Highly Resolved LES and URANS of Turbulent Buoyancy-Driven Flow Within Inclined Differentially-Heated Enclosures
Highly Resolved LES and URANS of Turbulent Buoyancy-Driven Flow Within Inclined Differentially-Heated Enclosures
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DOI：
10.1007/s10494-013-9497-1
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发表时间：
2013-10-01
影响因子：
2.4
通讯作者：
Iacovides, Hector
中科院分区：
文献类型：
--
作者：
Ammour, Dalila;Craft, Tim;Iacovides, Hector
在本研究中，LES和非定常RANS计算，在差热矩形倾斜空腔内使用有限体积代码（Code_Saturne）的空气湍流自然对流，纵横比H/L = 28.6和瑞利数为0.86x10（6）。注意力集中在两个倾斜角度上：15 A度到水平，具有热的下壁和冷的上壁，15 A度不稳定的情况，以及该情况的镜像，其中角度相同但具有热的上壁和冷的下壁，15 A度稳定的情况。根据最近的实验数据，LES计算的稳定和不稳定的倾斜空腔返回三维时间平均流场。在不稳定分层封闭体的情况下，流动是高度不稳定的，在封闭体的核心中具有相干湍流结构。LES计算得到的时间平均温度、速度和湍流强度与实测数据吻合较好。随后使用不同的URANS方案与LES的比较，以探讨在何种程度上这些模型能够再现大规模的非定常流结构。所有的URANS格式都能再现15 A度不稳定空腔中的三维非定常流动特征。然而，所测试的低雷诺数模型，以及需要一个高分辨率的近壁网格，也需要一个更精细的网格在核心区域比高雷诺数模型，从而使其计算非常昂贵。15 A度稳定空腔内的流动也显示出一些三维特征，尽管它的不稳定性明显降低，并且这里测试的URANS模型在再现这种流型方面不太成功。这里给出了两种不同加热外壳的总传热。
In the present study, both LES and unsteady RANS computations are presented, for turbulent natural convection of air inside differentially-heated rectangular tilted cavities using a finite volume code (Code_Saturne), for an aspect ratio of H/L = 28.6 and Rayleigh number of 0.86x10(6). Attention is focused on two angles of inclination: 15A degrees to the horizontal with hot lower and cold upper wall, the 15A degrees unstable case, and the mirror image of this case where the angle is the same but with a hot upper and cold lower wall, the 15A degrees stable case. In accordance with recent experimental data, the LES computations for both the stable and unstable tilted cavities returned three-dimensional time-averaged flow fields. In the case of the unstably stratified enclosure, the flow is highly unsteady with coherent turbulent structures in the core of the enclosure. Time-averaged temperature, velocity and resolved turbulence intensities resulting from LES computations show close agreement to measured data. Subsequent comparisons of different URANS schemes with LES are used in order to explore to what extent these models are able to reproduce the large-scale unsteady flow structures. All URANS schemes have been found to be able to reproduce the 3-D unsteady flow features present in the 15A degrees unstable cavity. However, the low-Reynolds-number model tested, as well as requiring a high resolution near-wall grid, also needed a finer grid in the core region than the high-Reynolds-number models, thus making it computationally very expensive. Flow within the 15A degrees stable cavity also shows some 3-D features, although it is significantly less unsteady, and the URANS models tested here have been less successful in reproducing this flow pattern. The overall heat transfer is presented here for both differentially heated enclosures.