundary algorithm can lead to accurate results with smooth pressure field,and that the new SBT algorithm is also suitable for complex and even moving solid boundaries.展开更多
为了充分发挥光滑粒子流体动力学方法(Smoothed Particle Hydrodynamics,SPH)易于处理大变形以及有限元(Finite Element Method,FEM)计算精度和效率高的优势,论文基于无网格粒子接触算法,在有限元节点处设置背景粒子,通过接触力的方式计...为了充分发挥光滑粒子流体动力学方法(Smoothed Particle Hydrodynamics,SPH)易于处理大变形以及有限元(Finite Element Method,FEM)计算精度和效率高的优势,论文基于无网格粒子接触算法,在有限元节点处设置背景粒子,通过接触力的方式计算SPH粒子和有限单元之间的接触问题.使用SPH-FEM接触算法分别对球头钢弹斜冲击钢板和平头钢弹正冲击钢板的情况进行了三维数值计算,SPH采用完全变光滑长度算法,FEM采用矩阵向量积的EBE(Element-By-Element)算法.将SPH-FEM接触算法的计算结果与LS-DYNA的计算结果以及实验结果进行了对比验证.展开更多
Pseudo-particle modeling (PPM) is a particle method (PM) proposed in 1996. Though it is effective for the simulation of microscopic particle-fluid systems, its application to practical systems is still limited by comp...Pseudo-particle modeling (PPM) is a particle method (PM) proposed in 1996. Though it is effective for the simulation of microscopic particle-fluid systems, its application to practical systems is still limited by computational cost. In this note, we speed up the computation by using a combination of weighted averaging with finite difference techniques to upgrade the particle interactions to a fluid element level, which conforms to the Navier-Stokes equation. The approach, abbreviated to MaPPM, is then applied to the problem of one-dimensional Poiseuille flow with a quantitative comparison to the results of another related PM--smoothed particle hydrodynamics (SPH), where the accuracy and efficiency of MaPPM is found to be much better than that of SPH. Flows around a cylinder and multiple freely moving particles are also simulated with the new model, resulting in reasonable flow pattern and drag coefficient. The convergence and robustness of the algorithm prove promising.展开更多
针对某典型前缘结构,研究了使用纤维金属层板(Fibre Metal Laminates,FMLs)蒙皮进行抗鸟撞设计的可行性。以显式动态冲击分析程序PAM-CRASH为平台,结合由鸟撞平板试验结果验证的鸟体本构模型参数,建立了鸟撞前缘结构数值模型。通过计算...针对某典型前缘结构,研究了使用纤维金属层板(Fibre Metal Laminates,FMLs)蒙皮进行抗鸟撞设计的可行性。以显式动态冲击分析程序PAM-CRASH为平台,结合由鸟撞平板试验结果验证的鸟体本构模型参数,建立了鸟撞前缘结构数值模型。通过计算研究了使用不同蒙皮(铝合金、FMLs)的前缘结构在鸟撞作用下的变形破坏模式及吸能效果。结果表明:采用适当铺层的FMLs蒙皮可以有效地提高前缘结构的抗鸟撞性能。研究结论对飞机结构的抗鸟撞研究具有一定的参考价值。展开更多
应用光滑粒子法(SPH)对具有间断面的不同介质的流动问题进行模拟分析.在现有的SPH方法的理论基础上进行修正,通过对密度近似方程进行正则化处理,在理想气体状态方程中引入Van Der Waals修正项以及对物质点运动速度进行修正,模拟了密度...应用光滑粒子法(SPH)对具有间断面的不同介质的流动问题进行模拟分析.在现有的SPH方法的理论基础上进行修正,通过对密度近似方程进行正则化处理,在理想气体状态方程中引入Van Der Waals修正项以及对物质点运动速度进行修正,模拟了密度相差较大的两相流动问题,并且使用图解分析了两相交界面在模拟过程中的清晰程度.通过气(液)泡上升以及两相溃坝问题对SPH方法在两相流动问题模拟中的可行性进行了分析.最后应用修正后的SPH方法有效再现了两相流动的物理过程,并且能清晰分辨不同介质之间的交界面,从而说明SPH方法能有效对两相流动进行模拟.展开更多
基金Project supported by the National Natural Science Foun-dation of China(Grant Nos.U1430236,51609049)the China Postdoctoral Science Foundation(Grant No.2015M581432)the China Scholarship Council(CSC,Grant No.201506680004)
文摘In ocean engineering, the applications are usually related to a free surface which brings so many interesting physical phenomena （e.g. water waves, impacts, splashing jets, etc.）. To model these complex free surface flows is a tough and challenging task for most computational fluid dynamics （CFD） solvers which work in the Eulerian framework. As a Lagrangian and meshless method, smoothed particle hydrodynamics （SPH） offers a convenient tracking for different complex boundaries and a straightforward satisfaction for different boundary conditions. Therefore SPH is robust in modeling complex hydrodynamic problems characterized by free surface boundaries, multiphase interfaces or material discontinuities. Along with the rapid development of the SPH theory, related numerical techniques and high-performance computing technologies, SPH has not only attracted much attention in the academic community, but also gradually gained wide applications in industrial circles. This paper is dedicated to a review of the recent developments of SPH method and its typical applications in fluid-structure interactions in ocean engineering. Different numerical techniques for improving numerical accuracy, satisfying different boundary conditions, improving computational efficie- ncy, suppressing pressure fluctuations and preventing the tensile instability, etc., are introduced. In the numerical results, various typical fluid-structure interaction problems or multiphase problems in ocean engineering are described, modeled and validated. The prospective developments of SPH in ocean engineering are also discussed.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10942004, 11172306)the National Defense Innovation Funds of the Chinese Academy of Sciences (Grant No. Y175031XML)
文摘As a popular meshfree particle method,the smoothed particle hydrodynamics(SPH) has suffered from not being able to di-rectly implement the solid boundary conditions.This influences the SPH approximation accuracy and hinders its further de-velopment and application to engineering and scientific problems.In this paper,a coupled dynamic solid boundary treatment(SBT) algorithm has been proposed,after investigating the features of existing SPH SBT algorithms.The novelty of the cou-pled dynamic SBT algorithm includes a new repulsive force between approaching fluid and solid particles,and a new numeri-cal approximation scheme for estimating field functions of virtual solid particles.The new SBT algorithm has been examined with three numerical examples including a typical dam-break flow,a dam-break flow with a sharp-edged obstacle,and a water entry problem.It is demonstrated that SPH with this coupled dynamic boundary algorithm can lead to accurate results with smooth pressure field,and that the new SBT algorithm is also suitable for complex and even moving solid boundaries.
