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Turbulence characteristics of hydraulic jumps with Froude numbers of 2.0, 2.5, and 3.32 are presented. A Micro Acoustic Doppler velocimeter was used to obtain measurements of the velocities, turbulence intensities, Reynolds stresses, and power spectra. The maximum turbulence intensities and Reynolds stress at any section were found to decrease rapidly from the toe of the jump towards downstream within the jump and then gradually level off in the transition region from the end of the jump to the friction dominated open channel flow downstream. The maximum turbulence kinetic energy at each section decreases linearly with the longitudinal distance within the jump and gradually levels off in the transition region. The Reynolds stress and turbulence intensities within the jump show some degree of similarity. The dissipative eddy size was estimated to vary from 0.04 mm within the jump to 0.15 mm at the end of the transition region. The dominant frequency is in the range from 0 to 4 Hz for both horizontal and vertical velocity components. [ABSTRACT FROM AUTHOR]

Bubble characteristics in free hydraulic jumps for inflow Froude numbers ranging from 2.0 to 6.7 were measured using a single-tip optical probe, with a focus on mean and turbulent bubble velocities. It was found that the mean bubble velocity , to a large extent, is able to reflect the water-phase flow structure in a jump. In the boundary layer of the channel bed, follows the th power law in the vertical direction, and it follows a Gaussian distribution beyond that up to the water surface. Dimensionless maximum bubble velocity was found to be smaller than that for the classical wall jet up to a characteristic distance in the longitudinal direction; beyond that, however, they agree well with each other. Turbulence intensity of bubble velocity was found to first increase and then decrease with the vertical distance from the bed. The maximum value of turbulence intensity is 33% of the inflow velocity, which is comparable to that of the water-phase. Exponential relations are proposed to describe the variation of the maximum bubble velocity and maximum turbulence intensity of bubbles, in the longitudinal direction. [ABSTRACT FROM AUTHOR]