The spillways are one of the most important hydraulic structures used in river engineering, dam construction, irrigation, and drainage engineering projects. Recently, a new type of such spillways with a circular crest has been proposed. In this paper, the hydraulic properties of the circular crested stepped spillway (CCSS) including flow pattern, distribution of velocity on the crest and pressure, turbulence intensity, discharge coefficient (\({C}_{d}\)) and energy dissipation ratio (EDR) were investigated numerically. To model the free surface of flow the volume of fluid technique, and for modeling the turbulence of flow, k − ε (RNG) was utilized. Results declared that there is a good agreement between the laboratory observations and numerical simulation. The \({C}_{d}\) of the CCSS changes between 0.9 and 1.4 considering the range of relative upstream head (\({h}_{up}/R\)) between 0.33 m and 2.67. The observation of the flow streamlines showed that they are tangential to the curvature of the crest and there is no separation of the flow from the crest. Examination of the pressure distribution on the CCSS model shows that just downstream part of the crest, the pressure is partially negative. Of course, the same partial negative pressure is observed on the edge of the steps. The steps increase the maximum intensity turbulence by 50%. The CCSS can dissipate the energy of flow between 90 and 30%, and in the skimming flow regime, the portion of each step in the energy dissipation regardless of their position is almost identical.

溢洪道是河流工程、大坝建设、排灌工程中最重要的水工建筑物之一。最近，有人提出了一种新型的这种带有圆形顶部的溢洪道。本文研究了圆顶阶梯溢洪道（CCSS）的水力特性，包括流型、顶面速度分布和压力分布、湍流强度、流量系数（\({C}_{d}\)）和能量耗散。对比率（EDR）进行了数值研究。为了模拟流动的自由表面，流体体积技术，以及为了模拟流动的湍流，使用了 k - ε (RNG)。结果表明，实验室观察和数值模拟之间存在良好的一致性。\ ( {C}_{d}\)考虑到相对上游水头 ( \({h}_{up}/R\) ) 在 0.33 m 和 2.67 之间的范围，CCSS 的 0.9 和 1.4 之间变化。对流动流线的观察表明，它们与波峰的曲率相切，并且流动与波峰没有分离。对 CCSS 模型上的压力分布的检查表明，就在波峰的下游部分，压力是部分负的。当然，在台阶边缘也观察到相同的局部负压。这些台阶将最大强度湍流增加了 50%。CCSS 可以耗散 90% 到 30% 的流动能量，并且在撇取流状态下，无论其位置如何，每一步的能量耗散部分几乎相同。