论文标题
在统一气流中的液滴胶片分解
Bag Film Breakup of Droplets in Uniform Airflows
论文作者
论文摘要
我们提出了新的数值模拟，研究了液滴的袋子破裂。与理论和实验相比，我们首先研究了袋式破裂开始之前对滴剂变形的粘性作用。接下来，在很晚的时间形成袋子膜，容易受到数值模拟中虚假网格诱导的分裂的影响，这阻止了先前的研究达到片段统计的网格收敛。因此，我们采用了多种死亡（MD）算法，该算法一旦薄膜达到了独立于网格大小的临界厚度，就可以人为地穿孔，并由数值参数$ l _ {\ rm sig} $控制。我们在使用MD算法时显示了碎片统计数据的网格收敛，并分析碎片行为和袋子膜瓦解机制，包括韧带破裂，节点脱离和边缘不稳定。我们选择的临界厚度参数$ l _ {\ rm sig} $受数值约束的限制，因此与实验或理论不匹配。因此，当前的模拟产生的关键袋膜穿孔厚度大于实验观察到的。 MD算法配置对袋子分手现象和统计数据的影响将在未来的工作中进行研究。我们还研究了中等液体Ohnesorge编号（$ 0.005 \ leq OH \ leq 0.05 $）对袋子分解过程和碎片统计的影响，其中发现了袋装片段平均直径对$ OH $的非单调依赖性。这些结果突出了MD算法在涉及拓扑变化的多相模拟中的实用性，并为基于物理学的数值研究铺平了对空气接口处的烟草产生的道路。
We present novel numerical simulations investigating the bag breakup of liquid droplets. We first examine the viscous effect on drop deformation before the onset of bag breakup, comparing with theory and experiment. Next, a bag film forms at late time and is susceptible to spurious mesh-induced breakup in numerical simulations, which has prevented previous studies from reaching grid convergence of fragment statistics. We therefore adopt the manifold death (MD) algorithm which artificially perforates thin films once they reach a prescribed critical thickness independent of the grid size, controlled by a numerical parameter $L_{\rm sig}$. We show grid convergence of fragment statistics when utilising the MD algorithm, and analyse the fragment behaviour and bag film disintegration mechanisms including ligament breakup, node detachment and rim destabilisation. Our choice of the critical thickness parameter $L_{\rm sig}$ is limited by numerical constraints and thus has not been matched to experiment or theory; consequently, the current simulations yield critical bag film perforation thicknesses larger than experimentally observed. The influence of the MD algorithm configuration on the bag breakup phenomena and statistics will be investigated in future work. We also study the effects of moderate liquid Ohnesorge number ($0.005 \leq Oh \leq 0.05$) on the bag breakup process and fragment statistics, where a non-monotonic dependency of the average diameter of bag film fragments on $Oh$ is found. These results highlight the utility of the MD algorithm in multiphase simulations involving topological changes, and pave the way for physics-based numerical investigations into spume generation at the air-sea interface.
