含运动边界钝体绕流风场的大涡模拟数值算法
发布时间：2018-09-17 06:39
【摘要】：薄膜屋盖结构与风场之间的流固耦合作用是影响结构风振响应的重要因素。数值模拟是流固耦合研究的重要手段,准确模拟流体域的时变特性是掌握流固耦合效应产生机理和发展规律的前提。风与薄膜结构流固耦合运动中的流体域是含动边界的钝体绕流近地风场,在采用计算流体动力学(Computational Fluid Dynamics,CFD)技术对其进行大涡模拟(Large-eddy Simulation, LES)数值近似计算时,仍存在一些亟待解决的问题。 建立适于大型工程应用的亚格子模型是大涡模拟方法理论研究中的热点问题之一。在求解近地风场大涡模拟控制方程时,投影法是一种高效的压力速度解耦算法。目前大多数投影格式对压力的计算在时间方向上比速度的计算至少低一阶精度,而压力场的时间精度将直接影响流固耦合效应的计算精度。因此,投影法的压力时问精度还有待提高。此外,动边界绕流模拟适宜在任意拉格朗日欧拉(Arbitrary Lagrangian Eulerian, ALE)动态网格框架下进行。模拟过程中网格更新频繁,其几何品质和更新前后的一致性是影响模拟精度的重要因素。目前大部分动网格更新算法仅关注更新后网格的几何品质,对更新前后网格一致性的测试不够；而动网格更新算法的计算耗时也是需要考虑的一个课题。 针对上述问题,本文对亚格子模型、投影法及其在ALE动态网格下的应用以及动网格更新技术等内容进行了理论和数值研究,开展的研究工作和提出的解决方案主要包括： 1、亚格子模型的测试和对比。在阐述近地风场的大涡模拟无量纲控制方程以及多种亚格子模型的构造过程后,在笛卡尔静态网格下编制了方程求解程序。以该程序为计算平台,对多种亚格子模型的适用性、准确性和计算效率进行了测试。结果表明,钝体绕流风场的大涡模拟工程应用中可以采用阻尼修正的标准S模型。 2、动态网格下数值求解方法的建立。以ALE描述为基础,在动态网格下建立了大涡模拟控制方程(下文简称ALE-LES方程),并对方程中的网格运动参数和流动参数进行解耦,建立了交错求解方程的数值计算方法。期间,为提高数值方法的时间计算精度,构造了压力和速度能达到同一高阶时间精度的全精度连续投影方法,并将其与求解网格运动的二阶预测校正格式相结合,得到了ALE-LES方程的全二阶精度投影格式。将建立的数值求解方法进行坐标转换,在贴体坐标系下编制了ALE-LES方程求解程序的核心模块。 3、动网格更新算法的对比研究。归纳整理出网格质量评价模型,并据此在两种畸变网格算例中,为适用于结构网格的多种动网格更新算法对网格几何品质的改善力度进行了对比；同时,对不同算法在更新前后网格的一致性和计算效率方面进行了测试,指出九点网格重构法综合性能最为优异。将九点网格重构法扩展到三维研究领域并更名为距离加权法,据此编制了网格动态更新子程序模块。 4、数值模拟程序的开发和验证。将亚格子模型子程序模块和网格动态更新子程序模块与求解ALE-LES方程的核心程序相结合,开发了适用于模拟含运动边界钝体绕流风场的CFD计算程序。分别以二维方腔驱动流和Taylor涡列问题验证了程序的稳定性和时间计算精度。 5、振动屋盖绕流特性的数值分析。以下部封闭式大跨度平屋盖结构为研究对象,应用本文开发程序,对屋盖以二阶谐波模态振动时的结构绕流场进行了数值模拟,通过与相同尺寸刚性屋盖结构绕流模拟结果的对比分析,研究了屋盖的振动对模型表面风压系数分布和绕流场流动结构的影响。结果表明,屋盖振动是影响建筑结构表面平均、脉动风压系数的重要因素；屋盖振动导致绕流场旋涡结构复杂化,特征湍流度增加；屋盖的振动对绕流场瞬时风压分布的影响明显,二阶谐波模态的振动形式容易引发脉动风与屋盖的共振,不利于屋盖的抗风稳定。自主开发程序的成功应用表明了该程序可作为薄膜结构流固耦合效应数值模拟计算平台的流体域求解器。
[Abstract]:Fluid-structure interaction between membrane roof structure and wind field is an important factor affecting the wind-induced vibration response of structures.Numerical simulation is an important means of fluid-structure coupling research.Accurate simulation of time-varying characteristics of fluid domain is the premise to grasp the generation mechanism and development law of fluid-structure coupling effect. Computational Fluid Dynamics (CFD) technique is used to approximate the large eddy simulation (LES) of a blunt body with moving boundary.
