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Wave breaking and wave runup/rundown have a major influence on nearshore hydrodynamics, morphodynamics and beach evolution. In the case of wave breaking, there is significant mixing of air and water at the wave crest, along with relatively high kinetic energy, so prediction of the free surface is complicated. Most hydrodynamic studies of surf and swash zone are derived from single-phase flow, in which the role of air is ignored. Two-phase flow modeling, consisting of both phases of water and air, may be a good alternative numerical modeling approach for simulating nearshore hydrodynamics and, consequently, sediment transport. A two-phase flow tool can compute more realistically the shape of the free surface, while the effects of air are accounted for. This paper used models based on two-dimensional, two-phase Reynolds-averaged Navier–Stokes equations, the volume-of-fluid surface capturing technique and different turbulence closure models, i.e., k–ε, k–ω and re-normalized group (RNG). Our numerical results were compared with the available experimental data. Comparison of the employed method with a model not utilizing a two-phase flow modeling demonstrates that including the air phase leads to improvement in simulation of wave characteristics, especially in the vicinity of the breaking point. The numerical results revealed that the RNG turbulence model yielded better predictions of nearshore zone hydrodynamics, although the k–ε model also gave satisfactory predictions. The model provides new insights for the wave, turbulence and means flow structure in the surf and swash zones. 相似文献
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Several two-equation turbulence models using isotropic eddy viscosity and wall functions are assessed by solution of the neutral atmospheric boundary layer over a flat surface and wind flow over two- and three-dimensional models and real terrain. Calculations are presented for wind flow over the Sirhowy Valley in Wales, an embankment along the Rhine in Germany and the Askervein Hill in Scotland. Comparisons of predictions with previous work, and laboratory and field data, show that the RNG-based k– model gives the best agreement with respect to the flow profiles and length of the separated flow region. The results of this model are analyzed with a non-linear stress-strain relation to gauge the potential effect of turbulence anisotropy. 相似文献
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应用基于RNG方法的湍流模型数值模拟钝体绕流的湍流流动 总被引：27，自引：2，他引：25
首次采用基于RNG方法的湍流模型对绕流钝体后尾流流场进行了数值模拟。计算在任意非正交曲线坐标系下,采用非交错网格的有限体积法求解二维不可压N-S方程,计算结果与实验数据以及与采用标准的κ-ε两方程湍流模型计算的结果进行比较,结果表明基于RNG方法的湍流模型对于与时间相关的大尺度运动——旋涡脱落的尾流的详细结构,能够给出真实的模拟。 相似文献
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低扬程双向流道泵站是我国独创的泵站型式,为深入了解其流道内流场特性,首次运用基于壁面律的RNG κ-ε的湍流模型对流道进行数值模拟。计算采用交错网格的有限体积法求解三维不可压Navier Stokes方程。提出优化出水流道的目标函数,并依据数值模拟结果,预测出水流道水力损失。根据经验公式计算的水力损失和预测的出水流道水力损失两者较为接近,表明通过采用基于壁面律的RNG湍流模型能较好地预测出水流道的水力性能。考虑壁面律的RNG湍流模型在泵站流道内特性数值模拟和外特性预测研究方面有较好的推广价值。 相似文献
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