[求助]问一个小问题:算结果与网格到底有密切的关系?

blueeye1111

如题,网格的稀疏对最后结果的影响到底有多大?是不是要把网格划分的结果差别很小时,才可以作为最后结果? 对一个边长为2米的正方形,网格分为100×100可以吗? 请赐教!谢谢

clement

[这个贴子最后由clement在 2005/05/30 09:47pm 第 1 次编辑]

这个问题值得探讨，从我看到的文章、资料来看，国内对网格划分的疏密会对计算结果有多少影响重视程度不够。特别是对紊流，如果你要得到逼近实际的计算结果，就必须注意你的网格疏密程度，从ｆｌｕｅｎｔ的帮助文件应该能得到一个感官认识：10.9 Grid Considerations for Turbulent Flow Simulations
Successful computations of turbulent flows require some consideration during the mesh generation. Since turbulence (through the spatially-varying effective viscosity) plays a dominant role in the transport of mean momentum and other scalars for the majority of complex turbulent flows, you must ascertain that turbulence quantities are properly resolved, if high accuracy is required. Due to the strong interaction of the mean flow and turbulence, the numerical results for turbulent flows tend to be more susceptible to grid dependency than those for laminar flows.
It is therefore recommended that you resolve, with sufficiently fine meshes, the regions where the mean flow changes rapidly and there are shear layers with a large mean rate of strain.
You can check the near-wall mesh by displaying or plotting the values of yplus,ystar , and Rey, which are all available in the postprocessing panels. It should be remembered that yplus,ystar , and Rey are not fixed, geometrical quantities. They are all solution-dependent. For example, when you double the mesh (thereby halving the wall distance), the new  does not necessarily become half of the  for the original mesh.
希望和大家探讨！

东岸线

如果电脑性能不跟不上 想密也密不了了

blueeye1111

我用100×100的网格和正方形四周加密得到的同一个量值不同,如平均NU数分别为80.84和113.39,到底该用哪个?难道还要继续加密,如果再得到另外不同的解,又该取哪个?我用的是湍流模型.大家说说啊?

梅花雪剑

这个问题当然存在探讨。不过偶认为：网格数量多，若加上网格质量好的，应该计算出来的结果是精确点。

yanxiaokang

原则上讲你应该继续加密,直至再加密时对你的结果已经没什么影响为止
网格的质量一定要保证