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排序方式: 共有616条查询结果,搜索用时 15 毫秒
111.
本文开发了一套基于非结构网格的间断有限元方法(DG)程序,并对与单元形状无关的斜率限制器进行了研究。此程序支持多种网格类型,能够方便应用于具有混合单元的非结构网格,具有处理复杂几何结构的能力,为研究叶轮机械内部复杂流动现象提供了有效的研究工具。本文利用该程序对若干典型无黏和黏性问题进行数值模拟,结果表明,该程序具有较高的可信度,能够处理具有混合单元的非结构网格,并给出良好的数值模拟结果。 相似文献
112.
A new numerical method named as basic function method is proposed. It can directly discretize differential operators on unstructured grids. By expanding the basic function to approach the exact function, the central and upwind schemes of derivative are constructed. By using the second-order polynomial as a basic function and applying the flux splitting method and the combination of central and upwind schemes to suppress non-physical fluctuation near shock waves, a second-order basic function scheme of polynomial type is proposed to solve inviscid compressible flows numerically. Numerical results of typical examples for two-dimensional inviscid compressible transonic and supersonic steady flows indicate that the new scheme has high accuracy and high resolution for shock waves. Combined with the adaptive remeshing technique, satisfactory results can be obtained. 相似文献
113.
Smoothness of Stationary Subdivision on Irregular Meshes 总被引:2,自引:0,他引:2
D. Zorin 《Constructive Approximation》2000,16(3):359-398
We derive necessary and sufficient conditions for tangent plane and C
k
-continuity of stationary subdivision schemes near extraordinary vertices. Our criteria generalize most previously known
conditions. We introduce a new approach to analysis of subdivision surfaces based on the idea of the universal surface . Any subdivision surface can be locally represented as a projection of the universal surface, which is uniquely defined
by the subdivision scheme. This approach provides us with a more intuitive geometric understanding of subdivision near extraordinary
vertices.
February 16, 1998. Date revised: January 27, 1999. Date accepted: April 2, 1999. 相似文献
114.
F. Fang C. C. Pain I. M. Navon M. D. Piggott G. J. Gorman P. A. Allison A. J. H. Goddard 《国际流体数值方法杂志》2009,59(8):827-851
A novel proper orthogonal decomposition (POD) model has been developed for use with an advanced unstructured mesh finite‐element ocean model, the Imperial College Ocean Model (ICOM, described in detail below), which includes many recent developments in ocean modelling and numerical analysis. The advantages of the POD model developed here over existing POD approaches are the ability:
- 1. To increase accuracy when representing geostrophic balance (the balance between the Coriolis terms and the pressure gradient). This is achieved through the use of two sets of geostrophic basis functions where each one is calculated by basis functions for velocities u and v.
- 2. To speed up the POD simulation. To achieve this a new numerical technique is introduced, whereby a time‐dependent matrix in the discretized equation is rapidly constructed from a series of time‐independent matrices. This development imparts considerable efficiency gains over the often‐used alternative of calculating each finite element over the computational domain at each time level.
- 3. To use dynamically adaptive meshes in the above POD model.
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118.
B. Bouzouf D. Ouazar M. Himi A. Casas I. Elmahi F. Benkhaldoun 《Transport in Porous Media》2001,43(1):179-194
In this paper, hydrogeological and geophysical data are used to validate a numerical model developed to predict seawater intrusion into coastal aquifers. The cell-centered finite volume method is adopted here to solve the set of coupled partial differential equations describing the motion of saltwater and freshwater separated by a sharp interface. These equations are based on the Dupuit approximation and are obtained from integration of 3D flow equations for fresh and salt water zones over the vertical dimension. In order to have flexibility upon complex configurations domain, non structured grid meshing is utilized. To approximate the diffusion fluxes, Green-Gauss type reconstruction, based on diamond-cell and least squares interpolation, is performed. The model is first validated using academic test case studies with known closed form solutions. The mathematical model has been calibrated using hydrogeochemical and geophysical data. The geophysical method applied in this study has been a frequency domain electromagnetic method. In this method the apparent electrical conductivity is measured by induction using two separate hand-held transmitter and receiver coils. During the operation the transmitter coil is energized by a low frequency alternating current that radiates an electromagnetic field and the receiver coil detects the resulting field. Taking into account the relationship between the bulk conductivity of the subsoil and the conductivity of groundwater, EM soundings have been interpreted to provide complementary information to hydrogeochemical data to outline the fresh–saltwater interface. This methodology has been applied to the case of saltwater intrusion into the Llobregat delta aquifer, near Barcelona, Spain. 相似文献
119.
不可压N-S方程高效算法及二维槽道湍流分析 总被引:6,自引:1,他引:5
构造了基于非等距网格的迎风紧致格式,并将其与三阶精度的Adams半隐方法相结合,构造了求解不可压N-S方程高效算法。该算法利用基于交错网格的离散形式的压力Poisson方程求解压力项,解决了边界处的残余散度问题;同时还利用快速Fourier变换将方程的隐式部分解耦,离散后的代数方程组利用追赶法求解,大大减少了计算量。通过对二维槽道流动的数值模拟,证实了所构造的数值方法具有精度高,稳定性好,能抑制混淆误差等优点,同时具有很高的计算效率,是进行壁湍流直接数值模拟的有效方法。在数值模拟的基础上对二维槽道流动进行了分析,得到了Reynolds数从6000到15000的二维流动饱和态解(所谓“二维槽道湍流”);定性及定量结果均与他人的数值计算结果吻合十分理想。对流场进行了分析,指出了“二维湍流”与三维湍流统计特性的区别。 相似文献
120.