圆柱绕流的三大类型湍流模型及稳定性数值模拟研究

The three types of turbulence models and stability numerical simulation studies for cylindrical flow

  • 摘要: 海港桩基码头下方桩柱周围的绕流特性对港口水动力与泥沙输运具有重大影响。为探究湍流数值模拟方法对三维桩柱绕流精度的影响,基于CFD方法建立OpenFOAM湍流模型,在雷诺数Re=3 900条件下,研究不同近壁取值范围y+=0.95~5.00内的大涡模拟LES、原始雷诺时均法(RANS)湍流模型和增加涡流黏度限制公式的RANS湍流模型的阻力系数、斯特劳哈尔数、平均压力系数、平均速度和涡流结构。研究结果表明,与前人RANS各湍流模型及试验计算结果比较,RNG κ-ε湍流模型对阻力系数和斯特劳哈尔数模拟较准确,对涡捕捉精细程度最好;κ-ω、κ-ω SST湍流模型对斯特劳哈尔数模拟较准确,在y+=0.95~2.00时对平均压力系数模拟较准确;各RANS湍流模型对平均速度的模拟均存在回流区内速度偏差较大的问题;大涡模拟LES湍流模型在近壁网格精度较高时,所有水动力模拟结果相对准确。研究还发现增加涡流黏度限制后的RANS湍流模型,对涡结构捕捉的精细程度更高,更符合真实流动。通过对不同湍流模型下单桩水动力特性的分析研究,可为海港码头下圆形桩群的水动力计算提供参考。

     

    Abstract: The characteristics of flow around pile columns beneath harbor pile-wharf docks significantly influence port hydrodynamics and sediment transport. To explore the impact of turbulent numerical simulation methods on the precision of three-dimensional pile flow, an OpenFOAM turbulence model based on the CFD method was developed. Under the condition of Reynolds number Re=3,900, this study investigates the drag coefficient, Strouhal number, mean pressure coefficient, mean velocity, and vortex structure in different near-wall value ranges y+=0.95~5.00 for Large Eddy Simulation (LES), the original Reynolds-averaged Navier-Stokes (RANS) turbulence model, and the RANS turbulence model with added eddy viscosity limitation formula. Results indicate that compared with previous RANS turbulence models and experimental results, the RNG κ-ε turbulence model simulates the drag coefficient and Strouhal number more accurately and captures vortices with the greatest finesse; κ-ω and κ-ω SST turbulence models simulate the Strouhal number accurately and simulate the mean pressure coefficient accurately within y+=0.95~2.00. All RANS turbulence models exhibit significant backward flow velocity deviations in mean velocity simulations; the LES turbulence model, at higher near-wall grid precision, provides relatively accurate hydrodynamic simulation results. Moreover, the RANS turbulence model, with added eddy viscosity limitations, captures vortex structures with greater finesse, aligning more closely with real flow behavior. Analyzing and researching the hydrodynamic characteristics of single piles under different turbulence models can provide references for hydrodynamic calculations of circular pile groups beneath harbor docks.

     

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