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A random synthetic jet array driven turbulence tank

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Abstract

We measure the flow above an array of randomly driven, upward-facing synthetic jets used to generate turbulence beneath a free surface. Compared to grid stirred tanks (GSTs), this system offers smaller mean flows at equivalent turbulent Reynolds numbers with fewer moving parts.

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Notes

  1. We define synthetic jets in the broadest sense, such that the net mass flux, integrated over either space or time, is zero for each synthetic jet, i.e., an incurrent and excurrent port coupled via a pump or a single port that oscillates in time between incurrent and excurrent flows.

  2. Because we cannot use Taylor’s frozen field hypothesis in facilities of this nature, Re λ and Re are estimated from spatial data in PIV measurements made in a previous generation of the facility. PIV was taken in a 2 cm×2 cm plane with 0.1-mm resolution. From the velocity field in x and z, we can find the autocorrelation functions, which we then integrate to obtain L≈0.3 cm. We find ε from local gradients and by fitting to power spectra (Cowen and Monismith 1997; Liao and Cowen 2002).

  3. We find that urms is proportional to UJ; thus, Re is proportional to UJ.

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Acknowledgements

The authors gratefully acknowledge the financial support of the National Science Foundation (grant No. CTS-0093794). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. The authors wish to thank Thomas Bourdel, who built the excellent tank into which this facility was retrofitted. We also would like to acknowledge the hard work and expertise of Dr. Monroe Weber-Shirk, Lee Virtue, Paul Charles, and Jack Powers in creating this facility.

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Authors and Affiliations

  1. DeFrees Hydraulics Laboratory, School of Civil and Environmental Engineering, Cornell University, 220 Hollister Hall, Ithaca, New York, 14853, USA

    Evan A. Variano & Edwin A. Cowen

  2. Department of Physics, Cornell University, 109 Clark Hall, Ithaca, New York, 14853, USA

    Eberhard Bodenschatz

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  1. Evan A. Variano
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  2. Eberhard Bodenschatz
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  3. Edwin A. Cowen
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Correspondence to Evan A. Variano.

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Variano, E.A., Bodenschatz, E. & Cowen, E.A. A random synthetic jet array driven turbulence tank. Exp Fluids 37, 613–615 (2004). https://doi.org/10.1007/s00348-004-0833-z

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  • DOI: https://doi.org/10.1007/s00348-004-0833-z

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