ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

The impact of contact angle on droplet breakup dynamics in a T-junction microchannel

Zunlong Jin, Zhenghao Liu, Yong Li, Fangfang Wang, and Changliang Wang

School of Mechanical and Power Engineering, Zhengzhou University, Zhengzhou, China

E-mail: clwang@zzu.edu.cn

Received: 11 March 2025  Accepted: 17 June 2025

Abstract:

The contact angle is a critical factor influencing the droplet breakup process in microchannel systems. Through numerical simulations, this study investigates how contact angle and liquid slug length affect droplet breakup behavior in microfluidic systems. Our results reveal contact angle-dependent flow pattern transitions, particularly showing Ca-dependent modulation: With increasing Capillary numbers, the enhancing effect of hydrophilic surfaces on droplet breakup speed gradually decreases. Phase diagrams systematically mapping the (θ, Ca) parameter space elucidate breakup temporal evolution characteristics. These diagrams visually illustrate the impact of these parameters on droplet breakup, showing that good wettability promotes uniform droplet deformation and breakup while minimizing channel clogging risks. Adjusting the liquid slug length effectively controls droplet breakup speed and efficiency, particularly at contact angles above 150° and low Capillary numbers. The research identifies an optimal balance at a contact angle of 120°, where droplet breakup speed and liquid slug length are optimally balanced, maximizing daughter droplet production per unit time. Additionally, the study develops flow pattern distribution diagrams for single droplets and droplet arrays, including their transition boundaries. The study clarifies the conditions for breakup flow pattern transitions under different contact angles and proposes a fitting curve for the transition boundary, offering guidance for microfluidic device design and optimization.

Keywords: T-junction microchannel; Contact angle; Droplet breakup; Microfluidic; Droplet array

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-025-04193-3

Chemical Papers 79 (9) 6315–6332 (2025)