Structure of wall-bounded flows at transcritical conditions

Peter C. Ma, Xiang Yang, Matthias Ihme

    Research output: Contribution to journalArticle

    4 Citations (Scopus)

    Abstract

    At transcritical conditions, the transition of a fluid from a liquidlike state to a gaslike state occurs continuously, which is associated with significant changes in fluid properties. Therefore, boiling in its conventional sense does not exist and the phase transition at transcritical conditions is known as "pseudoboiling." In this work, direct numerical simulations (DNS) of a channel flow at transcritical conditions are conducted in which the bottom and top walls are kept at temperatures below and above the pseudoboiling temperature, respectively. Over this temperature range, the density changes by a factor of 18 between both walls. Using the DNS data, the usefulness of the semilocal scaling and the Townsend attached-eddy hypothesis are examined in the context of flows at transcritical conditions - both models have received much empirical support from previous studies. It is found that while the semilocal scaling works reasonably well near the bottom cooled wall, where the fluid density changes only moderately, the same scaling has only limited success near the top wall. In addition, it is shown that the streamwise velocity structure function follows a logarithmic scaling and the streamwise energy spectrum exhibits an inverse wave-number scaling, thus providing support to the attached-eddy model at transcritical conditions.

    Original languageEnglish (US)
    Article number034609
    JournalPhysical Review Fluids
    Volume3
    Issue number3
    DOIs
    StatePublished - Mar 1 2018

    Fingerprint

    Wall flow
    Direct numerical simulation
    Scaling
    Fluids
    Fluid
    Channel flow
    Temperature
    Boiling liquids
    Phase transitions
    Channel Flow
    Structure-function
    Energy Spectrum
    Logarithmic
    Phase Transition
    Model
    Range of data

    All Science Journal Classification (ASJC) codes

    • Computational Mechanics
    • Modeling and Simulation
    • Fluid Flow and Transfer Processes

    Cite this

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    title = "Structure of wall-bounded flows at transcritical conditions",
    abstract = "At transcritical conditions, the transition of a fluid from a liquidlike state to a gaslike state occurs continuously, which is associated with significant changes in fluid properties. Therefore, boiling in its conventional sense does not exist and the phase transition at transcritical conditions is known as {"}pseudoboiling.{"} In this work, direct numerical simulations (DNS) of a channel flow at transcritical conditions are conducted in which the bottom and top walls are kept at temperatures below and above the pseudoboiling temperature, respectively. Over this temperature range, the density changes by a factor of 18 between both walls. Using the DNS data, the usefulness of the semilocal scaling and the Townsend attached-eddy hypothesis are examined in the context of flows at transcritical conditions - both models have received much empirical support from previous studies. It is found that while the semilocal scaling works reasonably well near the bottom cooled wall, where the fluid density changes only moderately, the same scaling has only limited success near the top wall. In addition, it is shown that the streamwise velocity structure function follows a logarithmic scaling and the streamwise energy spectrum exhibits an inverse wave-number scaling, thus providing support to the attached-eddy model at transcritical conditions.",
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    Structure of wall-bounded flows at transcritical conditions. / Ma, Peter C.; Yang, Xiang; Ihme, Matthias.

    In: Physical Review Fluids, Vol. 3, No. 3, 034609, 01.03.2018.

    Research output: Contribution to journalArticle

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