Effects of viscosity on liquid structures produced by in-air microfluidics

David Baumgartner*, Günter Brenn, Carole Planchette

*Korrespondierende/r Autor/in für diese Arbeit

Publikation: Beitrag in einer FachzeitschriftArtikelBegutachtung

Abstract

This paper experimentally investigates the effect of viscosity on the outcomes of collisions between a regular stream of droplets and a continuous liquid jet. A broad variation of liquid viscosity of both the drop and the jet liquid is considered, keeping other material properties unchanged. To do so, only two liquid types were used: aqueous glycerol solutions for the drop and different types of silicone oil for the jet liquid. Combining these liquids, the viscosity ratio λ = μ_drop/μ_jet was varied between 0.25 and 3.50. The collision outcomes were classified in the form of regime maps leading to four main regimes: drops in jet, fragmented drops in jet, encapsulated drops, and mixed fragmentation.We demonstrate that, depending on the drop and jet viscosity, not all four regimes can be observed in the domain probed by our experiments. The experiments reveal that the jet viscosity mainly affects the transition between drops in jet and encapsulated drops, which is shifted towards higher drop spacing for more viscous jets. The drop viscosity leaves the previous transition unchanged but modifies the threshold of the drop fragmentation within the continuous jet. We develop a model that quantifies how the drop viscosity affects its extension, which is at first order fixing its shape during recoil and is, therefore, determining its stability against pinch-off.
Originalspracheenglisch
Aufsatznummer103602
Seitenumfang18
FachzeitschriftPhysical Review Fluids
Jahrgang5
Ausgabenummer10
DOIs
PublikationsstatusVeröffentlicht - 28 Okt 2020

Fields of Expertise

  • Advanced Materials Science

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