A droplet subjected to external aerodynamic perturbations and fragmenting into smaller droplets is defined as secondary atomization. In the past decades, droplet breakup at low Ohnesorge numbers (Oh < 0.1) had been characterized with unanimity in the community regarding its physics. However, droplet breakup at high Oh number, i.e. atomization where the influence of viscosity is significant, has not been studied in detail, and there is a poor agreement in conclusions by various researchers. This work presents a thorough analysis of the modes of deformation and breakup exhibited by a high viscous (Oh = 0.5, Oh =1) droplet subjected to continuous airflow (We = 30-120). Several modes of droplet breakup are presented and transition case with no droplet fragmentation has been discovered. Size-velocity pdfs of droplets at different Ohnesorge numbers for varying Weber numbers were obtained by processing the images acquired using Digital in-line holography (DIH). Particle image velocimetry (PIV) was employed to characterize the airflow in cases where the droplets exhibited no breakup and cases with multiple bag formation. The percentage of minimum backflow velocity required for droplet breakup is also presented.

受到外部空气动力扰动并破碎成较小液滴的液滴定义为二次雾化。在过去的几十年中，低欧姆数（Oh < 0.1）下的液滴破裂在社区中被一致认为是其物理特性。然而，尚未对高Oh数下的液滴破裂（即粘度影响显着的雾化）进行详细研究，并且各种研究人员的结论不一致。这项工作全面分析了高粘性（Oh  = 0.5，Oh = 1）液滴在连续气流下的变形和破裂模式（We= 30-120）。提出了液滴分裂的几种模式，并且没有发现液滴破碎的过渡情况。通过处理使用数字在线全息照相术（DIH）采集的图像，获得了不同的Ohnesorge数以变化的Weber数的液滴尺寸-速度pdf。在液滴没有破裂或形成多个袋子的情况下，采用粒子图像测速（PIV）来表征气流。还给出了液滴破裂所需的最小回流速度的百分比。