Spreading behaviors of shear-thinning droplets impacting on solid surfaces with various wettability

• Published in: Korea-Australia rheology journal Vol. 36; no. 3; pp. 155 - 167
• Main Authors: Yang, Ding, Chen, Jiaqi, Shen, Ao, Wang, Junfeng, Liu, Hailong
• Format: Journal Article
• Language: English
• Published: Seoul / Melbourne Korean Society of Rheology, Australian Society of Rheology 01.08.2024; Springer Nature B.V; 한국유변학회
• Subjects: Behavior; Characterization and Evaluation of Materials; Chemistry and Materials Science; Complex Fluids and Microfluidics; Droplets; Evolution; Food Science; Hydrophobic surfaces; Hydrophobicity; Impact velocity; Materials Science; Mechanical Engineering; Original Article; Polymer Sciences; Rescaling; Shear; Shear thinning (liquids); Soft and Granular Matter; Solid surfaces; Viscosity; Wettability; Xanthan; 공학일반; Maximum spreading; Droplet impact; Surface wettability; Shear-thinning fluid
• ISSN: 1226-119X; 2093-7660
• DOI: 10.1007/s13367-024-00098-x

The spreading behavior of droplets impacting solid surfaces is of significant importance in numerous industrial and medical applications. This study specifically focuses on the droplet impact behaviors of shear-thinning fluids. Extensive impact experiments were conducted using high-speed visualization techniques. Image sequences in the DI water and xanthan gum solution droplets impact process are captured at a We range of around 3.2–388 and Re n of 18–8145. The morphologies of spreading droplets on hydrophilic, moderate, and hydrophobic surfaces was observed with temporal evolution. The experimental results showed that the spreading behavior of shear-thinning droplets varies with the impact velocity, surface wettability, and fluid concentration. The droplets spread more widely and rapidly at larger We with the time evolution of the spreading factor. In addition, the spreading of the droplets becomes suppressed on a hydrophobic surface or with a higher xanthan concentration. With the increase of We , the effect of fluid viscosity gradually surpasses the surface wettability. The fluid viscosity with the shear-thinning properties has more influence on the spreading behavior at high We . Furthermore, the experimental data of the maximum spreading factor could be scaled with the We and Re n at low and high We , respectively. Finally, the maximum spreading of shear-thinning droplets was correlated with a universal rescaling model. The correlation shows good accordance with the experimental results of droplet impact from this study and the literature in a wide range of impact conditions and shear-thinning properties. Graphical abstract