• Title/Summary/Keyword: Capillary spreading of droplet

Search Result 3, Processing Time 0.016 seconds

DEVELOPMENT OF A NUMERICAL TECHNIQUE FOR CAPILLARY SPREADING OF A DROPLET CONTAINING PARTICLES ON THE SOLID SUBSTRATE (미세입자분산 액적의 고체면에서 모세퍼짐 현상에 관한 직접수치해석 기법개발)

  • Hwang, Wook-Ryol;Jeong, Hyun-Jun;Kim, See-Jo;Kim, Chong-Youp
    • Journal of computational fluids engineering
    • /
    • v.12 no.4
    • /
    • pp.14-19
    • /
    • 2007
  • We present a direct numerical simulation technique and some preliminary results of the capillary spreading of a droplet containing particles on the solid substrate. We used the level-set method with the continuous surface stress for description of droplet spreading with interfacial tension and employed the discontinuous Galerkin method for the stabilization of the interface advection equation. The distributed Lagrangian-multipliers method has been combined for the implicit treatment of rigid particles. We investigated the droplet spreading by the capillary force and discussed effects of the presence of particles on the spreading behavior. It has been observed that a particulate drop spreads less than the pure liquid drop. The amount of spread of a particulate drop has been found smaller than that of the liquid with effectively the same viscosity as the particulate drop.

Spreading and retraction dynamics of a liquid droplet impacting rough hydrophobic surfaces: Formation of micrometer-sized drops (거친 발수 표면에 충돌하는 유체 방울의 팽창 및 수축 역학: 미세 유체 방울의 형성)

  • Kim, Uijin;Kim, Jeong-Hyun
    • Journal of the Korean Society of Visualization
    • /
    • v.19 no.3
    • /
    • pp.15-21
    • /
    • 2021
  • In this study, we investigated the dynamics of a droplet impacting rough hydrophobic surfaces through high-speed imaging. Micrometer-sized structures with grooves and pillars were fabricated on smooth Polydimethylsiloxane (PDMS) surfaces by laser ablation. We used Newtonian and non-Newtonian liquid droplets to study the drop impact dynamics. De-ionized water and aqueous glycerin solutions were used for the Newtonian liquid droplet. The solutions of xanthan gum in water were prepared to provide elastic property to the Newtonian droplet. We found that the orientation of the surface structures affected the maximal spreading diameter of the droplet due to the degree of slippage. During the droplet retraction, the dynamic receding contact angles were measured to be around 90° or less. It resulted in the formation of the micro-capillary bridges between the receding droplet and the surface structures. Then, the rupture of the capillary bridge led to the formation of micrometer-sized droplets on top of the surface structures. The size of the microdroplets was found to increase with increasing the impacting velocity and viscosity of the Newtonian liquid droplets. However, the size of the isolated microdroplets decreased with enhancing the elasticity of the droplets, and the size of the non-Newtonian microdroplets was not affected by the impacting velocity.

A Visualization Study of Liquid Spreading on Micro/nano Textured Surfaces with Synchrotron X-ray Imaging (방사광 X-선 영상법을 활용한 마이크로/나노 구조 표면에서의 액체 퍼짐 가시화 연구)

  • Kwak, Ho Jae;Yu, Dong In;Doh, Seungwoo;Park, Hyun Sun;Kim, Moo Hwan
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.41 no.8
    • /
    • pp.531-536
    • /
    • 2017
  • Nano/micro technology is currently applied to improve solid surface wettability, with recent research studies indicating that nanostructures can improve surface wettability in the hydrophilic direction, and liquid spreading (propagation) is generated by capillary wicking. The majority of the existing research involves qualitative analysis of the spreading phenomena, owing to the difficulty in conducting small-scale analysis (nanostructures). In this study, the droplet interfacial behavior on silicon surfaces with micro/nano/micro-nano structures is experimentally investigated. The interfacial behavior is directly visualized using synchrotron X-ray imaging (side view). The spreading phenomena occur on structured surfaces, and the liquid interface behaviors on the surfaces differ. The liquid film thickness is uniform during spreading on the microstructured surface, but not on the nano case which shows a gentle slope. These combined spreading shapes were observed on a micro-nano structured surface, and liquid propagation was enhanced when the micro- and nano-structures are combined.