• Betteridge, K. F. E., , Bell P. S. , , Thorne P. D. , , and Williams J. J. , 2006: Evaluation of a triple-axis coherent Doppler velocity profiler for measuring near-bed flow: A field study. J. Atmos. Oceanic Technol., 23 , 90106.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Blanckaert, K., , and De Vriend H. J. , 2004: Secondary flow in sharp open-channel bends. J. Fluid Mech., 498 , 353380.

  • Blanckaert, K., , and Lemmin U. , 2006: Means of noise reduction in acoustic turbulence measurements. J. Hydraul. Res., 44 , 137.

  • Bouvard, M., , and Dumas H. , 1967: Application de la méthode de fil chaud à la mesure de la turbulence dans l’eau (in French). La Houille Blanche, 22 , 257278.

    • Search Google Scholar
    • Export Citation
  • Brumley, B. H., , and Jirka G. H. , 1987: Near-surface turbulence in a grid-stirred tank. J. Fluid Mech., 183 , 235263.

  • Davies, A. G., , and Thorne P. D. , 2005: Modeling and measurement of sediment transport by waves in the vortex ripple regime. J. Geophys. Res., 110 .C05017, doi:10.1029/2004JC002468.

    • Search Google Scholar
    • Export Citation
  • De Silva, I. P. D., , and Fernando H. J. S. , 1992: Some aspects of mixing in a stratified turbulent patch. J. Fluid Mech., 240 , 601625.

  • Elgar, S., , Raubenheimer B. , , and Guza R. T. , 2005: Quality control of acoustic Doppler velocimeter data in the surfzone. Meas. Sci. Technol., 16 , 18891893.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Garbini, J. L., , Forster F. K. , , and Jorgensen J. E. , 1982: Measurement of fluid turbulence based on pulsed ultrasound techniques. Part I: Analysis. J. Fluid Mech., 118 , 445470.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Gratiot, N., , Michallet H. , , and Mory M. , 2005: On the determination of the settling flux of cohesive sediments in a turbulent fluid. J. Geophys. Res., 110 .C06004, doi:10.1029/2004JC002732.

    • Search Google Scholar
    • Export Citation
  • Hay, A. E., , and Sheng J. , 1992: Vertical profiles of suspended sand concentration and size from multifrequency acoustic backscatter. J. Geophys. Res., 97 , 1566115677.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hoefel, F., , and Elgar S. , 2003: Wave-induced sediment transport and sandbar migration. Science, 299 , 18851887.

  • Hopfinger, E. J., , and Toly J. A. , 1976: Spatially decaying turbulence and its relation to mixing across density interfaces. J. Fluid Mech., 78 , 155175.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hurther, D., , and Lemmin U. , 1998: A constant-beam-width transducer for 3D acoustic Doppler profile measurements in open-channel flows. Meas. Sci. Technol., 9 , 17061714.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hurther, D., , and Lemmin U. , 2000: Shear stress statistics and wall similarity analysis in turbulent boundary layers using a high resolution 3D ADVP. IEEE J. Oceanic Eng., 25 , 446457.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hurther, D., , and Lemmin U. , 2001: A correction method for mean turbulence measurements with a 3D acoustic Doppler velocity profile. J. Atmos. Oceanic Technol., 18 , 446458.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hurther, D., , and Lemmin U. , 2003: Turbulent particle flux and momentum flux statistics in suspension flow. Water Resour. Res., 39 .1139, doi:10.1029/2001WR001113.

    • Search Google Scholar
    • Export Citation
  • Hurther, D., , Michallet H. , , and Gondran X. , 2007: Turbulent measurements in the surf zone suspension. J. Coastal Res., SI50 , 297301.

