Computational fluid dynamics (CFD) method was used to numerically simulate the two-phase flow on stepped spillways to investigate the initiation mechanism of self-aeration in stepped spillways and clarify the impact of step length on the self-aeration characteristics of stepped spillways with non-uniform step lengths, including concave, convex, random, and semi-uniform step length configurations. Compared with the traditional uniform steps scheme, the results show that both concave and convex configurations prove unsuitable for rapid initiation of self-aeration, leading to a 6.4% and 7.0% posterior shift in the aeration inception points. Although random step configuration promotes the development of turbulent boundary layers to some extent, the inherent uncertainty in their step length arrangements induces excessive surface fluctuations. The semi-uniform step scheme can significantly move forward the position of the initial aeration point (by 18.8%) while ensuring a relatively stable flow state, which has a broader application prospect.
| 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 |