文摘为了充分发挥光滑粒子流体动力学方法(Smoothed Particle Hydrodynamics,SPH)易于处理大变形以及有限元(Finite Element Method,FEM)计算精度和效率高的优势,论文基于无网格粒子接触算法,在有限元节点处设置背景粒子,通过接触力的方式计算SPH粒子和有限单元之间的接触问题.使用SPH-FEM接触算法分别对球头钢弹斜冲击钢板和平头钢弹正冲击钢板的情况进行了三维数值计算,SPH采用完全变光滑长度算法,FEM采用矩阵向量积的EBE(Element-By-Element)算法.将SPH-FEM接触算法的计算结果与LS-DYNA的计算结果以及实验结果进行了对比验证.
文摘滑坡的仿真模拟是分析滑坡运动过程并预测滑坡影响范围的重要手段之一。采用了基于岩土体弹塑性本构模型的光滑粒子流体动力学(smoothed particle hydrodynamics,SPH)方法,模拟滑坡失稳后岩土材料的特性。该模型以经典弹塑性理论为基础,包含了线弹性变形和德鲁克-普拉格(Drucker-Prager,DP)屈服准则下非关联流动法则的塑性变形,由于考虑了岩土材料的塑性特征,该方法能够更加精确和真实地模拟滑坡运动过程。同时,结合地理信息系统(geographic information system,GIS)的数据管理与建模,进一步将该SPH模型应用到滑坡模拟的实例中。基于GIS平台,完成了能够自动生成计算模拟所需的滑坡粒子数据的C#程序。该程序同时生成了高精度的滑坡体实粒子和复杂、不规则的边界虚粒子。实现了一系列模型建模与模拟计算,并验证了该方法的精度,还将此模型与方法应用在汶川地震中引发的大光包滑坡实例中,模拟结果与现场收集数据十分符合。
基金This work was supported by the National Key Program for Developing Basic Sciences (Grant No. Gl 999032801).
文摘Pseudo-particle modeling (PPM) is a particle method (PM) proposed in 1996. Though it is effective for the simulation of microscopic particle-fluid systems, its application to practical systems is still limited by computational cost. In this note, we speed up the computation by using a combination of weighted averaging with finite difference techniques to upgrade the particle interactions to a fluid element level, which conforms to the Navier-Stokes equation. The approach, abbreviated to MaPPM, is then applied to the problem of one-dimensional Poiseuille flow with a quantitative comparison to the results of another related PM--smoothed particle hydrodynamics (SPH), where the accuracy and efficiency of MaPPM is found to be much better than that of SPH. Flows around a cylinder and multiple freely moving particles are also simulated with the new model, resulting in reasonable flow pattern and drag coefficient. The convergence and robustness of the algorithm prove promising.
文摘针对某典型前缘结构,研究了使用纤维金属层板(Fibre Metal Laminates,FMLs)蒙皮进行抗鸟撞设计的可行性。以显式动态冲击分析程序PAM-CRASH为平台,结合由鸟撞平板试验结果验证的鸟体本构模型参数,建立了鸟撞前缘结构数值模型。通过计算研究了使用不同蒙皮(铝合金、FMLs)的前缘结构在鸟撞作用下的变形破坏模式及吸能效果。结果表明:采用适当铺层的FMLs蒙皮可以有效地提高前缘结构的抗鸟撞性能。研究结论对飞机结构的抗鸟撞研究具有一定的参考价值。
文摘应用光滑粒子法(SPH)对具有间断面的不同介质的流动问题进行模拟分析.在现有的SPH方法的理论基础上进行修正,通过对密度近似方程进行正则化处理,在理想气体状态方程中引入Van Der Waals修正项以及对物质点运动速度进行修正,模拟了密度相差较大的两相流动问题,并且使用图解分析了两相交界面在模拟过程中的清晰程度.通过气(液)泡上升以及两相溃坝问题对SPH方法在两相流动问题模拟中的可行性进行了分析.最后应用修正后的SPH方法有效再现了两相流动的物理过程,并且能清晰分辨不同介质之间的交界面,从而说明SPH方法能有效对两相流动进行模拟.
