基于光滑粒子流体动力学方法的溃坝水流模拟
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摘要
受全球气候变暖的影响,由极端天气引发的类似溃坝等问题发生的概率大大增加,深入研究溃坝水流的水动力特性势在必行。在分析光滑粒子流体动力学基本原理的基础上,提出了一种改进的边界处理方法,即将接近壁面的流体视为层流,在耦合动力边界附近引入层流黏性近似边界层理论。采用该方法对溃坝水流进行数值模拟,将SPH数值模拟得到的外轮廓、自由液面高度以及压力与实验结果进行了比较和分析。结果表明:改进的边界处理方法较完整地得到了水流与壁面相互作用而产生的多种复杂的物理现象,其外部轮廓与实验非常吻合;自由表面融合过程中液面间冲击的能量耗散会导致融合后的液面高度存在一些差异;不同监测点处压力随时间的变化基本落在置信区间之内。数值模拟结果与实验结果吻合度较高,验证了改进方案的可靠性和计算结果的准确性。
Under the influence of global warming, the probability of natural disasters such as dam-break problems caused by extreme weather greatly increase, so it is imperative to study the hydrodynamic characteristics of dam-break flow. Based on the study of the basic principles of smooth particle hydrodynamics, an improved boundary processing method was proposed. In this method, the fluid close to the wall was regarded as laminar flow, and the laminar viscosity approximate boundary layer theory was applied near the coupled dynamic boundary. This method was used to simulate the dam-break flow, then the outer contour, free surface level and the change of pressure with time obtained by SPH numerical simulation were compared with the experimental results. The results showed that the improved boundary treatment method has obtained a variety of complex physical phenomena caused by the interaction between water flow and wall surface, the outer contour was in good agreement with the experiment. Due to the energy dissipation problem of liquid surface impact during free surface fusion, there was some difference in the height of the liquid level after the fusion; the change of pressure with time at different monitoring points basically fell within the confidence interval. The numerical simulation results were in good agreement with the experimental results, which verified the reliability of the improved scheme and the accuracy of the calculated results.
Under the influence of global warming, the probability of natural disasters such as dam-break problems caused by extreme weather greatly increase, so it is imperative to study the hydrodynamic characteristics of dam-break flow. Based on the study of the basic principles of smooth particle hydrodynamics, an improved boundary processing method was proposed. In this method, the fluid close to the wall was regarded as laminar flow, and the laminar viscosity approximate boundary layer theory was applied near the coupled dynamic boundary. This method was used to simulate the dam-break flow, then the outer contour, free surface level and the change of pressure with time obtained by SPH numerical simulation were compared with the experimental results. The results showed that the improved boundary treatment method has obtained a variety of complex physical phenomena caused by the interaction between water flow and wall surface, the outer contour was in good agreement with the experiment. Due to the energy dissipation problem of liquid surface impact during free surface fusion, there was some difference in the height of the liquid level after the fusion; the change of pressure with time at different monitoring points basically fell within the confidence interval. The numerical simulation results were in good agreement with the experimental results, which verified the reliability of the improved scheme and the accuracy of the calculated results.
引文
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[2] Lobovsky L,Botia-Vera E,Castellana F,et al.Experimental investigation of dynamic pressure loads during dam break[J].Journal of Fluids and Structures,2014(48):407-434.
[3] Lee T,Zhou Z,Cao Y.Numerical simulations of hydraulic jumps in water sloshing and water impacting[J].Journal of Fluids Engineering,2002,124(1):215-226.
[4] Buchner B.Green water on ship-type offshore structures[D].Delft:Delft University of Technology,2002.
[5] Cercos-Pita J L.AQUAgpusph,a new free 3D SPH solver accelerated with OpenCL[J].Computer Physics Communications,2015(192):295-312.
[6] Nguyen V T,Park W G.A free surface flow solver for complex three‐dimensional water impact problems based on the VOF method[J].International Journal for Numerical Methods in Fluids,2016,82(1):3-34.
[7] Mokrani C,Abadie S.Conditions for peak pressure stability in VOF simulations of dam break flow impact[J].Journal of Fluids and Structures,2016(62):86-103.
[8] Sun P,Ming F,Zhang A.Numerical simulation of interactions between free surface and rigid body using a robust SPH method[J].Ocean Engineering,2015(98):32-49.
[9] Aureli F,Dazzi S,Maranzoni A,et al.Experimental and numerical evaluation of the force due to the impact of a dam-break wave on a structure[J].Advances in Water Resources,2015(76):29-42.
[10] Sun P,Ming F,Zhang A.Numerical simulation of interactions between free surface and rigid body using a robust SPH method[J].Ocean Engineering,2015(98):32-49.
[11] Oger G,Marrone S,Le Touzé D,et al.SPH accuracy improvement through the combination of a quasi-Lagrangian shifting transport velocity and consistent ALE formalisms[J].Journal of Computational Physics,2016(313):76-98.
[12] 彭荣强.应用等位函数法模拟溃坝流动[J].长江科学院院报,2008,25(2):11-12.
[13] Violeau D,Rogers B D.Smoothed particle hydrodynamics (SPH) for free-surface flows:past,present and future[J].Journal of Hydraulic Research,2016,54(1):1-26.
[14] Shadloo M S,Oger G,Le Touzé D.Smoothed particle hydrodynamics method for fluid flows,towards industrial applications:Motivations,current state,and challenges[J].Computers & Fluids,2016(136):11-34.
[15] Liu G R,Liu M B.Smoothed particle hydrodynamics:a meshfree particle method[M].Newyork:World Scientific,2003.
[16] Liu M B,Liu G R.Smoothed particle hydrodynamics (SPH):an overview and recent developments[J].Archives of Computational Methods in Engineering,2010,17(1):25-76.
[17] Yue W,Lin C L,Patel V C.Numerical simulation of unsteady multidimensional free surface motions by level set method[J].International Journal for Numerical Methods in Fluids,2003,42(8):853-884.
[18] Lv X,Zou Q,Zhao Y,et al.A novel coupled level set and volume of fluid method for sharp interface capturing on 3D tetrahedral grids[J].Journal of Computational Physics,2010,229(7):2573-2604.
[19] Gingold R A,Monaghan J J.Smoothed particle hydrodynamics:theory and application to non-spherical stars[J].Monthly Notices of the Royal Astronomical Society,1977,181(3):375-389.
[20] Monaghan J J.Smoothed particle hydrodynamics[J].Annual Review of Astronomy and Astrophysics,1992,30(1):543-574.
[21] Shao J R,Li H Q,Liu G R,et al.An improved SPH method for modeling liquid sloshing dynamics[J].Computers & Structures,2012(100):18-26.
[22] Macià F,Sánchez J M,Souto‐Iglesias A,et al.WCSPH viscosity diffusion processes in vortex flows[J].International Journal for Numerical Methods in Fluids,2012,69(3):509-533.
[23] Colagrossi A,Antuono M,Le Touzé D.Theoretical considerations on the free-surface role in the smoothed-particle-hydrodynamics model[J].Physical Review E,2009,79(5):056701.
[24] Monaghan J J,Gingold R A.Shock simulation by the particle method SPH[J].Journal of Computational Physics,1983,52(2):374-389.