An Equivalent Spherical Particle System to Describe Characteristics of Flow in a Dense Packing of Non-spherical Particles

Guo, Peijun; Stolle, Dieter; Guo, Shannon X.

doi:10.1007/s11242-019-01286-y

Cited by 4 publications

(3 citation statements)

References 65 publications

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“…Motivated by a need to evaluate subsurface fluid reserves, these concepts are well‐established in sedimentology, especially for isotropic sediment grains like the spherical siliciclastic model, and increasingly also for irregular grains (e.g. Guo et al ., 2019). Vinopal & Coogan (1978) investigated the packing of skeletal carbonates in physical experiments using discs and cylinders as well as natural sands.…”

Section: Discussionmentioning

confidence: 99%

Shape‐dependent settling velocity of skeletal carbonate grains: Implications for calciturbidites

Slootman

Kruijf²,

Glatz

et al. 2023

Sedimentology

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Particle transport and deposition in turbidity currents is governed by the balance between turbulent suspension and gravitational settling, with settling velocity becoming dominant during the final rain‐out phases of decelerated turbidity currents on lobes. Differential particle settling velocities play a role in the sorting of grains in turbidity currents; there is a preference of grains with higher settling velocities to be deposited first, yielding a settling‐velocity gradient in vertical and longitudinal cross‐sections through turbidite beds. If sediments contain little variation in particle shape and density (for example, siliciclastics), then settling velocity is dominantly controlled by grain size. Carbonate sediments, in contrast, are composed of non‐skeletal and skeletal grains with various growth structures, producing a wide distribution of particle shapes (from spheroidal to platy, bladed and elongated forms). The present paper aims to constrain the extent to which shape‐dependent differential settling velocities influence sorting mechanisms in carbonate turbidity currents. Experiments using natural skeletal sand were conducted to investigate the settling of carbonate grains in: (i) isolation; (ii) suspension clouds; and (iii) turbidity currents. Size, density and shape parameters, including Corey Shape Factor and Zingg diagrams, were analysed using high‐resolution micro‐computed tomography. The slower settling of non‐spheroidal shapes was quantified. In the sinking suspensions, a sorting mechanism operated through differential velocities yielding an abundance of spheroidal grains at the base and enrichment in less‐spheroidal grains towards the top of suspension deposits. This trend was also observed longitudinally in carbonate turbidity currents, for which enhanced advection lengths caused less spheroidal grains to be transported farther into the basin. The effect of particle shape becomes increasingly significant as grain size increases, in particular above medium sand. Carbonate turbidites may therefore be more poorly sorted than siliciclastic turbidites, which is expected to result in lower primary porosity in calciturbidites compared to siliciclastic turbidites.

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Section: Discussionmentioning

confidence: 99%

Shape‐dependent settling velocity of skeletal carbonate grains: Implications for calciturbidites

Slootman

Kruijf²,

Glatz

et al. 2023

Sedimentology

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“…where g [m/s 2 ] is the acceleration due to gravity, d [m] is the characteristic pore length by means of the particle diameter, v [m 2 /s] is the kinematic viscosity of the fluid, n [−] is the porosity, A is the Ergun constant that equals 150 and B is the Ergun constant that equals 1.75 (Ergun 1952). Many variations on the Ergun relation for different kinds of porous media and flow regimes are given in the literature (e.g., Engelund 1953;Irmay 1964;Mac-Donald et al 1979;Du Plessis 1994;Sedghi-Asl and Rahimi 2011;Erdim et al 2015;Guo et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Nonlinear Flow Behavior in Packed Beds of Natural and Variably Graded Granular Materials

et al. 2019

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Under certain flow conditions, fluid flow through porous media starts to deviate from the linear relationship between flow rate and hydraulic gradient. At such flow conditions, Darcy's law for laminar flow can no longer be assumed and nonlinear relationships are required to predict flow in the Forchheimer regime. To date, most of the nonlinear flow behavior data is obtained from flow experiments on packed beds of uniformly graded granular materials (C u = d 60 /d 10 < 2) with various average grain sizes, ranging from sands to cobbles. However, natural deposits of sand and gravel in the subsurface could have a wide variety of grain size distributions. Therefore, in the present study we investigated the impact of variable grain size distributions on the extent of nonlinear flow behavior through 18 different packed beds of natural sand and gravel deposits, as well as composite filter sand and gravel mixtures within the investigated range of uniformity (2.0 < C u < 17.35) and porosity values (0.23 < n < 0.36). Increased flow resistance is observed for the sand and gravel with high C u values and low porosity values. The present study shows that for granular material with wider grain size distributions (C u > 2), the d 10 instead of the average grain size (d 50) as characteristic pore length should be used. Ergun constants A and B with values of 63.1 and 1.72, respectively, resulted in a reasonable prediction of the Forchheimer coefficients for the investigated granular materials.

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“…Most empirical equations used in soil engineering rely on soil characterization rather than on pore space characterization (van Lopik et al 2019(van Lopik et al , 2017Chapuis 2012). The Forchheimer equation is also frequently utilized in numerical modelling and computational fluid mechanics (Guo et al 2019). Continuous use of these equations argues that further study on this topic is of scientific interest and is useful for many industries.…”

Section: Introductionmentioning

confidence: 99%

Convective Acceleration in Porous Media

Gjengedal

2022

Transp Porous Med

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Convective acceleration occurs in porous media flows due to the spatial variations of the nonuniform flow channel geometry of natural pores. This article demonstrates that the influence of convective acceleration in a nonuniform a pore channel is analogous to that of a constricting pipe channel. Their fluid mechanical behaviour can be comparable, provided that their geometrical characteristics are described precisely in the same manner, and from the same point of reference with regards to the fluid velocity in the flow channels. The analogy of the dissipation mechanisms in nonlinear porous media flow to the "minor loss" approach in fluid mechanics of pipes is therefore appropriate. Conventional nonuniform pipe channel geometries obtain dissipation coefficients within the range 0 < CKL < 0.2. These pipe geometries are relevant reference points for natural porous media, and it is thus expected that most natural pore geometries will obtain values within this range. This assumption holds true for the nine different 3D porous media samples presented here. However, the results show that the rate of change in the pore geometry, and consequently the magnitude of induced convective acceleration, depends on: the area ratio a of the pore channel, the angle of approach θ and the rounding of the pore channel geometry. The rounding of the pore channel reduces the dissipation coefficient, as the rate of change becomes smoother along the channel length. The results also indicate that the pore tortuosity increase the magnitude of nonlinear dissipation, in good agreement with pipe flow behaviour. This knowledge can help improve our interpretation of experimental data and enhance the predictability of porous media equations that incorporate the appropriate dissipation coefficients CKL as a variable. Article Highlights The analogy of porous media flow to the "minor loss" approach in fluid mechanics of pipes is appropriate, and the angle of approach θ and the area ratio a of the pore channel govern the magnitude of induced convective acceleration in porous media The rounding of the pore channel geometry reduces the magnitude of induced convective acceleration The tortuosity of a pore influences the dissipation coefficient CKL and increase the magnitude of induced convective acceleration

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An Equivalent Spherical Particle System to Describe Characteristics of Flow in a Dense Packing of Non-spherical Particles

Cited by 4 publications

References 65 publications

Shape‐dependent settling velocity of skeletal carbonate grains: Implications for calciturbidites

Shape‐dependent settling velocity of skeletal carbonate grains: Implications for calciturbidites

Nonlinear Flow Behavior in Packed Beds of Natural and Variably Graded Granular Materials

Convective Acceleration in Porous Media

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