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Outline
CFD simulations of flow past a circular cylinder at subcritical Reynolds numbers pose several challenges, including the accurate prediction of shear-layer Kelvin-Helmholtz (K-H) instabilities, low-frequency unsteady behavior, and the formation mechanisms of V-shaped and U-shaped wake velocity profiles. In this study, a novel wall-modeled hybrid turbulence model, termed TNT WM-XLES, is developed by reconstructing the turbulent kinetic energy (k) equation of the Transitional k–ω Turbulence (TNT) model, thereby significantly enhancing the resolution of turbulent kinetic energy within the shear layer. Numerical validations demonstrate that the proposed model not only accurately reproduces the first- and second-order wake statistics, but also successfully captures three characteristic spectral features: the high-frequency peak associated with shear-layer K–H instability, the dominant peak corresponding to vortex shedding, and the low-frequency peak related to recirculation-zone oscillations. By introducing the instantaneous recirculation-zone length parameter, Lr(t), a quantitative consistency is observed between its dominant spectral frequency and the low-frequency signal. This finding establishes, for the first time, a direct link between the low-frequency instability of cylinder wake flows and the periodic contraction–expansion dynamics of the recirculation zone through a dynamic characteristic parameter. The proposed model overcomes the limitations of conventional RANS/LES approaches in capturing low-frequency flow features and provides an effective and practical tool for high-fidelity simulations of complex bluff-body flows in engineering applications.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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