Table 1.
Particle characteristics.
Fig 1.
Schematic description of the experimental setup, which consists of a grid turbulence tank, particle image velocimetry setup, and 2D particle tracking setup.
Dimensions on the schematic are provided in centimeters.
Fig 2.
(a) Magnified images of the 71 μm synthetic particles, (b) magnified image of the 1400 μm natural sand particle, (c) sample size distribution from the laser diffraction size analyzer for the 261 μm natural sand particles.
Table 2.
Flow characteristics.
Fig 3.
An example of time-lapse trajectories of particles with a 291 μm mean diameter at 5 Hz grid oscillations.
Fig 4.
Sample contour maps of (a) mean horizontal velocity, (b) mean vertical velocity, (c) RMS of horizontal fluctuating velocity and (d) RMS of fluctuating vertical velocity at 6 Hz grid frequency.
Fig 5.
Horizontally averaged vertical profiles of the RMS of the (a) horizontal and (b) vertical turbulent fluctuations for all grid frequencies (see legend).
Fig 6.
Auto-correlation of the vertical fluctuating velocity in the horizontal direction.
These curves allowed for the calculation of integral length scale (ℒ) as the area under this curve.
Fig 7.
Histograms of the particles’ u and v velocities in stagnant water and turbulent conditions (see subtitles) for (left) the 261 μm natural sand and (right) the 71 μm synthetic particles.
Fig 8.
Settling velocities in stagnant and turbulent flow conditions versus particle size.
The empirical curves of Dietrich [6] for particle settling velocity in stagnant water are also shown for reference.
Fig 9.
Normalized settling velocity of particles versus Stokes number based on the integral time scales.
Fig 10.
Normalized standard deviation of particle settling velocity versus Stokes number based on integral time scales.
Fig 11.
Normalized settling velocity of particles versus Stokes number based on Kolmogorov time scales.
Fig 12.
Average radius of curvature of the particles’ trajectories and corresponding POD flow pattern cell size.
The smallest cells (highest modes) represented in black and largest cells (lowest modes) represented in red. Dotted vertical lines are provided as a reference for the range of integral length scales.