  • Kim, S-C., , Friedrichs C. T. , , Maa J. P-Y. , , and Wright L. D. , 2000: Estimating bottom stress in a tidal boundary layer from acoustic Doppler velocimeter data. J. Hydraul. Eng., 126 , 399406.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lane, S. N., and Coauthors, 1998: Three-dimensional measurement of river channel flow processes using acoustic Doppler velocimetry. Earth Surf. Processes Landforms, 23 , 12471267.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lhermitte, R., , and Lemmin U. , 1994: Open-channel flow and turbulence measurement by high-resolution Doppler sonar. J. Atmos. Oceanic Technol., 11 , 12951308.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • López, F., , and Garcia M. H. , 1999: Wall similarity in turbulent open-channel flow. J. Eng. Mech., 125 , 789796.

  • Loupas, T., , and Gill R. W. , 1994: Making full use of the information present in the backscattered RF echoes. IEEE Trans. Ultrason. Ferroelectr. Freq. Control, 41 , 522531.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Matsunaga, N., , Sugihara Y. , , Komatsu T. , , and Masuda A. , 1999: Quantitative properties of oscillating-grid turbulence in a homogeneous fluid. Fluid Dyn. Res., 25 , 147165.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Nezu, I., , and Nakagawa H. , 1993: Turbulence in Open-Channel Flows. A. A. Balkema, 281 pp.

  • Nikora, V. I., , and Goring D. G. , 2000: Flow turbulence over fixed and weakly mobile gravel beds. J. Hydraul. Eng., 126 , 679690.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rotta, J. C., 1972: Turbulente Strömungen, eine Einführung in die Theorie und ihre Anwendungen. B. G. Teubner, 267 pp.

  • Rouse, H., , and Dodu J. , 1955: Diffusion turbulente à travers une discontinuité de densité. Houille Blanche, 10 , 522532.

  • Sénéchal, N., , Bonneton P. , , and Dupuis H. , 2002: Field experiment on secondary wave generation on a barred beach and the consequent evolution of energy dissipation on the beach face. Coastal Eng., 46 , 233247.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Thompson, S. M., , and Turner J. , 1975: Mixing across an interface due to turbulence generated by an oscillating grid. J. Fluid Mech., 67 , 349368.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Thorne, P. D., , and Hanes D. M. , 2001: A review of acoustic measurement of small-scale sediment processes. Cont. Shelf Res., 22 , 603632.

    • Search Google Scholar
    • Export Citation
  • Trowbridge, J., , and Elgar S. , 2001: Measurements of surfzone turbulence. J. Phys. Oceanogr., 31 , 24032417.

  • Turner, J., 1968: The influence of molecular diffusivity on turbulent entrainment across a density interface. J. Fluid Mech., 33 , 639656.

  • Ura, M., , Komatsu T. , , and Matsunaga N. , 1987: Entrainment due to oscillating-grid turbulence in two-layered fluid. Turbulence Measurements and Flow Modeling, C. J. Chen, L. D. Chen, and F. M. Holly Jr., Eds., Hemisphere Publishing, 109–118.

    • Search Google Scholar
    • Export Citation
  • Voulgaris, G., , and Trowbridge J. H. , 1998: Evaluation of the Acoustic Doppler Velocimeter (ADV) for turbulence measurements. J. Atmos. Oceanic Technol., 15 , 272289.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Zappa, C. J., , Raymond P. A. , , Terray E. A. , , and McGillis W. R. , 2003: Variation in surface turbulence and the gas transfer velocity over a tidal cycle in a macro-tidal estuary. Estuaries, 26 , 14011415.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Zedel, L., , Hay A. E. , , Cabrera R. , , and Lohrmann A. , 1996: Performance of a single-beam pulse-to-pulse coherent Doppler profiler. IEEE J. Oceanic Eng., 21 , 290297.

