Abstract Numerical simulations of low-speed flow over a two-dimensional cavity at different cavity length-to-depth ratio (R) and freestream Reynolds number (Re) are performed by using the Nektar++ method. This work focuses on flow characteristics of vortices inside cavity, such as evolution process, number, and velocity due to variations in the R and Re. From the evolution process shown by the cavity flow at R = 1 and Re = 1612, it was found that both the main and corner vortices originate from the wall vortex appeared on the cavity wall, and the main vortex reaches stable faster than two corner vortices. There are seven vortices of similar size and shape arranged vertically inside the cavity for the case of R = 0.1 and Re = 1612, number of these vortices decreases to one while velocity of fluid inside the cavity increases gradually as the R increases from 0.1 to 0.9. The increase of Re results in more vortices and a larger velocity of fluid inside the cavity, furthermore, a sequence of small-scale vortical structures downstream of the cavity trailing edge are generated under the condition of Re = 25792. In addition, sidewall effects on cavity flow characteristics are investigated by employing a three-dimensional cavity, and the analysis shown that sidewall effects on flow pattern of fluid in the spanwise plane near the sidewall are not negligible.

中文翻译：

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小纵横比空腔低速流动特性数值研究

摘要 使用Nektar++方法对不同腔长深比(R)和自由流雷诺数(Re)下二维腔上的低速流动进行了数值模拟。这项工作侧重于腔内涡流的流动特性，例如由于 R 和 Re 的变化而导致的演化过程、数量和速度。从R = 1和Re = 1612时腔流的演化过程可以发现，主涡和角涡均源自腔壁上出现的壁涡，并且主涡达到稳定的速度比两个角涡快。 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? . 对于 R = 0.1 和 Re = 1612 的情况，在腔内垂直排列有七个大小和形状相似的涡流，随着 R 从 0.1 增加到 0.9，这些涡流的数量减少到 1，而腔内流体的速度逐渐增加。Re的增加导致腔内涡流增多，流体流速增大，而且在Re=25792条件下，腔后缘下游产生一系列小尺度涡结构。采用三维空腔研究空腔流动特性，分析表明侧壁对靠近侧壁的展向平面内流体流型的影响不可忽略。