网格类型对管内旋流特性数值计算的影响

Influence of Grid Type on Numerical Calculation of Swirl Characteristics in Tubes

随着计算机技术和数值方法的高速发展,待解决科研问题的复杂程度越来越大,需要更加准确和有效地分析内部原理.高质量的网格将显著提高计算精度,如何高效地在所分析的区域生成高质量网格是计算流体动力学面临的主要困难.文章分别介绍了结构化网格和非结构化网格的生成流程(块划分,域选取),并将模拟值与经验值进行对比,误差均在10%以内.研究结果表明:以Nu作为传热评价指标,Re <600范围内非结构化网格和结构化网格均与经验数据拟合良好,两类网格的模拟值偏差不大;在Re=600~1 600范围内结构化网格的模拟值更贴近经验值;Re>1 600范围内,管内流体流动进入过渡区域,结构化网格收敛速度较非结构网格收敛速度有明显提升;结构化网格收敛速度提高1倍左右,残差值始终可以达到基本要求.

With the rapid development of computer technology and numerical methods, the complexity of scientific research problems to be solved is increasing, so it is necessary to analyze the internal principles more accurately and effectively. High quality grid will significantly improve the precision of calculation,a nd how to produce high-quality mesh efficiently in the area analyzed is the main difficulty in computational fluid dynamics. This paper introduces the generation process of structured and unstructured meshes(block division,domain selection),and compares the simulation value with the empirical value, the error is less than 10 %. The results show that Nu is used as the evaluation index of heat transfer, the unstructured meshes and structured meshes fit well with experimental data in the range of Re < 600,and the simulation values of the two types of meshes have little deviation;when Re = 600 ~ 1 600, the simulation value of structured meshes is close to the empirical values;when Re > 1 600 within the range, the fluid flow in the pipe enters the transition zone. The results show that the convergence rate of the structural grid is obviously higher than that of un-structural meshes,and the convergence rate of structured meshes is about twice as fast as that of unstructured grid,and the residual value can always meet the basic requirement.