The influence of system scale on impinging jet sediment erosion: Observed using novel and standard measurement techniques

Hunter, Timothy N.; Peakall, Jeff; Unsworth, Thomas J.; Acun, Mehmet Hakan; Keevil, Gareth M.; Rice, Hugh P.; Biggs, Simon

doi:10.1016/j.cherd.2013.02.002

Cited by 17 publications

(9 citation statements)

References 40 publications

(68 reference statements)

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“…The current authors have previously undertaken similar analysis alongside phenomenological approaches to characterise concentrated, settling and turbulent dispersions of large glass beads, plastic particles and colloidal minerals in pipe flows, as well as small and large industrial scale tanks [26][27][28][29][30][31][32]. Collectively, this research provides pathways to enable online characterisation of many concentrated dispersion systems in industries ranging from cosmetic, pharmaceutical, food and paint products, to water treatment, minerals and nuclear waste processing.…”

Section: Introductionmentioning

confidence: 95%

Measurement and density normalisation of acoustic attenuation and backscattering constants of arbitrary suspensions within the Rayleigh scattering regime

et al. 2019

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The scattering and attenuation of megahertz frequency acoustic backscatter in liquid suspensions, is examined for a range of fine organic and inorganic particles in the Rayleigh regime, 10 -4 < ka < 10 0 (where k is the wavenumber and a the particle radius) which are widely industrially relevant, but with limited existing data. In particular, colloidal latex, mineral titania and barytes sediments, as well as larger glass powders were investigated. A manipulation of the backscatter voltage equation was used to directly measure the sediment attenuation constants, . Decoupling of the combined backscattering-transducer constant, allowing explicit measurement of the backscattering constant, ks, was achieved through calibration of the transducer constant, kt. Additionally, the methodology was streamlined via averaging between a number of intermediate concentrations to reduce data variability. This approach enabled the form function, f, and the corresponding total normalized scattering cross-sections, , to be determined for all species. While f and are available in the literature for large glass and sand, this methodology allowed extension for the colloidal organic and inorganic particles. Specific gravity normalisation of f collapsed all data onto a single distribution, with the exception of titania, due to scattering complexities associated withagglomeration. There was some additional variation in , with measured values of the fine particles up to of magnitude greater than the density-normalised prediction at low ka . Mechanisms accounting for these variations from theory are however analysed, and include viscous attenuation effects, the polydispersity of the particle type and increasing influence of the solvent attenuation.Additionally, thermoacoustic losses appeared to dominate the attenuation behaviour of the organic latex particles. This study demonstrates that particles close to the colloidal regime can be measured successfully with acoustic backscatter, and highlights the great potential of this technique to be applied for in situ or online monitoring purposes in such systems.

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Section: Introductionmentioning

confidence: 95%

Measurement and density normalisation of acoustic attenuation and backscattering constants of arbitrary suspensions within the Rayleigh scattering regime

et al. 2019

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“…7 Among them one of the most used is the "jet erosion test" 8 that consists in measuring the eroded mass and depth from the crater generated by the action of a water jet impacting the soil. Such a configuration presents some strong facilities from a practical point of view, e.g., a simple use in the field, but also some difficulties of interpretation, 9,10 even for a cohesionless soil where erosion is considered as a simple particle problem. These difficulties to interpret the results of the jet erosion test mainly arise from the strong non-uniform flow with a stagnation point at the bottom of the jet axis.…”

Section: Introductionmentioning

confidence: 99%

Erosion threshold of a liquid immersed granular bed by an impinging plane liquid jet

2014

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Erosion threshold of a model granular bed by a jet in a quasi bidimensional configuration has been studied experimentally in both laminar and turbulent regimes. The jet is a liquid sheet which impinges normally a packing of immersed beads monodisperse in size and density. The erosion threshold has been characterized at different impact distances of the jet on the sediment and for different grain size and fluid viscosity. In the explored range of parameters, we show that the erosion threshold is well described by a critical inertial Shields number based on the local flow velocity at the impinging point. This has been done by a careful analysis of the different jet flow regimes taking into account the position of the virtual origin of the jet.

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“…We validate the theory using INTRODUCTION There are multiple practical situations addressed in the fields of hydrology, geomorphology, and planetary science which concern a jet plunging into a pool of water with a bottom constituted by a cohesionless granular material, and deal with the associated scour of such beds (Graf and Altinakar 1998). These situations include common potholes which occur downstream of hydraulic structures (Graf and Altinakar 1998), lead to crevasse lakes (USGS), are driven by head-cuts in drainage network evolution (Stein et al 1993), form on consolidated deposits of nuclear waste (Hunter et al 2013), take part during cleansing of gravel bars (Minh 1989), and were created on Mars during Amazonian times (Wilson et al 2004). Under those conditions, a turbulent cauldron initially appears within the pool of water; this cauldron then grows as it scours the pothole.…”

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Temporal evolution of jet induced scour depth in cohesionless granular beds and the phenomenological theory of turbulence

2018

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In this work, we investigate the temporal evolution of the jet-driven scour depth in a pothole lying on a cohesionless granular bed, by using diverse approaches. First, we present new experiments which encompass cases with jet angles ranging from 45 to 90° from the horizontal, several initial water depths, and different particle sizes, supplementing experiments developed recently by the last two authors. In particular, we address relatively-large angles, mostly absent in previous analyses. Our results first confirm the existence of two very different stages in the scour process, essentially overlooked in datasets used to obtain the traditional formulas-developing and developed phases; they then provide unprecedented evidence of the very distinct behavior at 90°, characterized by a step-wise behavior. Second, after revisiting the rationale of a theory our new, and other datasets. Finally, we provide interesting interpretations of the scour process by using the results of the theory.

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The influence of system scale on impinging jet sediment erosion: Observed using novel and standard measurement techniques

Cited by 17 publications

References 40 publications

Measurement and density normalisation of acoustic attenuation and backscattering constants of arbitrary suspensions within the Rayleigh scattering regime

Measurement and density normalisation of acoustic attenuation and backscattering constants of arbitrary suspensions within the Rayleigh scattering regime

Erosion threshold of a liquid immersed granular bed by an impinging plane liquid jet

Temporal evolution of jet induced scour depth in cohesionless granular beds and the phenomenological theory of turbulence

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