共查询到18条相似文献,搜索用时 156 毫秒
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对于粘性绕流的数值模拟,在自适应直角网格基础上,结合三角形非结构网格和结构化网格,利用其各自的优势和特点,提出一种生成混合杂交网格的思路和方法.在物面附近生成适合粘性流计算的大长宽比结构化网格,在远场分布自适应直角网格,快速离散计算空间.对于复杂的多体问题,采用三角形网格来连接各体网格,并运用网格合并的方法,保证各网格之间的光滑过渡与连接,提高网格质量.针对一些二维、三维外形的绕流问题,在上述网格基础上,采用B-L代数湍流模型和中心有限体积法,完成Navier-Stokes和Euler方程数值模拟的对比计算,结果表明网格生成和流场计算是正确的. 相似文献
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二维非结构网格生成及Euler方程计算的方法研究 总被引:2,自引:0,他引:2
用离翼型表面最小作为阵面推进法中的参数选择依据。生成二维问题的非结构网格。这种方法戏了传统的背景网格观念,直接提供网格生成过程中所需的背景信息。在求解Eluer方程时,用格心格式的有限体积法作空间离散,用四步Runge-Kutta作时间推进,采用不同的加速收敛措施获得定常流动。提出了两这界条件的构造办法,并 不同边界条件对结果的影响。 相似文献
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用多重网格技术求解平面叶栅跨音绕流 总被引:1,自引:0,他引:1
1982年以来,Ni、Davis等人发展了一种与多重网格技术相结合的时间相关有限体积积分方法,这是一个快速求定常解的显式推进方法。本文采用这种方法计算平面叶栅跨音绕流,阐明了Ni-Davis格式的基本思想和处理原则,在物面边界近似处理上本文作了适当改进,为适当选取人工粘性项提出了具体平滑公式,又根据数值试验对多重网格技术提出了改进算法。两个跨音叶栅绕流算例表明,数值结果的精度和计算效率是令人满意的,可以满足航空发动机气动设计的需要。在IBM 4341计算机上,求解一个65×17网格上的跨音流场大约需CPU时间15分钟,使用四层网格技术后可节省CPU时间50%到60%。 相似文献
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嵌套网格技术中的Collar网格和虚拟网格方法 总被引:3,自引:0,他引:3
针对嵌套网格技术中的结合部问题,提出了Collar网格和虚拟网格方法.用双曲型微分方程生成的处于结合部的有两个边界分别处于不同固定曲面上的Collar网格,在保证计算网格的生成方便快捷而且网格质量高的前提下,解决了为物体结合部的内外边界点提供有效插值单元的问题.虚拟网格为紧贴物面的面网格,它的作用是将物面边界条件传递给其它网格的边界面,而其本身不作流场计算.计算实践表明,将Collar网格和虚拟网格结合起来应用在嵌套网格技术中能保证几何外形不发生变化,有效地处理各种复杂组合体外形的结合部问题. 相似文献
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三维复杂外形的非结构网格自动生成技术与应用 总被引:2,自引:1,他引:1
给出了一套三菜的非结构网络自动生成方法。任意外形由几种代表性的曲线和曲面来描述,将曲面变换为平面,在平面内由二维阵面推进法生成三角形网格,然后反变换为物形表面网格。空间的四面体网格由三维阵面推进法生成。四面体网格的优化采用了附加“关联质量”约束的节点松驰的局部的Delaunay变换技术。另外还发展了非结构风格的自适应技术。数值算例表明了方法的灵活性和通用性 相似文献
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研究如何在非结构网格上进行Navier Stokes(N-S)方程湍流计算.采用格心有限体积方法离散N-S方程.为了适应非结构网格,计算所用的湍流模型特别选用Baldwin Barth(B-B)单方程模型.此模型由一个单一的具有源项的对流扩散方程组成.为了能在非结构网格上求解B B单方程模型,提出一显式有限体积格式,并直接对带源项的格式进行稳定性分析,得到了相应的时间步长限制条件.最后以平板、RAE 2822翼型、多段翼型绕流等数值算例验证了计算方法的有效性. 相似文献
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在动态网格上通过耦合求解流动控制方程和结构动力学方程, 发展了一种舵面控制下飞行器运动响应过程中气动弹性数值模拟研究方法.流动控制方程采用N-S方程, 结构动力学采用线性模态叠加方法, 其中流动控制方程空间离散采用基于非结构网格的有限体积方法, 对流通量采用计算HLLC格式, 非定常时间离散采用基于LU-SGS的双时间步长方法.模拟中, 气动运动和结构变形在双时间步长方法推进过程中采用改进松耦合方法, 气动网格与结构网格之间信息交换采用无限平板样条法实现, 飞行器的运动和变形采用基于重叠网格和Delaunay图映射变形网格相结合的方法进行处理.采用多个考核算例对发展的数值方法进行考核验证, 结果表明该方法可以高效精确模拟舵面开环控制下飞行器运动响应过程中的气动弹性特性. 相似文献
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将龙格库塔间断有限元方法(RDDG)与自适应方法相结合,求解三维欧拉方程.区域剖分采用非结构四面体网格,依据数值解的变化采用自适应技术对网格进行局部加密或粗化,减少总体网格数目,提高计算效率.给出四种自适应策略并分析不同自适应策略的优缺点.数值算例表明方法的有效性. 相似文献
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Basic function method is developed to treat the incompressible viscous flow. Artificial compressibility coefficient, the technique
of flux splitting method and the combination of central and upwind schemes are applied to construct the basic function scheme
of trigonometric function type for solving three-dimensional incompressible Navier-Stokes equations numerically. To prove
the method, flows in finite-length-pipe are calculated, the velocity and pressure distribution of which solved by our method
quite coincide with the exact solutions of Poiseuille flow except in the areas of entrance and exit. After the method is proved
elementary, the hemodynamics in two- and three-dimensional aneurysms is researched numerically by using the basic function
method of trigonometric function type and unstructured grids generation technique. The distributions of velocity, pressure
and shear force in steady flow of aneurysms are calculated, and the influence of the shape of the aneurysms on the hemodynamics
