TY - JOUR
T1 - Impact Forces of Water Drops Falling on Superhydrophobic Surfaces
AU - Zhang, Bin
AU - Sanjay, Vatsal
AU - Shi, Songlin
AU - Zhao, Yinggang
AU - Lv, Cunjing
AU - Feng, Xi-Qiao
AU - Lohse, Detlef
N1 - Funding Information:
This work received financial support from the National Natural Science Foundation of China (No. 11872227, No. 11902179, No. 11632009, No. 11921002, No. 12172189), and support from Tsinghua University (No. 53330100321). We also acknowledge funding from the ERC Advanced Grant DDD under Grant No. 740479 and from NWO via the IPP program FIP. The numerical simulations were carried out on the national -infrastructure of SURFsara, a subsidiary of SURF cooperation, the collaborative ICT organization for Dutch education and research. The authors are grateful to Marie-Jean Thoraval, Uddalok Sen, and Pierre Chantelot for the stimulating discussions. B. Z. thanks Maosheng Chai for SEM testing support.
Publisher Copyright:
© 2022 American Physical Society.
PY - 2022/9/2
Y1 - 2022/9/2
N2 - A falling liquid drop, after impact on a rigid substrate, deforms and spreads, owing to the normal reaction force. Subsequently, if the substrate is nonwetting, the drop retracts and then jumps off. As we show here, not only is the impact itself associated with a distinct peak in the temporal evolution of the normal force, but also the jump-off, which was hitherto unknown. We characterize both peaks and elucidate how they relate to the different stages of the drop impact process. The time at which the second peak appears coincides with the formation of a Worthington jet, emerging through flow focusing. Even low-velocity impacts can lead to a surprisingly high second peak in the normal force, even larger than the first one, namely when the Worthington jet becomes singular due to the collapse of an air cavity in the drop.
AB - A falling liquid drop, after impact on a rigid substrate, deforms and spreads, owing to the normal reaction force. Subsequently, if the substrate is nonwetting, the drop retracts and then jumps off. As we show here, not only is the impact itself associated with a distinct peak in the temporal evolution of the normal force, but also the jump-off, which was hitherto unknown. We characterize both peaks and elucidate how they relate to the different stages of the drop impact process. The time at which the second peak appears coincides with the formation of a Worthington jet, emerging through flow focusing. Even low-velocity impacts can lead to a surprisingly high second peak in the normal force, even larger than the first one, namely when the Worthington jet becomes singular due to the collapse of an air cavity in the drop.
U2 - 10.1103/PhysRevLett.129.104501
DO - 10.1103/PhysRevLett.129.104501
M3 - Article
SN - 0031-9007
VL - 129
JO - Physical review letters
JF - Physical review letters
IS - 10
M1 - 104501
ER -