Kelvin–Helmholtz instability in an ultrathin air film causes drop splashing on smooth surfaces
Tóm tắt
Liquid drops always splash when they impact smooth surfaces with high enough speeds. This common phenomenon is crucial in many important fields such as agriculture, printing, surface coating, and spray cooling. However, despite extensive studies over one century, the origin of splashing remains a big mystery. Combining experiment with model, we show that the air trapped under the liquid drop forms a special flow within a nanoscale gap. This airflow produces a stress 10 times stronger than the common airflow and generates small Kelvin–Helmholtz instabilities that trigger splash. Our model agrees quantitatively with the experimental verifications and brings a fundamental understanding to the general phenomenon of drop splashing on smooth surfaces.
Từ khóa
Tài liệu tham khảo
AM Worthington, On the forms assumed by drops of liquids falling vertically on a horizontal plate. Proc R Soc Lond 25, 261–272 (1876).
H Lamb Hydrodynamics (Dover, 6th Ed, New York, 1945).