is studied.
Supported by the National Natural Foundation of China (Grant Nos. 40874077, 40504020, and 40536029) and the National Basic
Research Program of China (Grant No. 2006CB806304) 相似文献
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Sourabh V. Apte Krishnan Mahesh Parviz Moin 《Proceedings of the Combustion Institute》2009,32(2):2247-2256
Large-eddy simulation of an evaporating isopropyl alcohol spray in a coaxial combustor is performed. The Favre-averaged, variable density, low-Mach number Navier-Stokes equations are solved on unstructured grids with dynamic subgrid scale model to compute the turbulent gas-phase. The original incompressible flow algorithm for LES on unstructured grids by [Mahesh et al., J. Comp. Phys. 197 (2004) 215–240] is extended to include density variations and droplet evaporation. An efficient particle-tracking scheme on unstructured meshes is developed to compute the dispersed phase. Experimentally measured droplet size distribution and size-velocity correlation near the nozzle exit are used as the inlet conditions for the spray. The predictive capability of the LES approach on unstructured grids together with Lagrangian droplet dynamics models to capture the droplet dispersion characteristics, size distributions, and the spray evolution is examined in detail. The mean and turbulent quantities for the gas and particle phases are compared to experimental data to show good agreement. It is shown that for low evaporation rates considered in the present study, a well resolved large-eddy simulation together with simple subgrid models for droplet evaporation and motion provides good agreement of the mean and turbulent quantities for the gas and droplet phases compared to the experimental data. This work represents an important first step to assess the predictive capability of the unstructured grid LES approach applied to spray vaporization. The novelty of the results presented is that they establish a baseline fidelity in the ability to simulate complex flows on unstructured grids at conditions representative of gas-turbine combustors. 相似文献
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We study a 3-dimensional, dual-field, fully explicit method for the solution of Maxwell's equations in the time domain on unstructured, tetrahedral grids. The algorithm uses the element level time domain (ELTD) discretization of the electric and magnetic vector wave equations. In particular, the suitability of the method for the numerical analysis of nanometer structured systems in the optical region of the electromagnetic spectrum is investigated. The details of the theory and its implementation as a computer code are introduced and its convergence behavior as well as conditions for stable time domain integration is examined. Here, we restrict ourselves to non-dispersive dielectric material properties since dielectric dispersion will be treated in a subsequent paper. Analytically solvable problems are analyzed in order to benchmark the method. Eventually, a dielectric microlens is considered to demonstrate the potential of the method. A flexible method of 2nd order accuracy is obtained that is applicable to a wide range of nano-optical configurations and can be a serious competitor to more conventional finite difference time domain schemes which operate only on hexahedral grids. The ELTD scheme can resolve geometries with a wide span of characteristic length scales and with the appropriate level of detail, using small tetrahedra where delicate, physically relevant details must be modeled. 相似文献