Droplet Impact on Surfaces with Asymmetric Microscopic FeaturesShow others and affiliations
2021 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 37, no 36, p. 10849-10858Article in journal (Refereed) Published
Abstract [en]
The impact of liquid drops on a rigid surface is central in cleaning, cooling, and coating processes in both nature and industrial applications. However, it is not clear how details of pores, roughness, and texture on the solid surface influence the initial stages of the impact dynamics. Here, we experimentally study drops impacting at low velocities onto surfaces textured with asymmetric (tilted) ridges. We found that the difference between impact velocity and the capillary speed on a solid surface is a key factor of spreading asymmetry, where the capillary speed is determined by the friction at a moving three-phase contact line. The line-friction capillary number Caf = μfV0/σ (where μf,V0, and σ are the line friction, impact velocity, and surface tension, respectively) is defined as a measure of the importance of the topology of surface textures for the dynamics of droplet impact. We show that when Caf ≪ 1, the droplet impact is asymmetric; the contact line speed in the direction against the inclination of the ridges is set by line friction, whereas in the direction with inclination, the contact line is pinned at acute corners of the ridges. When Caf ≫ 1, the geometric details of nonsmooth surfaces play little role.
Place, publisher, year, edition, pages
American Chemical Society (ACS), 2021. Vol. 37, no 36, p. 10849-10858
National Category
Physical Chemistry
Identifiers
URN: urn:nbn:se:sh:diva-46339DOI: 10.1021/acs.langmuir.1c01813ISI: 000697110000021PubMedID: 34469168Scopus ID: 2-s2.0-85115030147OAI: oai:DiVA.org:sh-46339DiVA, id: diva2:1591791
Funder
Swedish Research Council, 2015-04019Swedish Foundation for Strategic Research , SSF-FFL62021-09-072021-09-072021-10-08Bibliographically approved