The establishment of an internal flowfield inside a single water droplet subjected to shock-wave impact is numerically and theoretically investigated. The main focus is on the description of the droplet internal flow pattern, which is believed to be one of the dominant factors in initial droplet deformation. The droplet internal flow pattern holds steady for quite a long time after the incident shock passage, and a saddle point is observed for the first time. Accordingly, the saddle point inside the droplet flow is used as a characteristic point to describe the internal flow. Cases of different incident shock strengths are tested, and a theoretical prediction is proposed to delineate the correlation between the saddle point steady position and the strength of the incident shock wave. The numerical cases are found to be in good agreement with the prediction. The present study helps to complete the understanding of the overall droplet aerobreakup phenomenon.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This research was supported by projects of the Research Grants Council of Hong Kong, under contracts CRF C5010-14E and GRF 152151/16E, and of the Natural Science Foundation of China, number 11372265. The authors are very grateful to anonymous referees for the time spent reading and analyzing the manuscript. The many insightful remarks helped the authors improve the quality of the paper.