Abstract The efficacy of reconstructing three-dimensional (3D) volumes of time-evolving three-component velocity from planar experimental measurements is explored within strong shear-distorting turbulent flows using Taylor’s frozen turbulence hypothesis. In flows with a strong mean shear-rate the instantaneous turbulence structure is spuriously distorted with the classical Taylor’s hypothesis method, where the local ensemble average velocity is used as the convective velocity to reconstruct 3D volumes. In the current study, two additional models for the convective velocity that extend the classical Taylor’s hypothesis approach are explored with varied levels of mean shear-rate and turbulence intensity in order to reconstruct 4D velocity fields for time-resolved analysis of turbulence structure. The classical Taylor’s frozen turbulence hypothesis is compared with local time average and instantaneous convective velocities, with and without a Poisson solver step to maintain continuity. Direct numerical simulation data of a turbulent channel flow from the Johns Hopkins Turbulence Database are used to assess the accuracy of the three methods while varying mean shear-rate and turbulence intensity independently. The three methods are also applied to time-resolved sPIV measurements on transverse planes within the near-wall surface layer of a canonical flat-plate turbulent boundary layer to assess the statistical means of the reconstructions. The instantaneous convective velocity method is generally found to be most accurate at reconstructing instantaneous velocity fields, although systematic biases are observed in mean statistics. In flows with lower turbulence intensities, the local time average convective velocity is comparable for significantly lower computation and implementation costs.
Sheppard et al. (Wed,) studied this question.