A Simple Universal Equation for Grain Settling Velocity

Ferguson, Rob; Church, Michael

doi:10.1306/051204740933

Cited by 453 publications

(438 citation statements)

References 8 publications

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“…The ESD derived from the interpolation formula (Eq. 10) (hereafter L int ) indirectly accounts for a nonspherical particle shape by adopting the coefficient values C 1 5 24 and C D 5 0.75, which produce the best fit to experimental data on sinking of slightly nonspherical particles (Ferguson and Church 2004). The resistance drag produced by particles of irregular shape, like zooplankton carcasses, is larger than that produced by a sphere.…”

Section: Results Ii: Carcass Sinking Modelmentioning

confidence: 99%

Modeling sinking rate of zooplankton carcasses: Effects of stratification and mixing

Kirillin

Grossart

Tang

2012

Limnology & Oceanography

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Using the carcass sinking rate and density determined in laboratory for several freshwater zooplankton species, we developed a model of zooplankton carcass sinking as affected by turbulence and stratification. The model was subsequently used to estimate the residence time of zooplankton carcasses in the water column of Lake Stechlin, a typical temperate dimictic lake in northeastern Germany. The residence time varied among the different species and was strongly affected by thermal stratification. At the peak of summer stratification, the carcasses stayed up to 5 d in the 70 m-deep water column before reaching the lake bottom. Residence time was long enough that zooplankton carcasses could serve as an important matter and energy source for bacteria in the lake's pelagic zone and hence have the potential to significantly affect aquatic carbon and nutrient cycling. The proposed model of sinking rates, based on physically sound relationships, can be easily applied to other passively sinking particles, and be integrated into large ecosystem models.

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Section: Results Ii: Carcass Sinking Modelmentioning

confidence: 99%

Modeling sinking rate of zooplankton carcasses: Effects of stratification and mixing

Kirillin

Grossart

Tang

2012

Limnology & Oceanography

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“…But, for such values of Re close to unity in this case, we can no more use the Stokes drag force (valid only for Re 1 ≪ ) in the whole viscous regime or a constant drag coefficient (valid only for Re 1 ≫ ) in the whole inertial regime as was done in [14]. To clarify this point, we propose to connect the two limit regimes with the following empirical expression of the drag coefficient derived from [31]: With an analysis analogous to [14], the rheology obtained for dry granular flows [13] has been extended to steady granular flows down an inclined plane taking into account the influence of the interstitial fluid [15]. Specific rheological laws are achieved for the three regimes which predict in particular that the velocity profiles in both free fall and inertial limit regimes are qualitatively similar.…”

Section: Comparison and Discussion On Velocity Profilesmentioning

confidence: 99%

Sensitivity to solid volume fraction of gravitational instability in a granular medium

Bonnet¹,

Richard²,

Philippe³

2010

Granular Matter

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We report experimental results on incipient dynamics of gravitational destabilization in an immersed granular medium. Two protocols have been used to reach instability: a progressive loading and a dam-break situation. The instability triggering, analyzed by high-speed imaging and CIV post-processing, reveals distinct dynamical behaviours depending on the initial packing fraction of the medium. Two destabilisation modes have been observed: a surface avalanche and a deeper phenomenon that we called circular collapse.

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“…Carcass settling velocity measurements and fresh carcass density were used to estimate carcass ESD using a modified Stokes' Law for irregularly shaped particles (Ferguson and Church 2004) …”

Section: Methodsmentioning

confidence: 99%

“…where v s is particle (carcass) settling velocity, R is submerged specific gravity [(r particle 2r fluid )/r fluid , where r is density], g is gravitational acceleration, D is particle ESD, n is fluid kinematic viscosity, and C 1 and C 2 are constants (24 and 1.2, respectively; as recommended for angular grains by Ferguson and Church [2004]). Measured values of fresh carcass density (r particle ) and settling velocity (v s ) were applied in Eq.…”

Section: Methodsmentioning

confidence: 99%

Dead in the water: The fate of copepod carcasses in the York River estuary, Virginia

Elliott

Harris

Tang

2010

Limnology & Oceanography

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Using laboratory and field experiments we investigated three fates of copepod carcass organic matter in the York River estuary, Virginia: ingestion by planktivores (necrophagy), microbial decomposition, and removal by gravitational settling in the presence of turbulence (sinking). The ctenophore Mnemiopsis leidyi ingested live copepods and carcasses indiscriminately in feeding experiments. Microbial decomposition led to ca. 50% of carcass dry weight loss within 8 h after death. Carcass settling velocities in still water were ca. 0.1 cm s 21 , implying short residence time (hours) in the shallow estuary. However, turbulent mixing kept carcasses in suspension much of the time, reducing sinking losses. Rates of carcass organic matter removal were combined in a simple mathematical model predicting the fate of estuarine copepod carcasses. When sinking was considered, it removed a large fraction of carcass organic matter ($ 58% for copepodites, $ 35% for nauplii), with most of the remainder being removed by microbial decomposition. In the absence of sinking losses, necrophagy became proportionally more important in removing carcass organic matter ($ 49%, except in summer).

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A Simple Universal Equation for Grain Settling Velocity

Cited by 453 publications

References 8 publications

Modeling sinking rate of zooplankton carcasses: Effects of stratification and mixing

Modeling sinking rate of zooplankton carcasses: Effects of stratification and mixing

Sensitivity to solid volume fraction of gravitational instability in a granular medium

Dead in the water: The fate of copepod carcasses in the York River estuary, Virginia

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