共查询到14条相似文献,搜索用时 46 毫秒
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基于有限体积法的非结构网格大涡模拟离散方法研究 总被引:1,自引:1,他引:0
非结构网格下的大涡模拟是解决复杂几何体高Reynolds(雷诺)数流动的有效途径.首先,基于有限体积法,研究了对流项和扩散项非结构网格下的离散方法.研究结果表明:基于TVD(total variation diminishing)限制器的限制中心差分格式保证了对流项的二阶精度并抑制了非物理振荡,同时,线性迎风格式虽然稳定,但数值耗散过大,且不能保证有界,中心差分格式引起了周期性非物理振荡;扩散项的超松弛非正交修正减小了网格非正交带来的离散误差,但修正系数须根据网格非正交的程度进行合理选取.为验证所述离散方法对大涡模拟的适用性,数值计算了Re=1.14×10~6下的非定常三维小球绕流,计算方法包括:计算网格用基于Delaunay三角剖分和Netgen前沿推进算法的四面体非结构网格;湍流模型用改进的延迟分离涡大涡模型;在离散格式的选取上,对流项用限制中心差分,扩散项加入非正交修正,插值格式用最小二乘法,时间项用二阶后向差分.计算结果表明,所用离散方法稳定收敛并且与实验数据基本吻合. 相似文献
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并列双方柱绕流的大涡模拟及频谱分析 总被引:4,自引:0,他引:4
应用二阶全展开ETG有限元离散格式与大涡模拟相结合的方法,对间距比为1.5情况下的并列双方柱绕流进行了数值模拟.由王小华、何钟怡提出的二阶全展开ETG有限元方法通过对N-S方程中的时变项进行Taylor展开,从而把时间导数用空间导数来代替,其作用相当于引入了人工粘性.计算得到了不同时刻的流线图,给出了两方柱的阻力系数、升力系数以及两对称点上流向速度随时间的变化历程,并采用谱分析的方法研究了对称边界条件下并列双方柱绕流的频谱对称性问题.为了消除初始条件的影响,在所取样本中去除了计算中初始段的数据,分别分析了阻力系数、升力系数以及两对称点上流向速度的频谱.结果表明:对称边界条件下,双方柱绕流运动参量的时域过程虽然是不对称的,但频域过程却是对称的. 相似文献
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直接数值模拟/大涡模拟中数值误差影响的研究 总被引:1,自引:0,他引:1
通过比较湍流的能谱和总动能,对数值误差(包括混淆误差、离散截断误差)、亚格子模型以及它们之间相互作用对直接数值模拟和大涡模拟的影响进行了系统研究.算例采用了三维各向均匀同性湍流.为了研究复杂几何形状,数值格式采用了谱方法和Pade紧致格式.大涡模型采用了truncated Navior-Stokes(TNS)模型结合Pade离散滤波器.结果表明直接数值模拟中离散误差对结果有很大影响,低阶格式会导致计算发散.而大涡模拟中亚格子模型不仅能表征小尺度对大尺度的影响,而且还缓解了数值误差对计算结果的影响.因而低精度格式也可取得不错的结果. 相似文献
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A low-dispersive dynamic finite difference scheme for Large-Eddy Simulation is developed. The dynamic scheme is constructed by combining Taylor series expansions on two different grid resolutions. The scheme is optimized dynamically through the real-time adaption of a dynamic coefficient according to the spectral content of the flow, such that the global dispersion error is minimal. In the case of DNS-resolution, the dynamic scheme reduces to the standard Taylor-based finite difference scheme with formal asymptotic order of accuracy. When going to LES-resolution, the dynamic scheme seamlessly adapts to a dispersion-relation preserving scheme. The scheme is tested for Large-Eddy Simulation of Burgers equation. Very good results are obtained. 相似文献
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对一类多体气动弹性系统超声速颤振问题进行研究.分别采用多体动力学理论、活塞理论建立了弹性结构系统的动力学模型与超声速非定常气动力模型,得到了由微分代数方程表示的多体系统气动弹性动力学方程.通过数值求解微分代数方程的特征值问题,研究了多体系统在平衡位置小扰动运动的稳定性,完成了多体气动弹性系统超声速颤振分析.应用该方法研究了板状翼面及含操纵面翼面的超声速颤振问题,并得到了操纵面处于不同位置时翼面的颤振速度.结果表明,所发展的多体气动弹性系统超声速颤振分析方法,适用于由多个部件组成的工程结构颤振分析. 相似文献
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Yu. N. Sadkov 《Computational Mathematics and Modeling》2004,15(4):344-349
The oscillations of free supersonic jets are simulated using the axisymmetric Euler equation model. A third order accurate through difference scheme with artificial viscosity is used. Jet flows from a sonic nozzle with nozzle-to-ambient pressure ratio between 1.2 and 2 are investigated. The numerical results are compared with physical experiments. 相似文献
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Use of numerical experiment methods gives broad opportunities for studying complex flows by rather simple and inexpensive means. This work is devoted to researches on aerodynamic interference of bodies in supersonic flows. Interest to similar problems is shown in a number of areas of modern mechanics: meteoritics, movement of multiphase media, applied fields. The head shock wave before a configuration of spheres with growth of distance h monotonously breaks up to individual shock waves before spheres of forward lines. The basic conclusion of this research is the following: distortion of supersonic stream around systems of bodies as though is transferred downstream, i.e. the influence of back bodies on the flow nearby forward bodies is small. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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R. G. Coyle 《The Journal of the Operational Research Society》1976,27(1):134-135
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The Approximate Deconvolution Model (ADM) for Large–Eddy Simulation is an approach for the computation of turbulent flows. The main idea of ADM is to approximate the unfiltered data in the filtered Navier–Stokes equations by deconvolution of filtered values. This is achieved via repeated filtering. Thereby problems may arise for cases where the order of the spatial discretisation scheme is too low or lower than the order of the filter operation. The interaction of the discretisation and the filtering was investigated for one–dimensional forced Burgers turbulence. For this study, both the order of the filter operator and the order of the spatial discretisation of the derivatives were varied independently. It was found that the use of ADM with low–order discretisation schemes can not be recommended. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献