Although being a common situation for fish and underwater vehicles, limited research has been reported for a fish-like body swimming in oblique incoming flows. The present work employs the immersed boundary-lattice Boltzmann method to numerically study the dynamics of this problem. A more comprehensive analysis method, which utilizes the effective force parameters that consolidate the angle of attack (AOA) into the traditional force parameters, is proposed for investigating the dynamics of cases with non-zero AOA. Several distinct features in terms of the dynamic performance, the periodic features, and the flow field characteristics are presented. For the dynamic performance, undulation amplitude plays a more dominant role than the undulation form in thrust generation. The periodic features revealed by the Fourier spectra present increasing complexity with larger AOA. Besides, three flow regimes are identified, one of which observes hierarchical vortex structures with different orders in time and space. The small-scale vortex street generated by undulation is “local” in both time and space, and it is embedded in the large scale vortex street generated by the body and the free-stream.

尽管对于鱼和水下航行器来说是一种普遍情况，但对于斜向流入的类似鱼的身体游泳的报道很少。目前的工作采用沉浸边界格子玻尔兹曼方法来数值研究该问题的动力学。提出了一种更全面的分析方法，该方法利用将攻角（AOA）合并为传统力参数的有效力参数来研究非零AOA案件的动力学。在动态性能，周期性特征和流场特性方面，提出了几个不同的特征。对于动态性能，在推力产生中起伏幅度比起伏形式起更主要的作用。傅里叶光谱揭示的周期性特征随着较大的AOA呈现出越来越大的复杂性。此外，确定了三种流动状态，其中一种观察了在时间和空间上具有不同顺序的分层涡结构。由起伏产生的小规模涡流街在时间和空间上都是“局部”的，并且嵌入在由身体和自由流产生的大型涡流街中。