The drag coefficient and settling velocity of natural sediment particles

Riazi, Amin; Türker, Umut

doi:10.1007/s40571-019-00223-6

Cited by 41 publications

(24 citation statements)

References 19 publications

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“…Using similar values for S f and ρ s , the settling velocity for siliciclastic sands is derived from the Eqs. 9 and 6 following Riazi and Türker 23 .…”

Section: Sediment Transport Mode Analysis Sediment Settling Velocitimentioning

confidence: 99%

“…Guo 7 demonstrated that C D for a given particle can be independent of the particle's settling velocity. Recently, Riazi and Türker 23 considered the drag coefficient (C D ) as a dimensionless quantity that describes the resistance of a particle in a fluid environment 25 , and proposed a new equation for C D that is calculated without directly using the Reynolds number or the settling velocity (Eq. 9): (Fig.…”

Section: Effect Of Drag Coefficient In Settling Velocity C D Is Genementioning

confidence: 99%

“…www.nature.com/scientificreports www.nature.com/scientificreports/ where, a 1 , a 2 , and a 3 are shape dependent constants calibrated for silica sands23 and calculated as Re p , the magnitude of C D independent of sediment type (silica or carbonate) will depend solely on B showing an inherent asymptotic behaviour. However, for carbonate sands, based on the results from Smith and Cheung14 , the C D does not show a clear asymptotic behaviour when plotting the experimental C D as a function of Re p…”

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confidence: 99%

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Improved drag coefficient and settling velocity for carbonate sands

Riazi

Vila‐Concejo

Salles

et al. 2020

Sci Rep

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“…Using similar values for S f and ρ s , the settling velocity for siliciclastic sands is derived from the Eqs. 9 and 6 following Riazi and Türker 23 .…”

Section: Sediment Transport Mode Analysis Sediment Settling Velocitimentioning

confidence: 99%

Section: Effect Of Drag Coefficient In Settling Velocity C D Is Genementioning

confidence: 99%

mentioning

confidence: 99%

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Improved drag coefficient and settling velocity for carbonate sands

Riazi

Vila‐Concejo

Salles

et al. 2020

Sci Rep

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“…Chaotic paths of freely falling and ascending spheres, path instabilities, and transitions in Newtonian fluid have been discussed by many (Jenny et al, 2004;Veldhuis and Biesheuvel, 2007;Horowitz and Williamson, 2010;Zhou and Dušek, 2015;Auguste and Magnaudet, 2018;Riazi and Türker, 2019) and experimentally proven by Raaghav (2019). To investigate the path trajectories expected for our particles, we investigated the state diagram (Zhou and Dušek, 2015) of the Galileo number Ga versus the density ratio ρ p /ρ f in Fig.…”

Section: Path Trajectoriesmentioning

confidence: 99%

Can terminal settling velocity and drag of natural particles in water ever be predicted accurately?

Kramer

Moel²,

Raaghav

et al. 2021

Drink. Water Eng. Sci.

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Abstract. Natural particles are frequently applied in drinking water treatment processes in fixed bed reactors, fluidised bed reactors, and sedimentation processes to clarify water and to concentrate solids. When particles settle, it has been found that, in terms of hydraulics, natural particles behave differently when compared to perfectly round spheres. To estimate the terminal settling velocity of single solid particles in a liquid system, a comprehensive collection of equations is available. For perfectly round spheres, the settling velocity can be calculated quite accurately. However, for naturally polydisperse non-spherical particles, experimentally measured settling velocities of individual particles show considerable spread from the calculated average values. This work aims to analyse and explain the different causes of this spread. To this end, terminal settling experiments were conducted in a quiescent fluid with particles varying in density, size, and shape. For the settling experiments, opaque and transparent spherical polydisperse and monodisperse glass beads were selected. In this study, we also examined drinking-water-related particles, like calcite pellets and crushed calcite seeding material grains, which are both applied in drinking water softening. Polydisperse calcite pellets were sieved and separated to acquire more uniformly dispersed samples. In addition, a wide variety of grains with different densities, sizes, and shapes were investigated for their terminal settling velocity and behaviour. The derived drag coefficient was compared with well-known models such as the one of Brown and Lawler (2003). A sensitivity analysis showed that the spread is caused, to a lesser extent, by variations in fluid properties, measurement errors, and wall effects. Natural variations in specific particle density, path trajectory instabilities, and distinctive multi-particle settling behaviour caused a slightly larger degree of the spread. In contrast, a greater spread is caused by variations in particle size, shape, and orientation. In terms of robust process designs and adequate process optimisation for fluidisation and sedimentation of natural granules, it is therefore crucial to take into consideration the influence of the natural variations in the settling velocity when using predictive models of round spheres.

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“…Besides free falling of a single solid object, sedimentation of multiple solid particles has long been an interesting and fundamental subject bearing many significant industrial applications, such as paper making, specialty chemicals, petroleum, bioengineering, pharmaceuticals, biomass gasification, and combustion. Even today, it is still under extensive and intensive study theoretically, numerically, and experimentally [9][10][11][12][13][14]. This motivated us to study sedimentation of multiple circular disks here in order to understand interaction dynamics among solids, besides fluid-solid interaction, during settling.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Freely Falling Objects Using Direct-Forcing Immersed Boundary Method

et al. 2020

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The fluid-structure interaction of solid objects freely falling in a Newtonian fluid was investigated numerically by direct-forcing immersed boundary (DFIB) method. The Navier–Stokes equations are coupled with equations of motion through virtual force to describe the motion of solid objects. Here, we rigorously derived the equations of motion by taking control-volume integration of momentum equation. The method was validated by a popular numerical test example describing the 2D flow caused by the free fall of a circular disk inside a tank of fluid, as well as 3D experimental measurements in the sedimentation of a sphere. Then, we demonstrated the method by a few more 2D sedimentation examples: (1) free fall of two tandem circular disks showing drafting, kissing and tumbling phenomena; (2) sedimentation of multiple circular disks; (3) free fall of a regular triangle, in which the rotation of solid object is significant; (4) free fall of a dropping ellipse to mimic the falling of a leaf. In the last example, we found rich falling patterns exhibiting fluttering, tumbling, and chaotic falling.

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The drag coefficient and settling velocity of natural sediment particles

Cited by 41 publications

References 19 publications

Improved drag coefficient and settling velocity for carbonate sands

Improved drag coefficient and settling velocity for carbonate sands

Can terminal settling velocity and drag of natural particles in water ever be predicted accurately?

Numerical Investigation of Freely Falling Objects Using Direct-Forcing Immersed Boundary Method

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