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Further Comments on "Combined Forced and Free Convective Flow in a Vertical Porous Channel: The Effects of Viscous Dissipation and Pressure Work”

Magyari, E.

In: Transport in Porous Media, 2009, vol. 80, no. 2, p. 399-400

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    Title
    • Further Comments on "Combined Forced and Free Convective Flow in a Vertical Porous Channel: The Effects of Viscous Dissipation and Pressure Work”
    Author
    • Magyari, E.. Institut für Hochbautechnik, ETH Zürich, Wolfgang-Pauli Str.1, 8093, Zürich, Switzerland
    Document Type
    • Postprint
    OAI-PMH Identifier
    • oai:doc.rero.ch:318547
    Summary
    This note is concerned with the assertion of Barletta and Nield (2009a) that "a fluid with a thermal expansion coefficient greater than that of a perfect gas (β >β perfectgas) is of marginal or no interest in the framework of convection in porous media”, and that for a remark of Magyari (Transp. Porous Media, 2009) about the forced convection eigenflow solutions, the circumstance β >β perfectgas does not represent "a sound physical basis”. Here, it is shown, however, that these assertions are in contradiction with the experimentally measured values of β for important technical fluids as e.g., air, nitrogen, carbon dioxide, and ammonia where, in the temperature range between −20 and +100°C, just the inequality β >β perfectgas holds