Journal of computational fluids engineering (한국전산유체공학회지)

Korean Society of Computational Fluids Engineering (한국전산유체공학회)
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NUMERICAL STUDY OF THE DROPLET EJECTION BEHAVIOR OF NEWTONIAN AND SHEAR-THINNING FLUIDS

뉴튼유체와 전단희석유체의 액적분사 거동에 대한 수치해석적 연구

  • Kim, E. (Dept. of Mechanical Engineering, POSTECH) ;
  • Baek, J. (Dept. of Mechanical Engineering, POSTECH)
  • 김은정 (포항공과대학교 기계공학과) ;
  • 백제현 (포항공과대학교 기계공학과)
  • Received : 2012.04.23
  • Accepted : 2012.06.26
  • Published : 2012.09.30
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Abstract

The droplet ejection behavior from drop-on-demand printhead are investigated numerically for Newtonian and shear-thinning fluid. The numerical simulation is performed using a volume-of-fluid model. In this study, we compare the printable range in terms of Z number and pinch-off time for Newtonian and shear-thinning fluids. The printability range are found to be 1.08 $$\leq_-$$ Z $$\leq_-$$ 12.9 for Newtonian fluid and 0.8 $$\leq_-$$ Z $$\leq_-$$ 12.9 for shear-thinning fluid. However, air entrainment is observed during merging of primary and satellite droplet within the printability range. The pinch-off time of the shear-thinning fluid is apparently shorter compared to the corresponding Newtonian fluid due to shear-thinning effects and the differences in the pinch-off time is enlarged significantly when the capillary number is larger than 0.5.

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References

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