Flow around a high-rise building using steady and unsteady RANS CFD: Effect of large-scale fluctuations on the velocity statistics
Flow around a high-rise building using steady and unsteady RANS CFD: Effect of large-scale fluctuations on the velocity statistics
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DOI：
10.1016/j.jweia.2015.03.013
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发表时间：
2015-07-01
影响因子：
4.8
通讯作者：
Tominaga, Yoshihide
中科院分区：
文献类型：
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作者：
Tominaga, Yoshihide
在这项研究中，非定常的雷诺平均Navier-Stokes（URANS）湍流模拟的性能周围的高层建筑的1：1：2形状的流场进行了检查。采用k-ω剪切应力输运（SST）模型，通过URANS计算成功地再现了建筑物后的非定常波动。其他湍流模型，即标准k-ε模型、重整化群理论（RNG）k-ε模型、可实现k-ε模型和标准k-ω模型，都无法实现这种再现。使用k-ω SST模型的URANS计算成功地再现了建筑物周围的大规模非定常流型的某个部分，并且与定常RANS计算相比，能够更准确地预测建筑物后面的速度分布。然而，URANS计算高估了建筑物拐角处的气流分离。在RNG k-ε模型中引入了一个修正的ε方程，使其能够再现周期性波动，更准确地预测建筑物屋顶的气流分离。该修正考虑了平均流周期性对大尺度脉动与小尺度湍流之间能量传递的影响。总的来说，使用RNG k-ESTA模型与修改后的ε方程的URANS计算的结果表现出最好的协议与实验结果。(C)2015爱思唯尔有限公司版权所有。
In this study, the performance of the unsteady Reynolds-averaged Navier-Stokes (URANS) turbulence modeling of the flow field around a high-rise building with a 1:1:2 shape was examined. The unsteady fluctuation behind the building was successfully reproduced by URANS computation using the k-omega shear stress transport (SST) model. This reproduction could not be achieved by other turbulence models, namely, the standard k-epsilon, renormalization group theory (RNG) k-epsilon, realizable k-epsilon, and standard k-omega models. The URANS computation using the k-omega SST model successfully contributed to the reproduction of a certain part of the large-scale unsteady flow patterns around the building, and enabled more accurate prediction of the velocity distributions behind the building compared to the steady-RANS computation. However, the URANS computation overestimated the flow separation at the building corners. A modified epsilon-equation was introduced into the RNG k-epsilon model to enable its use to reproduce the periodic fluctuation and more accurately predict the flow separation on the roof of the building. The modification took into consideration the effects of the mean-flow periodicity on the energy transfer between large-scale fluctuations and small-scale turbulence. Overall, the results of the URANS computation using the RNG k-epsilon model with the modified epsilon-equation exhibited the best agreement with experimental results. (C) 2015 Elsevier Ltd. All rights reserved.