Establishing a sublattice model suitable for large-scale engineering applications is one of the hot issues in the theoretical study of large eddy simulation. Projection method is an efficient pressure-velocity decoupling algorithm for solving the large eddy simulation control equations in the near-Earth wind field. In addition, the simulation of flow around moving boundary is suitable for arbitrary Lagrangian Eulerian (ALE) dynamic grids. In the simulation process, the grid update frequency is used. At present, most of the dynamic mesh updating algorithms only focus on the geometric quality of the updated mesh, and the test of the consistency before and after updating is insufficient. The computational time-consuming of the dynamic mesh updating algorithm is also a problem to be considered.
In view of the above problems, the subgrid model, projection method and its application in ALE dynamic mesh and dynamic mesh updating technology are studied theoretically and numerically in this paper.
1. Sublattice model test and comparison. After explaining the large eddy simulation dimensionless governing equations of the near-Earth wind field and the construction process of several sublattice models, the equation solving program is compiled under the Cartesian static grid. The results show that the standard S model with damping modification can be used in large eddy simulation of wind field around bluff body.
2. Establishment of numerical solution method in dynamic grid. Based on ALE description, large eddy simulation control equation (hereinafter referred to as ALE-LES equation) is established in dynamic grid, and the grid motion parameters and flow parameters in the equation are decoupled. A numerical method for solving the equation is established. During this period, the timescale of the numerical method is improved. A full-precision continuous projection method with the same high-order time precision for pressure and velocity is constructed, and the second-order accurate projection scheme for ALE-LES equation is obtained by combining it with the second-order predictive correction scheme for grid motion. The numerical solution method is transformed into coordinates and AL is programmed in body-fitted coordinates. The core module of E-LES equation solver.
3. Comparisons of dynamic mesh updating algorithms. The mesh quality evaluation models are summarized and sorted out. Based on these two distorted mesh examples, the improvement of the mesh geometry quality is compared for various dynamic mesh updating algorithms suitable for structured meshes. At the same time, the consistency and computational efficiency of different algorithms before and after updating are compared. The nine-point mesh reconstruction method is extended to the three-dimensional research field and renamed as the distance-weighted method. Based on this, a dynamic mesh update subroutine module is developed.
4. Development and verification of numerical simulation program. Combining sublattice model subroutine module and grid dynamic updating subroutine module with the core program for solving ALE-LES equation, a CFD program for simulating the wind field around a bluff body with moving boundary is developed. The program is verified by two-dimensional square cavity driving flow and Taylor vortex train problem respectively. The stability and the accuracy of time calculation.
5. Numerical analysis of the flow around a vibrating roof. The following closed large-span flat roof structure is studied. The numerical simulation of the flow around the roof under the second harmonic mode vibration is carried out by using the program developed in this paper. The vibration of the roof is studied by comparing with the results of the flow around a rigid roof structure of the same size. The results show that the roof vibration is an important factor affecting the average and fluctuating wind pressure coefficients on the surface of the structure; the vibration of the roof results in the complexity of the vortex structure around the flow field and the increase of the characteristic turbulence; the vibration of the roof has an obvious effect on the instantaneous wind pressure distribution around the flow field. The second-order harmonic modes are liable to cause the resonance between the fluctuating wind and the roof, which is not conducive to the wind stability of the roof.
