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1.
复杂无粘流场数值模拟的矩形/三角形混合网格技术   总被引:5,自引:0,他引:5  
张来平  张涵信 《力学学报》1998,30(1):104-108
建立了一套模拟复杂无粘流场的矩形/三角形混合网格技术,其中三角形仅限于物面附近,发挥非结构网格的几何灵活性,以少量的网格模拟复杂外型;同时在以外的区域采用矩形结构网格,发挥矩形网格计算简单快速的优势,有效地克服全非结构网格计算方法需要较大内存量和较长CPU时间的不足.混合网格系统由修正的四分树方法生成.将NND有限差分与NND有限体积格式有机地融合于混合网格计算,消除了全矩形网格模拟曲边界的台阶效应,同时保证了网格间的通量守恒.数值实验表明本方法在模拟复杂无粘流场方面的灵活性和高效性.  相似文献   

2.
基于非结构化同位网格的SIMPLE算法   总被引:5,自引:1,他引:4  
通过基于非结构化网格的有限体积法对二维稳态Navier—Stokes方程进行了数值求解。其中对流项采用延迟修正的二阶格式进行离散;扩散项的离散采用二阶中心差分格式;对于压力-速度耦合利用SIMPLE算法进行处理;计算节点的布置采用同位网格技术,界面流速通过动量插值确定。本文对方腔驱动流、倾斜腔驱动流和圆柱外部绕流问题进行了计算,讨论了非结构化同位网格有限体积法在实现SIMPLE算法时,迭代次数与欠松弛系数的关系、不同网格情况的收敛性、同结构化网格的对比以及流场尾迹结构。通过和以往结果比较可知,本文的方法是准确和可信的。  相似文献   

3.
动网格生成技术及非定常计算方法进展综述   总被引:16,自引:1,他引:16  
对应用于飞行器非定常运动的数值计算方法(包括动态网格技术和相应的数值离散格式)进行了综述.根据网格拓扑结构的不同,重点论述了基于结构网格的非定常计算方法和基于非结构/混合网格的非定常计算方法,比较了各种方法的优缺点.在基于结构网格的非定常计算方法中,重点介绍了刚性运动网格技术、超限插值动态网格技术、重叠动网格技术、滑移动网格技术等动态结构网格生成方法,同时介绍了惯性系和非惯性系下的控制方程,讨论了非定常时间离散方法、动网格计算的几何守恒律等问题.在基于非结构/混合网格的非定常计算方法中,重点介绍了重叠非结构动网格技术、重构非结构动网格技术、变形非结构动网格技术以及变形/重构耦合动态混合网格技术等方法,以及相应的计算格式,包括非定常时间离散、几何守恒律计算方法、可压缩和不可压缩非定常流动的计算方法、各种加速收敛技术等.在介绍国内外进展的同时,介绍了作者在动态混合网格生成技术和相应的非定常方法方面的研究与应用工作.  相似文献   

4.
非结构网格变形方法研究进展   总被引:13,自引:0,他引:13  
动网格技术中的非结构网格变形是计算流体力学和计算固体力学的关键技术之一. 本文在总结现有非结构网格变形方法的基础上, 提出了一种网格变形方法的详细分 类, 将现有方法归类为虚拟结构法、偏微分方程法和代数法. 本文综述了各类方法 的最新研究进展, 分析并比较了各类方法的特性, 评述了当前网格变形研究的几个 主要方向:复杂结构外形在不规则变形下的动网格生成、三维动网格生成、并行动 网格生成和动节点技术. 最后简要地探讨了该领域的发展趋势.  相似文献   

5.
谱体积方法是一种本质上解决网格依赖性的高精度CFD计算方法,本文研究了二维Euler方程的谱体积方法,提出一种基于切比雪夫多项式的单元分割方法,建立了基于WENO的变量限制器方法,并发展了结合谱体积和控制体的问题单元标记方法.采用15°超声速压缩拐角和NACA0012跨声速流动两个典型算例进行验证,结果表明,该分区方法具有更好的计算精度,标记方法可有效识别不连续区域,在较少的网格下即可获得与密网格传统有限体积法相当的计算精度.  相似文献   

6.
给出计算轴对称高速碰撞问题的拉格朗日无结构三角形网格有限体积法的并行格式,并给出以小巨型机AliantFX/40为目标计算机的算例数值模拟结果和效率分析  相似文献   

7.
采用流固耦合方法对跨音速颤振进行了数值模拟。流体方面在非结构网格上用有限体积方法求解了Euler方程;结构方面则求解了后掠机翼典型剖面的结构模态方程。时间推进采用双时间步长:对每一真实时间步,都通过基于聚合多重网格方法的伪时间步推进,对流体和结构方程交替迭代.得到一个稳态的流固耦合的解。文章最后给出了NACA64A010翼型剖面的跨音速颤振边界.与相关文献的计算结果符合良好。  相似文献   

