Evaluation of turbulence budget terms and the spectra using highly resolved hot and cold wire measurements over a desert playa

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Thursday, 6 February 2014: 1:45 PM
Room C206 (The Georgia World Congress Center )
Vigneshwaran Kulandaivelu, University of Utah, Salt Lake City, UT; and D. D. Jenson, S. Hoch, and E. R. Pardyjak

Direct measurements of production and dissipation rate terms in the turbulent kinetic energy budget and the temperature variance budget were made using hot-wire anemometry. The measurements of the velocity and temperature fluctuations were obtained using two co-located x-wire and cold wire probes at different heights ranging from 2cm to 50cm. Both the x-wires and the cold wires consisted of 5 micrometer Tungsten wire that was approximately 1mm in length. These high fidelity temperature and turbulence data were acquired during the MATERHORN experimental campaign at the SLTEST facility of the US Army Dugway Proving Grounds in Utah's West Desert. The rate of turbulent kinetic energy dissipation term was calculated using the third order structure function, whereas the sensible heat flux in the buoyancy production term was calculated directly from the covariance of the vertical velocity and temperature fluctuations. The spectra for both temperature and velocity fluctuations are computed to demonstrate the capability and the limitations of the experimental technique. The one dimensional spectra of the temperature and streamwise velocity fluctuations are computed in Kolmogorov normalized form. The velocity spectra seem to show -5/3 slope in the dissipative region of the spectra. The one dimensional Kolmogorov spectral constant estimated from these data set was about 0.5 and the scalar spectral constant was about 0.8 (in agreement with the literature).