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The assessment of an acoustic Doppler velocimetry profiler from a user’s perspective

Liu Da, Alobaidi Khaldoon, Valyrakis Manousos

Acta Geophysica

2022

Vol. 70, no 5

2297--2310

Acoustic Doppler velocimetry profilers (ADVPs) are widely used in both experimental and field studies because of their robustness in velocity measurements. The acquired measurements do not only offer estimates of the local and instantaneous flow velocity at the interrogated measurement volume, but can also be further processed for the estimation of the bed surface shear stresses, thus they are finding a wide range of applications ranging from water engineering to geomorphology and ecohydraulics. This study aims to evaluate the performance of an ADVP in obtaining hydrodynamics measurements under fixed flow conditions, with various probe configurations. To this goal, a robust search is conducted where ADVP probe settings are sequentially altered. A number of assessment criteria are used including qualitative observations, such as checking the shape of the velocity profile, as well as quantitative error metrics, including signal-to-noise ratio, correlations and number of spikes. Further, estimation of the bed shear stresses computed by means of using the log Law of the Wall and turbulent kinetic energy, allow obtaining a better understanding of the uncertainties involved and the importance of making a better informed choice with respect to the probe configuration settings. Thus, the methodology and performance metrics provided herein, although presented for a given flow, can generally be applied from practitioners and researchers alike.

Energy feature of a multi-flow column flotation process

Cheng G., Yu Y., Ma L., Xia W., Xu H.

Physicochemical Problems of Mineral Processing

2017

Vol. 53, iss. 2

1266--1284

A cyclonic-static micro-bubble flotation column (FCSMC) has been widely used in mineral separation. FCSMC includes countercurrent, cyclone and jet flow mineralization zones in a single column. In this study, the energy feature of the three different zones was compared. The turbulent flow was evaluated in terms of the turbulent kinetic energy (k) and the turbulent dissipation rate (ε). An appropriate computing model was determined by comparing the flow field value measured by PIV with the results of the Fluent numerical simulation. Jet flow separation exhibited the maximum k and ε values among the three columns, whereas counter-current separation displayed the minimum values. The high circulating volumetric flowrate means great energy input and turbulent intensity. The higher turbulent dissipation rate, the smaller the bubble is. The better performance of the FCSMC was mainly attributed to the multiple mineralization steps. The floatability of mineral particles gradually decreases with an increase in flotation time, the mineralization energy gradually increased to overcome the decrease in mineral floatability. By contrast, the countercurrent was beneficial for recovering the coarse particles, and the jet flow was beneficial for recovering the fine particles.