    • Crossref
    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 40 40 2
PDF Downloads 22 22 0

Improved Turbulence Profiling with Field-Adapted Acoustic Doppler Velocimeters Using a Bifrequency Doppler Noise Suppression Method

View More View Less
  • 1 Laboratoire des Ecoulements Géophysiques et Industriels, CNRS UMR 5519, Grenoble, France
  • | 2 Laboratoire d’Hydraulique Environnementale, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
© Get Permissions
Restricted access

Abstract

A novel noise reduction method and corresponding technique are presented for improving turbulence measurements with acoustic Doppler velocimeters (ADVs) commonly used in field studies of coastal and nearshore regions, rivers, lakes, and estuaries. This bifrequency method is based on the decorrelation of the random and statistically independent Doppler noise terms contained in the Doppler signals at two frequencies. It is shown through experiments in an oscillating grid turbulence (OGT) tank producing diffusive isotropic turbulence that a shift in carrier frequency of less than 10% is sufficient to increase the resolved frequency range by a decade in the turbulent velocity spectra. Over this spectral range, the slope of the velocity spectra agrees well with the universal inertial range value of −5/3. The limit due to spatial averaging effects over the sample volume can be determined from the abrupt deviation of the spectral slope from the −5/3 value. As a result, the relative error of the turbulent intensity estimate and the turbulent kinetic energy (TKE) dissipation rate, measured by two different methods, does not exceed 10% in the case of isotropic turbulence. Furthermore, the bifrequency method allows accurate estimates of the turbulent microscales as shown by the good agreement of the ratio between the Taylor and Kolmogorov microscales and an Re1/4t power law. Compared to previous Doppler noise reduction methods (Garbini et al.), an increase in time resolution by a factor of 4 is achieved. The proposed method also avoids the loss of TKE energy contained in isotropic flow structures of size equal to and smaller than the sample volume. Different from Doppler noise methods proposed by Hurther and Lemmin and Blanckaert and Lemmin, this method does not require additional hardware components, electronic circuitry, or sensors because the redundant instantaneous velocity field information is captured with the same transducer. The required shift in carrier frequency is small enough for the bifrequency method to be easily implemented in commercial ADVs.

Corresponding author address: D. Hurther, Laboratoire des Ecoulements Géophysiques et Industriels, CNRS UMR 5519, Grenoble, France. Email: david.hurther@hmg.inpg.fr

Abstract

A novel noise reduction method and corresponding technique are presented for improving turbulence measurements with acoustic Doppler velocimeters (ADVs) commonly used in field studies of coastal and nearshore regions, rivers, lakes, and estuaries. This bifrequency method is based on the decorrelation of the random and statistically independent Doppler noise terms contained in the Doppler signals at two frequencies. It is shown through experiments in an oscillating grid turbulence (OGT) tank producing diffusive isotropic turbulence that a shift in carrier frequency of less than 10% is sufficient to increase the resolved frequency range by a decade in the turbulent velocity spectra. Over this spectral range, the slope of the velocity spectra agrees well with the universal inertial range value of −5/3. The limit due to spatial averaging effects over the sample volume can be determined from the abrupt deviation of the spectral slope from the −5/3 value. As a result, the relative error of the turbulent intensity estimate and the turbulent kinetic energy (TKE) dissipation rate, measured by two different methods, does not exceed 10% in the case of isotropic turbulence. Furthermore, the bifrequency method allows accurate estimates of the turbulent microscales as shown by the good agreement of the ratio between the Taylor and Kolmogorov microscales and an Re1/4t power law. Compared to previous Doppler noise reduction methods (Garbini et al.), an increase in time resolution by a factor of 4 is achieved. The proposed method also avoids the loss of TKE energy contained in isotropic flow structures of size equal to and smaller than the sample volume. Different from Doppler noise methods proposed by Hurther and Lemmin and Blanckaert and Lemmin, this method does not require additional hardware components, electronic circuitry, or sensors because the redundant instantaneous velocity field information is captured with the same transducer. The required shift in carrier frequency is small enough for the bifrequency method to be easily implemented in commercial ADVs.

Corresponding author address: D. Hurther, Laboratoire des Ecoulements Géophysiques et Industriels, CNRS UMR 5519, Grenoble, France. Email: david.hurther@hmg.inpg.fr

Save