Oceanic vortex merging is an important physical process for the vortex evolution and its impact on marine environment. However, limitation of the in-situ oceanic observational data of vortex merging inhabits its better understanding. This study investigates the interactions between non-ideal vortices in a four-vortex flow field in a rotating tank. We examine the merging stages of anticyclonic vortices, influenced by two other cyclonic vortices and their respective dynamical behaviors and quantify the effects of merging on vortex characteristics. The results indicate a strong shear flow between two counter-rotating vortices, which accelerates the motion of the anticyclonic vortex, while cyclonic ones exhibit greater stability. Subsequently, different stages of non-ideal vortex merging in a co-rotating framework are defined, primarily the encircling stage, rapid approaching stage, and merging vortex stage. In addition, we quantify and compare variations in morphological parameters and anti-symmetric vorticity distribution of non-ideal vortices across these stages. The stretching of vortices primarily occurs along the line connecting their centers due to the strain field exerted by neighboring vortices, resulting in an asymmetric stretching pattern in the interactions among non-ideal vortices. Furthermore, during the merging process, non-ideal vortices disperse vorticity outward and accumulate vortex filaments in the surrounding environment, leading to distinctive variations in anti-symmetric vorticity distribution, affecting their respective merging efficiency.

中文翻译：

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旋转罐实验室实验中涡合并的分析

海洋涡合并是涡演化及其对海洋环境影响的重要物理过程。然而，涡合并现场海洋观测数据的局限性阻碍了对其更好的理解。本研究研究了旋转槽内四涡流场中非理想涡流之间的相互作用。我们研究了反气旋涡旋的合并阶段，受其他两个气旋涡旋及其各自的动力学行为的影响，并量化了合并对涡旋特性的影响。结果表明，两个反向旋转涡旋之间存在强烈的剪切流，这加速了反气旋涡旋的运动，而气旋涡旋则表现出更大的稳定性。随后，定义了同转框架中非理想涡合并的不同阶段，主要是环绕阶段、快速接近阶段和合并涡阶段。此外，我们还量化并比较了这些阶段的非理想涡流的形态参数和反对称涡度分布的变化。由于相邻涡流施加的应变场，涡流的拉伸主要发生在连接其中心的线上，导致非理想涡流之间的相互作用产生不对称的拉伸模式。此外，在合并过程中，非理想涡会向外分散涡量，并在周围环境中积累涡丝，导致反对称涡度分布的明显变化，影响各自的合并效率。