Dispensing of rheologically complex fluids at the dripping regime

Hyejin Han, Chongyoup Kim

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)


Dispensing characteristics of rheologically complex fluids are investigated experimentally at the dripping regime. Two mixtures of ethylene glycol and glycerin (50:50 and 31:69) were used as base Newtonian fluids. As the polymer solution, 1000. ppm of polyacrylamide of 5-6M. g/mol was added to the 50:50 base Newtonian fluid. 2.5, 5 or 7.5. vol% of polystyrene particles of 2. μm in diameter were added to the liquids to prepare particle suspensions. The liquids were dispensed to the air by using a nozzle with the inner and outer diameters of 0.61 and 0.91. mm, respectively. It was found that the drop size is primarily determined by the balance of drop weight and surface tension force holding the drop, and hence drop size does not depend on volume flow rate. The drop diameter is approximately 10% smaller for elastic liquids due to the severe extension of the filament before the detachment from the nozzle. The result also shows that the dripping characteristics of the fluids without the polymer are mainly determined by the balance of the gravity force, surface tension force holding the liquid volume and pressure force. The addition of less than approximately 10% of 2. μm spherical particles hardly changes the dispensing characteristics of Newtonian fluids except at the final stage of detachment. For polymeric liquids, the transient extensional property drastically changes the dripping dynamics. The force balance shows that the strain hardening of the polyacrylamide solution under the extensional flow causes severe retardation of the filament breakup. The filament breakup of the polymeric suspension is further decelerated by the increase in zero shear viscosity as a result of the particle addition.

Original languageEnglish
Pages (from-to)57-67
Number of pages11
JournalJournal of Non-Newtonian Fluid Mechanics
Publication statusPublished - 2014 Nov 1

Bibliographical note

Funding Information:
This work was partially supported by Mid-career Researcher Program through NRF grant funded by the MEST ( Ministry of Education, Science and Technology ), Korea (No. 2010-0015186 ).

Publisher Copyright:
© 2014 Elsevier B.V.


  • Dripping mechanism
  • Drop size
  • Filament breakup
  • Strain hardening
  • Transient elongational viscosity

ASJC Scopus subject areas

  • General Chemical Engineering
  • General Materials Science
  • Condensed Matter Physics
  • Mechanical Engineering
  • Applied Mathematics


Dive into the research topics of 'Dispensing of rheologically complex fluids at the dripping regime'. Together they form a unique fingerprint.

Cite this