Determination of the critical Shields number for particle erosion in laminar flow

Ouriemi, Malika; Aussillous, Pascale; Médale, Marc; Peysson, Yannick; Guazzelli, Élisabeth

doi:10.1063/1.2747677

Cited by 93 publications

(142 citation statements)

References 11 publications

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“…We remark that the critical Shields numbers detected in our study and also in that by Charru et al 20 are considerably lower than those around 0.12 provided by Ouriemi et al, 17 Charru et al 20 and Derksen 19 for the onset of particle motion in irregularly arranged granular beds. In view of our results, this can be understood due to the strong dependence of the critical Shields number on the burial degree as well as on the angle between flow and substrate orientation.…”

Section: Discussioncontrasting

confidence: 50%

“…Fluids 24, 093302 (2012) this phenomenon as bed armouring, which yields an increase of the threshold for particle motion. 16 Independent from the particle Reynolds number, Ouriemi et al 17 observed in their experimental study a constant critical Shields number for incipient motion of about 0.12 in laminar flow at about the same value as Charru et al 16 for a saturated compact bed. Studying a single particle on an irregularly arranged bed of identical particles, Charru et al observed an influence of the local substrate geometry on the onset of particle motion and the traveling trajectory.…”

Section: Introductionmentioning

confidence: 85%

“…27 Including laminar flow conditions, the scatter of data in literature is supposed to be due to different criteria for onset of motion concept. 17 In the present article, we consider the displacement of the particle to a neighboring equilibrium position on the substrate as the threshold condition. We characterize the incipient motion by the critical Shields number, which compares the characteristic shear stress acting on the particle to the resistant specific particle weight that retains it in place.…”

Section: Resultsmentioning

confidence: 99%

“…9 Others studied directly the onset of motion of granular beds, focused on the grain size-dependent transport of fine particles in turbulent open channel flow. [10][11][12][13] While some authors focused the sediment transportation induced by turbulent flows, 14,15 Charru et al, 16 Ouriemi et al, 17 Lobkovsky et al, 18 and Derksen, 19 studied the onset of particle motion in laminar shear flows using an irregularly arranged granular bed. Charru et al observed an increase of the compactness of the granular bed due to the local arrangement of the particles and characterized a) Author to whom correspondence should be addressed.…”

Section: Introductionmentioning

confidence: 99%

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Incipient motion of a single particle on regular substrates in laminar shear flow

Agudo

Wierschem

2012

Physics of Fluids

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We study experimentally the critical conditions for incipient motion of a single spherical particle deposited on a regular substrate under laminar flow conditions. The substrates are triangular and quadratic arrangements of identical glass spheres. For the latter configuration, the distance between the substrate spheres is varied, resulting in different partial shielding of the deposited particle to the shear flow. For the studied particle Reynolds numbers range between 3 × 10−4 and 3, the critical Shields number is independent from the particle density and from the particle Reynolds number but it depends significantly on the geometry of the substrate. Depending on the spacing between the substrate beads and thus on the exposure of the particle to the flow, we have observed an increase of about 50 percent in the critical Shields number. Studying the onset of particle motion as a function of the orientation of the substrate to the flow direction we find that the critical Shields number changes by up to a factor of 2, which is mainly due to the fact that the particle travels through the troughs of the substrate and hence the shear force in travel direction diminishes if not in line with the flow direction. Besides the critical Shields number we study the initial stage of particle motion by detecting the minimum time that is necessary for maintaining a certain Shields number to change the position of a single particle on the regular substrates. In the range studied, the initial stage of motion on the scale of the substrate's periodicity is mainly governed by the equilibrium particle motion.

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Section: Discussioncontrasting

confidence: 50%

Section: Introductionmentioning

confidence: 85%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Incipient motion of a single particle on regular substrates in laminar shear flow

Agudo

Wierschem

2012

Physics of Fluids

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“…But this number that is specifically defined for fully turbulent flow regimes is no more relevant for a laminar jet as will be studied here after. Several previous studies have focused on the onset of particle motion in laminar flow condition with irregular granular substrates [16,18,29,34] or also regular ones [2]. Based on their results considering a planar impinging liquid jet, Badr et al [5] have concluded that the initiation of grain movement can be satisfactorily predicted by a critical inertial Shields number around 1 for particle Reynolds numbers ranging from 3 to 80, by assuming a simplified expression for the inertial flow stress derived from both laminar and turbulent free plane jet models [41] which therefore seem to be valid for a jet impinging on a granular sample.…”

Section: Introductionmentioning

confidence: 99%

Erosion onset of a cohesionless granular medium by an immersed impinging round jet

Brunier-Coulin¹,

Cuéllar²,

Philippe³

2017

Phys. Rev. Fluids

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To cite this version: AbstractAmong different devices developed quite recently to quantify the resistance to erosion of a natural soil within the broader context of dyke safety, the most commonly used is probably the Jet Erosion Test (JET) in which a scouring crater is induced by impingement of an immersed water jet. A comprehensive experimental investigation on the jet erosion in the specific situation of a cohesionless granular material is presented here. The tests were performed combining special optical techniques allowing for an accurate measurement of the scouring onset and evolution inside an artificially translucent granular sample. The impinging jet hydrodynamics are also analyzed empirically validating the use of a self-similar theoretical framework for the laminar round jet. The critical conditions at the onset of erosion appear to be best described by a dimensionless Shields number based on the inertial drag force created by the fluid flow on the eroded particles rather than on the pressure gradients around them. To conclude, a tentative empirical model for the maximal flow velocity initiating erosion at the bottom of the scoured crater is put forward and discussed in the light of some preliminary results.

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Critical conditions of incipient motion of cohesive sediments

Zhang

2017

Water Resources Research

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The critical condition of incipient motion of cohesive sediments was investigated in a laboratory study. One‐hundred experimental runs were performed with sediment samples by varying the yield stress to determine the relationship between the critical condition of incipient motion and the rheological properties of the cohesive sediments. The results indicate that yield stress is a factor that has a major influence on the incipient motion of cohesive sediments. In addition, the critical Shields parameter is found to be exponentially proportional to the yield stress and inversely proportional to the median grain size. The effect of yield stress on the critical Shields parameter is significant for the cohesive sediments and becomes progressively weaker with increasing median grain size. Furthermore, an empirical formula for calculating the critical Shields parameter of cohesive sediments that includes a rheological term and a gravity term is proposed by introducing the yield stress. According to this formula, a modified Shields diagram is obtained in which the values of the critical Shields parameter for cohesive sediments vary within a band that contains countless curves (instead of on a single line) to reflect the influence of the yield stress. This modification of the traditional Shields curve is effective for fine sediments, but the effects tend to vanish for coarse sediments as the behavior of sediments changes from cohesive to noncohesive. Finally, potential further investigations are discussed.

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Determination of the critical Shields number for particle erosion in laminar flow

Cited by 93 publications

References 11 publications

Incipient motion of a single particle on regular substrates in laminar shear flow

Incipient motion of a single particle on regular substrates in laminar shear flow

Erosion onset of a cohesionless granular medium by an immersed impinging round jet

Critical conditions of incipient motion of cohesive sediments

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