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PIV study of flow through porous structure using refractive index matching

Häfeli, Richard ; Altheimer, Marco ; Butscher, Denis ; Rudolf von Rohr, Philipp

In: Experiments in Fluids, 2014, vol. 55, no. 5, p. 1-13

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    Titre
    • PIV study of flow through porous structure using refractive index matching
    Auteur
    • Häfeli, Richard. Institute of Process Engineering, ETH Zürich, Sonneggstrasse 3, 8092, Zürich, Switzerland
    • Altheimer, Marco. Institute of Process Engineering, ETH Zürich, Sonneggstrasse 3, 8092, Zürich, Switzerland
    • Butscher, Denis. Institute of Process Engineering, ETH Zürich, Sonneggstrasse 3, 8092, Zürich, Switzerland
    • Rudolf von Rohr, Philipp. Institute of Process Engineering, ETH Zürich, Sonneggstrasse 3, 8092, Zürich, Switzerland
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Experiments in Fluids, 2014, vol. 55, no. 5, p. 1-13. Springer Berlin Heidelberg
    Autre version électronique
    Classification
    • Technologie, Sciences de l'ingénieur
    Identifiant OAI-PMH
    • oai:doc.rero.ch:326245
    Summary
    An aqueous solution of sodium iodide and zinc iodide is proposed as a fluid that matches the refractive index of a solid manufactured by rapid prototyping. This enabled optical measurements in single-phase flow through porous structures. Experiments were also done with an organic index-matching fluid (anisole) in porous structures of different dimensions. To compare experiments with different viscosities and dimensions, we employed Reynolds similarity to deduce the scaling laws. One of the target quantities of our investigation was the dissipation rate of turbulent kinetic energy. Different models for the dissipation rate estimation were evaluated by comparing isotropy ratios. As in many other studies also, our experiments were not capable of resolving the velocity field down to the Kolmogorov length scale, and therefore, the dissipation rate has to be considered as underestimated. This is visible in experiments of different relative resolutions. However, being near the Kolmogorov scale allows estimating a reproducible, yet underestimated spatial distribution of dissipation rate inside the porous structure. Based on these results, the $$k-\varepsilon$$ k - ε model was used to estimate the turbulent diffusivity. Comparing it to the dispersion coefficient obtained in the same porous structure, we conclude that even at $$Re_p=500$$ R e p = 500 the turbulent diffusivity makes up only a small part of mass transfer in axial direction. The main part is therefore attributed to Taylor dispersion.