This paper illustrates recent progresses in the development of the smoothed particle hydrodynamics (SPH) method to simulate and post-process liquid spray generation. The simulation of a generic annular airblast atomizer is presented, in which a liquid sheet is fragmented by two concentric counter swirling air streams. The accent is put on how the SPH method can bridge the gap between the CAD geometry of a nozzle and its characterization, in terms of spray characteristics and dynamics. In addition, the Lagrangian nature of the SPH method allows to extract additional data to give further insight in the spraying process. First, the sequential breakup events can be tracked from one large liquid blob to very fine stable droplets. This is herein called the tree of fragmentation. From this tree of fragmentation, abstract quantities can be drawn such as the breakup activity and the fragmentation spectrum. Second, the Lagrangian coherent structures in the turbulent flow can be determined easily with the finite-time Lyapunov exponent (FTLE). The extraction of the FTLE is particularly feasible in the SPH framework. Finally, it is pointed out that there is no universal and ultimate non-dimensional number that can characterize airblast primary breakup. Depending on the field of interest, a non-dimensional number (e.g. Weber number) might be more appropriate than another one (e.g. momentum flux ratio) to characterize the regime, and vice versa.

中文翻译：

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用平滑粒子流体动力学方法模拟和后处理环形喷气雾化器数值模拟的进展

本文阐述了平滑粒子流体动力学 (SPH) 方法在模拟和后处理液体喷雾生成方面的最新进展。介绍了通用环形鼓风雾化器的模拟，其中液体片被两个同心反向旋转气流破碎。重点在于 SPH 方法如何弥合喷嘴的 CAD 几何形状与其在喷雾特性和动力学方面的特性之间的差距。此外，SPH 方法的拉格朗日性质允许提取额外的数据，以进一步了解喷涂过程。首先，可以跟踪从一个大的液体斑点到非常细的稳定液滴的连续破裂事件。这在本文中称为碎片树。从这棵分裂之树，可以绘制抽象数量，例如破碎活动和碎裂谱。其次，湍流中的拉格朗日相干结构可以很容易地用有限时间李雅普诺夫指数 (FTLE) 确定。FTLE 的提取在 SPH 框架中特别可行。最后指出，没有一个通用的和最终的无量纲数可以表征喷气一次破裂。根据感兴趣的领域，无量纲数（例如韦伯数）可能比另一个数（例如动量通量比）更适合表征该状态，反之亦然。FTLE 的提取在 SPH 框架中特别可行。最后指出，没有一个通用的、终极的无量纲数可以表征喷气一次破裂。根据感兴趣的领域，无量纲数（例如韦伯数）可能比另一个数（例如动量通量比）更适合表征该状态，反之亦然。FTLE 的提取在 SPH 框架中特别可行。最后指出，没有一个通用的、终极的无量纲数可以表征喷气一次破裂。根据感兴趣的领域，无量纲数（例如韦伯数）可能比另一个数（例如动量通量比）更适合表征该状态，反之亦然。