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Numerical simulation of turbulent flow in an eccentric channel
European Journal of Mechanics - B/Fluids ( IF 2.6 ) Pub Date : 2020-04-27 , DOI: 10.1016/j.euromechflu.2020.04.003
Diana Sandoval Candela , Thiago Ferreira Gomes , J.N.V. Goulart , Carla Tatiana Mota Anflor

The aim of this work is to perform a numerical simulation of the turbulent flow in an eccentric channel for a Reynolds number ReDh = 7300. The Reynolds number is based on the bulk velocity, UBulk, the hydraulic-diameter, Dh, and the kinematic viscosity, ν. To achieve this goal, a hybrid RANS/LES turbulence model called DES-SST is used. In this formulation, special functions are computed to convert the model from RANS close to the walls to LES in more remote regions. Besides the Reynolds number, the main dimensionless parameter related to the geometry involves the narrow gap between the outer and inner walls of the pipes and their diameters, D and d, respectively. These geometric parameters are related to the eccentricity, e, and the d/D ratio. Both of these parameters were kept constant at 0.80 and 0.50, respectively, throughout the work, as the channel’s length, L=1500 mm. The numerical results are compared with experimental outcomes for a water channel with the same Reynolds number using PIV measurements. The hybrid scheme was able to capture the onset of gap instability, short after the channel’s inlet. Furthermore, the mass flow distribution along the channel and the flow velocity patterns were also successfully predicted by the numerical code. The Strouhal number was found to be in fair agreement with the experimental result. The large-scale structures were found to spread over the whole cross-section. The main frequency produced by the oscillatory motion in the tight gap was seen to be twice as high as that found in the lateral subchannel.



中文翻译:

偏心通道内湍流的数值模拟

这项工作的目的是对偏心通道中的雷诺数湍流进行数值模拟 回覆dH = 7300。雷诺数基于整体速度,üüķ,水力直径, dH,以及运动粘度, ν。为了实现这个目标,使用了称为DES-SST的RANS / LES混合湍流模型。在此公式中,将计算特殊功能以将模型从靠近墙壁的RANS转换为更偏远地区的LES。除雷诺数外,与几何相关的主要无量纲参数还涉及管道的内壁和内壁之间的狭窄间隙以及它们的直径Dd。这些几何参数与偏心率ed / D比有关。在整个工作过程中,随着通道的长度,这两个参数分别保持恒定在0.80和0.50。大号=1500毫米 使用PIV测量,将数值结果与具有相同雷诺数的水道的实验结果进行比较。混合方案能够在通道入口之后不久捕获间隙不稳定性的开始。此外,还可以通过数字代码成功预测沿通道的质量流量分布和流速模式。发现Strouhal数与实验结果完全吻合。发现大型结构遍布整个横截面。在狭窄的间隙中,由振荡运动产生的主频率被认为是在横向子通道中发现的主频率的两倍。

更新日期:2020-04-27
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