Experiments in Fluids

, 59:66 | Cite as

A novel method to create high density stratification with matching refractive index for optical flow investigations

Research Article

Abstract

Turbulent mixing in stratified environments represents a challenging task in experimental turbulence research, especially when large density gradients are desired. When optical measurement techniques like particle image velocimetry (PIV) are applied to stratified liquids, it is common practice to combine two aqueous solutions with different density but equal refractive index, to suppress particle image deflections. While refractive image matching (RIM) has been developed in the late 1970s, the achieved limit of 4% density ratio was not rivalled up to day. In the present work, we report a methodology, based on the behavior of excess properties and their change in a multicomponent system while mixing, that allows RIM for solutions with higher density differences. The methodology is then successfully demonstrated using a ternary combination of water, isopropanol and glycerol, for which RIM in presence of a density ratio of 8.6% has been achieved. Qualitative PIV results of a turbulent buoyant jet with 8.6% density ratio are shown.

Notes

Acknowledgements

We are indebted to colleagues at the Experimental and Computational Multiphase Flow Group of University of Michigan for many helpful discussions as well as assistance with various aspects of the experiments. The work was made possible by the generous support of DOE NEUP under Grant no 14-6552.

References

  1. Adrian RJ, Westerweel J (2011) Particle image velocimetry. Cambridge University Press, CambridgeMATHGoogle Scholar
  2. Alahyari A, Longmire EK (1994) Particle image velocimetry in a variable density flow: application to a dynamically evolving microburst. Exp Fluids 17:434–440CrossRefGoogle Scholar
  3. Anwar A, Tariq M (2007) Deviations in refractive index parameters and applicability of mixing rules in binary mixtures of benzene + 1,2-dichloroethane at different temperatures. J Chem Eng Com 195(1):43–56CrossRefGoogle Scholar
  4. Augier P, Billant P, Negretti M, Chomaz J-M (2014) Experimental study of stratified turbulence forced with columnar dipoles. Phys Fluids 26:046603CrossRefGoogle Scholar
  5. Bos WJT (2014) On the anisotropy of the turbulent passive scalar in the presence of a mean scalar gradient. J Fluid Mech 744:38–64MathSciNetCrossRefMATHGoogle Scholar
  6. Brocos P, Pinerio A, Bravo R, Amigo A (2003) Refractive indices, molar volumes and molar refractions of binary liquid mixtures: concepts and correlations. Chem Phys 5:550–557Google Scholar
  7. Daviero GJ, Roberts PJW, Maile K (2001) Refractive index matching in large-scale stratified experiments. Exp Fluids 31:119–126CrossRefGoogle Scholar
  8. Garcia B, Alcalde R, Aparicio S, Leal JM (2002) The N-methylpyrrolidone–(C1–C10) alkan-1-ols solvent systems. Phys Chem 4:1170–1177Google Scholar
  9. Hannoun IA (1985) Matching the refractive index in density stratified flows. Tech Memo 85-1, WK Keck Laboratory of Hydraulics and Water Resources, California Institute of TechnologyGoogle Scholar
  10. McDougall TJ (1979) On the elimination of refractive-index variations in turbulent density-stratified liquid flows. J Fluid Mech 93:83–96CrossRefGoogle Scholar
  11. Paladino D, Andreani M, Zboray R, Dreier J (2012) Toward CFD-grade database addressing LWR containment phenomena. Nucl Eng Dsgn 253:331–342CrossRefGoogle Scholar
  12. Petrov V, Manera A (2011). Validation of STAR-CCM+ for buoyancy driven mixing in a PWR reactor pressure vessel. In: Proc. of 14th int. topical meeting on nuclear reactor thermal-hydraulics (NURETH-14), Toronto, Canada, September 25–30Google Scholar
  13. Riley JJ, De Bruyn Kops SM (2003) Dynamics of turbulence strongly influenced by buoyancy. Phys Fluids 15:2047–2059MathSciNetCrossRefMATHGoogle Scholar
  14. Touriño A, Hervello M, Moreno V, Marino G, Iglesias M (2004) Changes of refractive indices in ternary mixtures containing chlorobenzene + n-hexane + (n-heptane or n-octane) at 298.15 K. J Serbian Chem Soc 69(6):461–475CrossRefGoogle Scholar
  15. Xiang X, Madison TJ, Sellappan P, Spedding GR (2015) The turbulent wake of a towed grid in a stratified fluid. J Fluid Mech 775:149–177MathSciNetCrossRefGoogle Scholar
  16. Yahya M, Saghir MZ (2015) Prediction and experimental measurement of refractive index in ternary hydrocarbon mixtures. J Chem Eng Data 60(8):2329–2342CrossRefGoogle Scholar

Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Department of Nuclear Engineering and Radiological SciencesUniversity of Michigan-Ann ArborAnn ArborUSA

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