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991.
Domen Stadler Franc Kosel Damjan Čelič Andrej Lipej 《International Journal of Computational Fluid Dynamics》2013,27(8):439-448
In the article a new mesh deformation algorithm based on artificial neural networks is introduced. This method is a point-to-point method, meaning that it does not use connectivity information for calculation of the mesh deformation. Two already known point-to-point methods, based on interpolation techniques, are also presented. In contrast to the two known interpolation methods, the new method does not require a summation over all boundary nodes for one displacement calculation. The consequence of this fact is a shorter computational time of mesh deformation, which is proven by different deformation tests. The quality of the deformed meshes with all three deformation methods was also compared. Finally, the generated and the deformed three-dimensional meshes were used in the computational fluid dynamics numerical analysis of a Francis water turbine. A comparison of the analysis results was made to prove the applicability of the new method in every day computation. 相似文献
992.
Gustavo A. Ríos Rodriguez Mario A. Storti Ezequiel J. López Sofía S. Sarraf 《International Journal of Computational Fluid Dynamics》2013,27(1):31-39
Shock waves and contact discontinuities usually appear in compressible flows, requiring a fine mesh in order to achieve an acceptable accuracy of the numerical solution. The usage of a mesh adaptation strategy is convenient as uniform refinement of the whole mesh becomes prohibitive in three-dimensional (3D) problems. An unsteady h-adaptive strategy for unstructured finite element meshes is introduced. Non-conformity of the refined mesh and a bounded decrease in the geometrical quality of the elements are some features of the refinement algorithm. A 3D extension of the well-known refinement constraint for 2D meshes is used to enforce a smooth size transition among neighbour elements with different levels of refinement. A density-based gradient indicator is used to track discontinuities. The solution procedure is partially parallelised, i.e. the inviscid flow equations are solved in parallel with a finite element SUPG formulation with shock capturing terms while the adaptation of the mesh is sequentially performed. Results are presented for a spherical blast wave driven by a point-like explosion with an initial pressure jump of 105 atmospheres. The adapted solution is compared to that computed on a fixed mesh. Also, the results provided by the theory of self-similar solutions are considered for the analysis. In this particular problem, adapting the mesh to the solution accounts for approximately 4% of the total simulation time and the refinement algorithm scales almost linearly with the size of the problem. 相似文献
993.
Goal of this paper is to suitably combine a model with an anisotropic mesh adaptation
for the numerical simulation of nonlinear advection-diffusion-reaction systems and incompressible flows
in ecological and environmental applications.
Using the reduced-basis method terminology, the proposed approach leads to a noticeable computational saving of the online phase
with respect to the resolution of the reference model on nonadapted grids.
The search of a suitable adapted model/mesh pair is to be meant, instead, in an offline fashion. 相似文献
994.
In this paper, a new method of topological cleanup for quadrilateral mesh is presented. The method first selects a patch of mesh around an irregular node. It then seeks the best connection of the selected patch according to its irregular valence using a new topological operation: small polygon reconnection (SPR). By replacing the original patch with an optimal one that has less irregular valence, mesh quality can be improved. Three applications based on the proposed approach are enumerated: (1) improving the quality of a quadrilateral mesh, (2) converting a triangular mesh to a quadrilateral one, and (3) adapting a triangle generator to a quadrilateral one. The presented method is highly effective in all three applications. 相似文献
995.
On the Fully Implicit Solution of a Phase-Field Model for Binary Alloy Solidification in Three Dimensions
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Christopher E. Goodyer Peter K. Jimack rew M. Mullis Hongbiao Dong & Yu Xie 《advances in applied mathematics and mechanics.》2012,4(6):665-684
A fully implicit numerical method, based upon a combination of
adaptively refined hierarchical meshes and geometric multigrid, is
presented for the simulation of binary alloy solidification in
three space dimensions. The computational techniques are presented for a
particular mathematical model, based upon the phase-field approach,
however, their applicability is of greater generality than for the
specific phase-field model used here. In particular, an implicit
second order time discretization is combined with the use of second order
spatial differences to yield a large nonlinear system of algebraic
equations as each time step. It is demonstrated that these equations
may be solved reliably and efficiently through the use of a nonlinear
multigrid scheme for locally refined grids. In effect, this paper
presents an extension of earlier research in two space
dimensions (J. Comput. Phys., 225 (2007), pp. 1271-1287) to fully
three-dimensional problems. This extension is validated against earlier
two-dimensional results and against some of the limited results
available in three dimensions, obtained using an explicit scheme.
The efficiency of the implicit approach and the multigrid solver are
then demonstrated and some sample computational results for the
simulation of the growth of dendrite structures are presented. 相似文献
996.
Yang—Yang thermodynamics of one-dimensional Bose gases with anisotropic transversal confinement
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By combining the thermodynamic Bethe ansatz and local density approximation, we investigate the Yang—Yang thermodynamics of interacting one-dimensional Bose gases with anisotropic transversal confinement. It is shown that with the increase of anisotropic parameter at low temperature, the Bose atoms are distributed over a wider region, while at high temperature the density distribution is not affected obviously. Both the temperature and transversal confinement can strengthen the local pressure of the Bose gases. 相似文献
997.
998.
The lattice Boltzmann method (LBM) for two-phase flow simulation is often hindered by insufficient resolution at the interface. As a result, the LBM simulation of bubbles in bubbling flows is commonly limited to spherical or slightly deformed bubble shapes. In this study, the adaptive mesh refinement method for the LBM is developed to overcome such a problem. The approach for this new method is based on the improved interaction potential model, which is able to maintain grid-independent fluid properties in the two-fluid phases and at the interface. The LBM–AMR algorithm is described, especially concerning the LBM operation on a non-uniform mesh and the improved interaction potential model. Numerical simulations have been performed to validate the method in both single phase and multiphase flows. The 2D and 3D simulations of the buoyant rise of bubbles are conducted under various conditions. The agreement between the simulated bubble shape and velocity with experiments illustrates the capability of the LBM–AMR approach in predicting bubble dynamics even under the large bubble deformation conditions. Further, the LBM–AMR technique is capable of simulating a complex topology change of the interface. Integration of LBM with AMR can significantly improve the accuracy and reduce computation cost. The method developed in this study may appreciably enhance the capability of LBM in the simulation of complex multiphase flows under realistic conditions. 相似文献
999.
1000.
横观各向同性超弹性球壳的有限振动 总被引:4,自引:0,他引:4
应用有限变形动力学理论研究了一种横观各向同性不可压超弹性材料球壳在表面突加均布拉伸载荷作用下的有限振动问题.给出了球壳振动的振幅和外加载荷之间的关系,得到了,球壳振动的相同和近似的周期,讨论了球壳振动的振幅、相图及振动的周期和材料各向异性程度的关系. 相似文献