Author(s): Zhou Jianyin; Shao Xuejun; Yang Yan; Qin Cuicui; Jia Dongdong

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Keywords: Consecutive reverse bends; Numerical modeling; Circulation; Turbulent model

Abstract: Consecutive reverse bends with and without a connecting section were simulated by RANS with SA, SKE (standard k-ε) and NKE (nonlinear k-ε) turbulent models respectively in this work. Numerical results were compared with experimental measured data in details. Discrepancies had been carefully analyzed. Experimental data indicate that, if the connecting section is long enough, the impact of upper bend to lower bend would be so small that both bends could be regarded as a single bend. In such case, simulations of RANS with different turbulent models show little difference, while all of them successfully simulate the flow field except the small outer-bank secondary circulation and its impact on the longitudinal velocity profile. For consecutive reverse bends without connecting section, the circulation goes more complex downstream, and the accuracy of numerical modeling goes worse. RANS with either turbulent model can predict the new circulation emerges near the bottom in the lower bend, but fail to simulate its detailed characteristics. The comparison conclude that NKE and SKE can perform muchbetter than SA turbulent model in complex circulation circumstances, and NKE shows a little better than SKE.

DOI:

Year: 2013