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Scaling criteria for high Reynolds and Peclet number turbulent flow, scalar transport, mixing, and heat transfer

Zhou, Y (LLNL)
Friday 03 October 2008, 14:00-14:30

Seminar Room 1, Newton Institute


Very high Reynolds (Re) and Peclet (Pe) number turbulent flows are commonly encountered in engineering, geophysical and astrophysical applications. In comprehensive statistical flow experiments or corresponding direct numerical simulations of high Re and Pe number turbulent flow, scalar transport, mixing, and heat transfer the energetic excitation influences of the entire range of dynamic spatial scales combining both velocity fluctuations and passive scalar variances must be considered together. However, direct computational simulations or experiments directed to the very high Re and Pe flows of practical interest commonly exceed the resolution possible using current or even foreseeable future super computer capability or spatial, temporal and diagnostic technique limitations of current laboratory facilities. Pragmatic considerations and practical needs promote use of statistical flow data bases developed from direct numerical simulations or experiments at the highest Re and Pe levels achievable within the currently available facility limitations. Unfortunately the obtainable levels are lower than those associated with the flows of practical interest. Moreover, at present, there is no metric to indicate whether and how much of the fully resolved physics of the flow of interest has been captured within the facilities available to the investigator. This talk presents metric criteria based on establishing a smaller subset of the total range of dynamic scale interactions that will still faithfully reproduce all of the essential, theoretically significant, influences of the complete range of scale interactions associated with the flows of practical interest. The present work leads to the identification of the minimum significant Re flow and Pe field that a researcher must attain in direct simulation or experiment (hereafter called the minimum state). These threshold criteria levels are minimum values to be attained in experiments or direct simulations which assure that the energy-containing scales of the flows ? and scalar fields under investigation are not contaminated by the (non-universal) velocity dissipation and scalar diffusivity inertial range scale limits.


[ppt ]


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