【学位授予单位】：北京交通大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TU312.1
[Abstract]:Fluid-structure interaction between membrane roof structure and wind field is an important factor affecting the wind-induced vibration response of structures.Numerical simulation is an important means of fluid-structure coupling research.Accurate simulation of time-varying characteristics of fluid domain is the premise to grasp the generation mechanism and development law of fluid-structure coupling effect. Computational Fluid Dynamics (CFD) technique is used to approximate the large eddy simulation (LES) of a blunt body with moving boundary.
Establishing a sublattice model suitable for large-scale engineering applications is one of the hot issues in the theoretical study of large eddy simulation. Projection method is an efficient pressure-velocity decoupling algorithm for solving the large eddy simulation control equations in the near-Earth wind field. In addition, the simulation of flow around moving boundary is suitable for arbitrary Lagrangian Eulerian (ALE) dynamic grids. In the simulation process, the grid update frequency is used. At present, most of the dynamic mesh updating algorithms only focus on the geometric quality of the updated mesh, and the test of the consistency before and after updating is insufficient. The computational time-consuming of the dynamic mesh updating algorithm is also a problem to be considered.
In view of the above problems, the subgrid model, projection method and its application in ALE dynamic mesh and dynamic mesh updating technology are studied theoretically and numerically in this paper.
1. Sublattice model test and comparison. After explaining the large eddy simulation dimensionless governing equations of the near-Earth wind field and the construction process of several sublattice models, the equation solving program is compiled under the Cartesian static grid. The results show that the standard S model with damping modification can be used in large eddy simulation of wind field around bluff body.
2. Establishment of numerical solution method in dynamic grid. Based on ALE description, large eddy simulation control equation (hereinafter referred to as ALE-LES equation) is established in dynamic grid, and the grid motion parameters and flow parameters in the equation are decoupled. A numerical method for solving the equation is established. During this period, the timescale of the numerical method is improved. A full-precision continuous projection method with the same high-order time precision for pressure and velocity is constructed, and the second-order accurate projection scheme for ALE-LES equation is obtained by combining it with the second-order predictive correction scheme for grid motion. The numerical solution method is transformed into coordinates and AL is programmed in body-fitted coordinates. The core module of E-LES equation solver.
3. Comparisons of dynamic mesh updating algorithms. The mesh quality evaluation models are summarized and sorted out. Based on these two distorted mesh examples, the improvement of the mesh geometry quality is compared for various dynamic mesh updating algorithms suitable for structured meshes. At the same time, the consistency and computational efficiency of different algorithms before and after updating are compared. The nine-point mesh reconstruction method is extended to the three-dimensional research field and renamed as the distance-weighted method. Based on this, a dynamic mesh update subroutine module is developed.
4. Development and verification of numerical simulation program. Combining sublattice model subroutine module and grid dynamic updating subroutine module with the core program for solving ALE-LES equation, a CFD program for simulating the wind field around a bluff body with moving boundary is developed. The program is verified by two-dimensional square cavity driving flow and Taylor vortex train problem respectively. The stability and the accuracy of time calculation.
5. Numerical analysis of the flow around a vibrating roof. The following closed large-span flat roof structure is studied. The numerical simulation of the flow around the roof under the second harmonic mode vibration is carried out by using the program developed in this paper. The vibration of the roof is studied by comparing with the results of the flow around a rigid roof structure of the same size. The results show that the roof vibration is an important factor affecting the average and fluctuating wind pressure coefficients on the surface of the structure; the vibration of the roof results in the complexity of the vortex structure around the flow field and the increase of the characteristic turbulence; the vibration of the roof has an obvious effect on the instantaneous wind pressure distribution around the flow field. The second-order harmonic modes are liable to cause the resonance between the fluctuating wind and the roof, which is not conducive to the wind stability of the roof.
【学位授予单位】：北京交通大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TU312.1
【参考文献】
相关期刊论文 前10条
1 王兵,张会强,王希麟,郭印诚,林文漪;不同亚格子模式在后台阶湍流流动大涡模拟中的应用[J];工程热物理学报;2003年01期
2 王坪;田振夫;;基于投影法求解不可压缩流的高精度紧致格式[J];工程数学学报;2010年02期
3 李启;杨庆山;朱伟亮;;湍流入口条件下建筑非定常风场的大涡模拟[J];工程力学;2012年12期
4 周红梅;于胜春;高R，
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