8.
在有限元分析中,高质量的结构网格可以有效地提高有限元分析的精度,但结构网格的几何适应性差,针对复杂边界的二维计算模型,现有的方法很难自动生成高质量的结构网格;而非结构网格几何适应性很好,但存在计算效率低和精度差等问题。提出了一种新的准结构网格生成方法,能够实现复杂区域的网格自动生成并且具有高网格质量。该方法首先对计算区域运用Delaunay三角剖分技术生成粗背景网格;然后利用背景网格,使用优化的Voronoi图生成过渡的蜂巢网格;最后,通过中心圆方法对蜂巢网格单元进行结构网格剖分。分析NACA0012翼型数值模拟结果表明,提出的新准结构网格生成方法能够对边界复杂的模型自动生成高质量的网格,并且通过三种不同拓扑类型网格计算结果相互对比及与实验结果对比,证明准结构网格具有高计算精度。  相似文献   

9.
三维非结构聚合多重网格法数值模拟研究   总被引:3,自引:0,他引:3  
吕宏强  伍贻兆  夏健 《力学学报》2003,35(3):337-340
在三维非结构网格上应用聚合式多重网格技术来加速Euler方程的收敛过程.自行设计了一种高效率的网格聚合方法.采用四重三维非结构网格,在每一层网格上采用有限体积法进行计算.通过对M6翼型的数值求解验证了多重网格加速收敛的高效性.  相似文献   

10.
求解对流扩散方程的一种高效的有限体积法   总被引:1,自引:0,他引:1  
考虑无结构三角网格上求解对流扩散方程的有限体积法.引入一种梯度函数的计算方法,将现有方法中计算解变量在网格单元中心和网格单元边界的梯度的两个独立过程改造成一个过程来完成,发展了一种求解对流扩散方程的高效的有限体积法.数值实验结果表明,该方法完全达到了已有方法同样的精度,而在计算速度上有明显的提高.  相似文献   

11.
鄂秦  杨国伟  李杰 《力学学报》1996,28(6):730-735
采用保角变换与代数方法相结合,生成全场统一的贴体、正交O-H型网格.采用有限体积法求解Euler方程,模拟具有歼击机外形的全机及翼身组合体大迎角跨音速绕流.计算表明,法向力系数、气动中心位置及压力分布的计算结果与实验结果吻合良好  相似文献   

12.
In this paper, a new high‐order and high‐resolution method called the Runge–Kutta control volume discontinuous finite element method (RKCVDFEM) was proposed to solve 1D and 2D systems of hyperbolic conservation laws. Its main advantage lies in the local conservation, and it is simpler than the Runge–Kutta discontinuous Galerkin finite element method (RKDGM). The theoretical analysis showed that the RKCVDFEM has formally an optimal convergence order for 1D systems. Based on logically rectangular grids of irregular quadrilaterals, a scheme for 2D systems was constructed. Some classical problems were simulated and the validity of the method was presented. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

13.
Numerical oscillation has been an open problem for high‐order numerical methods with increased local degrees of freedom (DOFs). Current strategies mainly follow the limiting projections derived originally for conventional finite volume methods and thus are not able to make full use of the sub‐cell information available in the local high‐order reconstructions. This paper presents a novel algorithm that introduces a nodal value‐based weighted essentially non‐oscillatory limiter for constrained interpolation profile/multi‐moment finite volume method (CIP/MM FVM) (Ii and Xiao, J. Comput. Phys., 222 (2007), 849–871) as an effort to pursue a better suited formulation to implement the limiting projection in schemes with local DOFs. The new scheme, CIP‐CSL‐WENO4 scheme, extends the CIP/MM FVM method by limiting the slope constraint in the interpolation function using the weighted essentially non‐oscillatory (WENO) reconstruction that makes use of the sub‐cell information available from the local DOFs and is built from the point values at the solution points within three neighboring cells, thus resulting a more compact WENO stencil. The proposed WENO limiter matches well the original CIP/MM FVM, which leads to a new scheme of high accuracy, algorithmic simplicity, and computational efficiency. We present the numerical results of benchmark tests for both scalar and Euler conservation laws to manifest the fourth‐order accuracy and oscillation‐suppressing property of the proposed scheme. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

