Experimental characterization of flow regimes in various porous media—II: Transition to turbulent regime

Seguin, D.; Montillet, Agnès; Comiti, Jacques; Huet, François

doi:10.1016/s0009-2509(98)80003-1

Cited by 163 publications

(97 citation statements)

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“…Similar observations were also reported earlier for other porous media. [21] At higher values of Fo, that were analyzed only for the artificial foam with e ¼ 50%, the onset of flow unsteadiness occurs. In this regime, the turbulence intensity is observed to increase with the strut shape factor, reaching a maximum value of 7.5% for the realization with the thickest joints, that is, for k ¼ 1:1.…”

Section: Covered Flow Regimesmentioning

confidence: 99%

Influence of Foam Morphology on Effective Properties Related to Metal Melt Filtration

et al. 2017

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In this article, a numerical study on the sensitivity, related to the performance of open-cell foams used for the depth filtration of liquid metals, on two characteristic morphological properties is presented. Therefore, simulations of fluid flow and particle transport inside an artificial foam structure are carried out, whose porosity and strut shape is varied within a certain expected range. For comparison purposes, however, the simulations are also performed for three typical ceramic foam filters (CFF) with pore densities of 20 and 30 PPI, whose geometries are obtained from CT scans. In order to allow for a comparison between the different structures, a reference length is introduced that relies upon the actual ratio of pores per volume. The evaluation is mainly based on the comparison of the hydraulic tortuosity, the viscous and the inertial permeability coefficients as well as the initial filtration coefficient for alumina inclusions, with their size ranging from of 10 to 40 mm at process conditions typically encountered during the aluminum filtration. It is shown that the ratio of filtration coefficient and pressure drop increases with the porosity, while the material distribution between the struts and the joints is less influential. Finally, the article also provides information on the anisotropy of CFFs and on the transition behavior from steady to unsteady flow in open-cell foams.

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Section: Covered Flow Regimesmentioning

confidence: 99%

Influence of Foam Morphology on Effective Properties Related to Metal Melt Filtration

et al. 2017

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“…However, flow visualization studies in porous media showed that turbulent flow occurs at much higher particle Reynold numbers than the critical particle Reynold numbers of 1-15 for the onset of nonlinear flow (e.g., Chauveteau and Thirriot 1967;Dybbs and Edwards 1984;Seguin et al 1998). Critical particle Reynolds number of 300-533 was determined for the onset of the turbulent flow regime using a uniform spheres packing with particle diameters ranging from 0.5 to 8 cm, respectively (Jolls and Hanratty 1966;Latifi et al 1989;Rode et al 1994;Seguin et al 1998), as well as for cylindrical or plate arrangements (Dybbs and Edwards 1984). Hence, a nonlinear laminar flow regime should be considered before fully turbulent flow develops in porous medium.…”

Section: Nonlinear Laminar Flow and Fully Turbulent Flow In Porous Mediamentioning

confidence: 99%

“…Hence, a nonlinear laminar flow regime should be considered before fully turbulent flow develops in porous medium. A smooth transition was observed from nonlinear laminar flow, to the onset of small vortices and eddies in some pore spaces, to eventually, development of fully turbulent flow in the porous medium (e.g., Dybbs and Edwards 1984;Seguin et al 1998). In the literature, this nonlinearity in the laminar flow regime is ascribed to different microscale processes (e.g., Hassanizadeh and Gray 1987;Ma and Ruth 1993;Skjetne and Auriault 1999;Hill and Koch 2002;Nield 2002).…”

Section: Nonlinear Laminar Flow and Fully Turbulent Flow In Porous Mediamentioning

confidence: 99%

“…As described above, the macroscopic transition from laminar Darcy flow, to nonlinear laminar flow to eventually fully turbulent flow, is a gradual process (e.g., Seguin et al 1998). Many experimental datasets on nonlinear flow behavior in granular porous media show that this gradual process can be accurately predicted by the Forchheimer equation (Eq.…”

Section: Nonlinear Laminar Flow and Fully Turbulent Flow In Porous Mediamentioning

confidence: 99%

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The Effect of Grain Size Distribution on Nonlinear Flow Behavior in Sandy Porous Media

et al. 2017

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The current study provides new experimental data on nonlinear flow behavior in various uniformly graded granular materials (20 samples) ranging from medium sands (d 50 > 0.39 mm) to gravel (d 50 = 6.3 mm). Generally, theoretical equations relate the Forchheimer parameters a and b to the porosity, as well as the characteristic pore length, which is assumed to be the median grain size (d 50 ) of the porous medium. However, numerical and experimental studies show that flow resistance in porous media is largely determined by the geometry of the pore structure. In this study, the effect of the grain size distribution was analyzed using subangular-subrounded sands and approximately equal compaction grades. We have used a reference dataset of 11 uniformly graded filter sands. Mixtures of filter sands were used to obtain a slightly more well-graded composite sand (increased C u values by a factor of 1.19 up to 2.32) with respect to its associated reference sand at equal median grain size (d 50 ) and porosity. For all composite sands, the observed flow resistance was higher than in the corresponding reference sand at equal d 50 , resulting in increased a coefficients by factors up to 1.68, as well as increased b coefficients by factors up to 1.44. A modified Ergun relationship with Ergun constants of 139.1 for A and 2.2 for B, as well as the use of d m − σ as characteristic pore length predicted the coefficients a and b accurately.

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“…In this equation, D p is the (averaged) particle diameter U int = U Darcy /φ where φ is bed porosity and U Darcy = Q/A bed where Q and A bed are volumetric flow rate and bed cross-sectional area, respectively. One alternative Re is the pore Reynolds number that also includes porosity and tortuosity, see Seguin et al (1998). Following Hlushkou and Tallarek (2006) Re p is employed in the present paper since it has a clear definition (i.e.…”

Section: Experimental Set-upmentioning

confidence: 99%

Transitional and Turbulent Flow in a Bed of Spheres as Measured with Stereoscopic Particle Image Velocimetry

et al. 2017

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Stereoscopic particle image velocimetry has been used to investigate inertia dominated, transitional and turbulent flow in a randomly packed bed of monosized PMMA spheres. By using an index-matched fluid, the bed is optically transparent and measurements can be performed in an arbitrary position within the porous bed. The velocity field observations are carried out for particle Reynolds numbers, Re p , between 20 and 3220, and the sampling is done at a frequency of 75 Hz. Results show that, in porous media, the dynamics of the flow can vary significantly from pore to pore. At Re p around 400 the spatially averaged time fluctuations of total velocity reach a maximum and the spatial variation of the time-averaged total velocity, u tot increases up to about the same Re p and then it decreases. Also in the studied planes, a considerable amount of the fluid moves in the perpendicular directions to the main flow direction and the time-averaged magnitude of the velocity in the main direction, u x , has an averaged minimum of 40% of the magnitude of u tot at Re p about 400. For Re p > 1600, this ratio is nearly constant and u x is on average a little bit less than 50% of u tot . The importance of the results for longitudinal and transverse dispersion is discussed.

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Experimental characterization of flow regimes in various porous media—II: Transition to turbulent regime

Cited by 163 publications

References 0 publications

Influence of Foam Morphology on Effective Properties Related to Metal Melt Filtration

Influence of Foam Morphology on Effective Properties Related to Metal Melt Filtration

The Effect of Grain Size Distribution on Nonlinear Flow Behavior in Sandy Porous Media

Transitional and Turbulent Flow in a Bed of Spheres as Measured with Stereoscopic Particle Image Velocimetry

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