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1.
Sutthisak Phongthanapanich Suthee Traivivatana Parinya Boonmaruth Pramote Dechaumphai 《Acta Mechanica Sinica》2006,22(2):138-147
Based on flux-based formulation, a nodeless variable element method is developed to analyze two-dimensional steady-state and
transient heat transfer problems. The nodeless variable element employs quadratic interpolation functions to provide higher
solution accuracy without necessity to actually generate additional nodes. The flux-based formulation is applied to reduce
the complexity in deriving the finite element equations as compared to the conventional finite element method. The solution
accuracy is further improved by implementing an adaptive meshing technique to generate finite element mesh that can adapt
and move along corresponding to the solution behavior. The technique generates small elements in the regions of steep solution
gradients to provide accurate solution, and meanwhile it generates larger elements in the other regions where the solution
gradients are slight to reduce the computational time and the computer memory. The effectiveness of the combined procedure
is demonstrated by heat transfer problems that have exact solutions. These problems are: (a) a steady-state heat conduction
analysis in a square plate subjected to a highly localized surface heating, and (b) a transient heat conduction analysis in
a long plate subjected to a moving heat source.
The English text was polished by Yunming Chen. 相似文献
2.
Accurate modeling of interfacial flows requires a realistic representation of interface topology. To reduce the computational effort from the complexity of the interface topological changes, the level set method is widely used for solving two‐phase flow problems. This paper presents an explicit characteristic‐based finite volume element method for solving the two‐dimensional level set equation. The method is applicable for the case of non‐divergence‐free velocity field. Accuracy and performance of the proposed method are evaluated via test cases with prescribed velocity fields on structured grids. By given a velocity field, the motion of interface in the normal direction and the mean curvature, examples are presented to demonstrate the performance of the proposed method for calculating interface evolutions in time. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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S. Phongthanapanich & P. Dechaumphai 《International Journal of Computational Fluid Dynamics》2013,27(8):631-640
A Roe's flux-difference splitting scheme, combining with the entropy fix method according to Van Leer et al., and the H-correction entropy fix method by Pandolfi and D'Ambrosio, is proposed. The presented scheme eliminates unphysical flow behaviors such as a spurious bump of the carbuncle phenomenon that occurs on the bow shock from flow over a blunt body, and the expansion shock generated from flow over a forward facing step. The proposed scheme is further extended to obtain high-order spatial and temporal solution accuracy. The scheme is, in addition, combined with an adaptive meshing technique that generates unstructured triangular meshes to resemble the flow phenomena for reducing computational effort. The entire procedure is evaluated by solving several benchmarks as well as complex steady-state and transient high-speed compressible flow problems. 相似文献
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The carbuncle phenomenon normally occurs numerically in the prediction of shock waves in flow computation. Most efforts to remedy this problem concern numerical treatment of the bow shock wave while many evidences declare that the carbuncle phenomenon problem may be unsolvable. This paper studies the numerical instability of the AUSM+ scheme on two-dimensional structured triangular grids. By examining several test cases, it is found that the scheme cannot satisfy robustness against shock-induced anomalies. A more stable version of the AUSM+ scheme (so-called AUSM+δ scheme) is developed by applying the multidimensional dissipation technique to the numerical dissipation term in order to alleviate the shock instability. The dissipation mechanism against perturbations is investigated by applying a linearised discrete analysis to the odd--even decoupling problem. The recursive equations show that the AUSM+δ scheme is less sensitive to such anomalies than the original scheme. Finally, the scheme is further extended to achieve the second-order solution accuracy and evaluated by solving several test cases. 相似文献
6.
A nodeless variable element method with the fluxbased formulation is developed to analyze two-dimensional thermal-structural problems. The nodeless variable formula- tion provides accurate temperature distributions to yield more accurate thermal stress solutions. The flux-based formulation is used to reduce the complexity in deriving the finite element equations as compared to the conventional finite element method. The solution accuracy is further improved by implementing an adaptive meshing technique to generate finite element meshes that can adapt and move along with the transient solution behavior. A version of a nearly optimal element size determination is proposed to provide high convergence rate of the predicted solutions. The combined procedure is evaluated by solving several thermal, structural, and thermal stress problems. 相似文献
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Suthee Traivivatana Parinya BoonInartert Patcharee Theeraek Sutthisak Phongthanapanich Pramote Decha umphai 《应用数学和力学(英文版)》2007,28(9):1163-1172
A combined characteristic-based split algorithm and an adaptive meshing technique for analyzing two-dimensional viscous incompressible flow are presented.The method uses the three-node triangular element with equal-order interpolation functions for all variables of the velocity components and pressure.The main advantage of the combined method is that it improves the solution accuracy by coupling an error estima- tion procedure to an adaptive meshing technique that generates small elements in regions with a large change in solution gradients,and at the same time,larger elements in the other regions.The performance of the combined procedure is evaluated by analyzing one test case of the flow past a cylinder,for their transient and steady-state flow behaviors. 相似文献
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An explicit finite volume element method for solving characteristic level set equation on triangular grids 总被引:1,自引:0,他引:1
Level set methods are widely used for predicting evolutions of complex free surface topologies,such as the crystal and crack growth,bubbles and droplets deformation,spilling and breaking waves,and two-phase flow phenomena.This paper presents a characteristic level set equation which is derived from the two-dimensional level set equation by using the characteristic-based scheme.An explicit finite volume element method is developed to discretize the equation on triangular grids.Several examples are presented to demonstrate the performance of the proposed method for calculating interface evolutions in time.The proposed level set method is also coupled with the Navier-Stokes equations for two-phase immiscible incompressible flow analysis with surface tension.The Rayleigh-Taylor instability problem is used to test and evaluate the effectiveness of the proposed scheme. 相似文献
10.
Healing of nonphysical flow solutions and shock instability from the use of Roe's flux‐difference splitting scheme is presented. The proposed method heals nonphysical flow solutions such as the carbuncle phenomenon, the shock instability from the odd–even decoupling problem, and the expansion shock generated from the violated entropy condition. The performance and efficiency of the proposed method are evaluated by solving several benchmark and complex high‐speed compressible flow problems. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献