14.
In this work, a parallel finite volume scheme on unstructured meshes is applied to fluid flow for multidimensional hyperbolic system of conservation laws. It is based on a block-based adaptive mesh refinement strategy which allows quick meshing and easy parallelisation. As a continuation and as an extension of a previous work, the useful numerical density of entropy production is used as mesh refinement criterion combined with a local time-stepping method to preserve the computational time. Then, we numerically investigate its efficiency through several test cases with a confrontation with exact solution or experimental data.  相似文献   

15.
Computational morphodynamics in finite volume methods are based on the evaluation of the rate of bed level change in the vertices on the deforming bed. With the use of finite volume methods on collocated (unstructured) grids, the rate of bed level change needs to be interpolated from the mesh faces to the vertices. First, this work reviews two methods based on a vectorial shape of the bed evolution equation (no scalar contributions from storage, erosion and deposition) in terms of their mass conserving properties. Second, a method that allows for scalar contributions in the bed evolution equation (the Exner equation) is proposed for general, unstructured meshes, and an analytical derivation for the simple one‐dimensional problem on a non‐equidistantly discretised grid is considered. The solution is compared with the general two‐dimensional formulation. The two‐dimensional formulation leads to the formulation of a geometric sand sliding routine on unstructured grids. The newly proposed interpolation method and the sand sliding routine are tested, and mass conservation of the sediment is considered with special emphasis on the effect of the solution accuracy for the suspended sediment transport. Discussions on other interpolation methods and their mass conserving properties are given with a special focus of the distance weighted interpolation method directly available and easily applied in O penFOAM . Furthermore, effects from horizontal displacements of the vertices, explicit filtering of the evolving bed and morphological acceleration on global mass conservation, are discussed. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

16.
This paper establishes the entropy convergence of a new two-value high resolution finite volume scheme with slope relaxation for conservation laws. This scheme, motivated by the general method of high resolution schemes that have high-order accuracy in smooth regions of solutions and are free of oscillations near discontinuities, unifies and evolves slopes directly with a slope relaxation equation that governs the evolution of slopes in both smooth and discontinuous regions. Proper choices of slopes are realized adaptively via a relaxation parameter. The scheme is shown to be total-variation-bounded (TVB) stable and satisfies cell-entropy inequalities.  相似文献   

17.
The aim of this work is to develop a well‐balanced finite‐volume method for the accurate numerical solution of the equations governing suspended sediment and bed load transport in two‐dimensional shallow‐water flows. The modelling system consists of three coupled model components: (i) the shallow‐water equations for the hydrodynamical model; (ii) a transport equation for the dispersion of suspended sediments; and (iii) an Exner equation for the morphodynamics. These coupled models form a hyperbolic system of conservation laws with source terms. The proposed finite‐volume method consists of a predictor stage for the discretization of gradient terms and a corrector stage for the treatment of source terms. The gradient fluxes are discretized using a modified Roe's scheme using the sign of the Jacobian matrix in the coupled system. A well‐balanced discretization is used for the treatment of source terms. In this paper, we also employ an adaptive procedure in the finite‐volume method by monitoring the concentration of suspended sediments in the computational domain during its transport process. The method uses unstructured meshes and incorporates upwinded numerical fluxes and slope limiters to provide sharp resolution of steep sediment concentrations and bed load gradients that may form in the approximate solutions. Details are given on the implementation of the method, and numerical results are presented for two idealized test cases, which demonstrate the accuracy and robustness of the method and its applicability in predicting dam‐break flows over erodible sediment beds. The method is also applied to a sediment transport problem in the Nador lagoon.Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

18.
In this work, we present a fast and parallel finite volume scheme on unstructured meshes applied to complex fluid flow. The mathematical model is based on a three-dimensional compressible low Mach two-phase flows model, combined with a linearised ‘artificial pressure’ law. This hyperbolic system of conservation laws allows an explicit scheme, improved by a block-based adaptive mesh refinement scheme. Following a previous one-dimensional work, the useful numerical density of entropy production is used as mesh refinement criterion. Moreover, the computational time is preserved using a local time-stepping method. Finally, we show through several test cases the efficiency of the present scheme on two- and three-dimensional dam-break problems over an obstacle.  相似文献   

19.
The discontinuous Galerkin (DG) and spectral volume (SV) methods are two recently developed high‐order methods for hyperbolic conservation laws capable of handling unstructured grids. In this paper, their overall performance in terms of efficiency, accuracy and memory requirement is evaluated using a 2D scalar conservation laws and the 2D Euler equations. To measure their accuracy, problems with analytical solutions are used. Both methods are also used to solve problems with strong discontinuities to test their ability in discontinuity capturing. Both the DG and SV methods are capable of achieving their formal order of accuracy while the DG method has a lower error magnitude and takes more memory. They are also similar in efficiency. The SV method appears to have a higher resolution for discontinuities because the data limiting can be done at the sub‐element level. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

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