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Numerical simulation of the particle settling in a Bingham fluid using the two-way coupling CFD-DEM scheme

Casarin Joviano Janjar, Franco Admilson Teixeira, Germer Eduardo Matos, Pivovarski Roderick Gustavo

Journal of Theoretical and Applied Mechanics

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2022

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Vol. 60 nr 3

409--422

EN

The computational fluid dynamics coupled with the discrete element method is widely employed to simulate particle-fluid interactions in solid-liquid flows. The restrictions imposed by the CFD-DEM scheme to very fine meshes contribute to a scant amount of numerical results of particle settling in viscoplastic fluids. This paper presents the two-way coupling CFD-DEM simulation of the particle sedimentation in a quiescent Bingham fluid. The results for terminal particle velocity showed good agreement with the experimental data. Owing to the viscoplastic behavior of the fluid, low values of the relaxation parameter of the solid-phase must be specified to obtain accurate results.

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Dynamics of thin disk settling in two layered fuid with density transition

Mrokowska Magdalena M.

Acta Geophysica

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2020

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Vol. 68, no. 4

1145--1160

EN

Settling of solid particles in a stratifed ambient fuid is a process widely encountered in geophysical fows. A set of experiments demonstrating the settling behaviour (the pattern of trajectory, variation of particle orientation, and settling velocity with depth) of thin disks descending through a nonlinear density transition was performed. The results showed complex hydrodynamic interactions between a particle and a liquid causing settling orientation instabilities and unsteady particle descent in low to moderate Reynolds number regime. Five phases of settling were observed: two phases with stable horizontal, one with stable vertical disk position, and two reorientation phases; moreover, two local minima of settling velocity were identifed. It was demonstrated that thresholds for local minima and the frst reorientation depend on the settling dynamics in an upper layer, stratifcation conditions, and disk geometry. The comparison of settling behaviour of thin disks varying in diameter revealed that settling dynamics is sensitive to particle geometry mainly in the upper part of density transition with a non-obvious result that the frst minimum velocity is smaller for a disk with a larger diameter than for a disk with a smaller diameter. The analysis of settling trajectory showed that two reorientations are accompanied with a horizontal drift, which may be important in the context of interactions between particles settling in a group.

3

Selected methods of measuring drilling mud settling

Zwierzyński A.J., Wróblewski T., Wiśniiowski R., Stryczek S.

AGH Drilling, Oil, Gas

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2014

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Vol. 31, no. 4

471--483

EN

Methods of measuring settling rate of drilling muds have been selected and the basic theoretical data on this process are addressed in the paper. A brief discussion is also given on the negative influence of settling in drilling mud on the stability of wellbore and formation of potential drilling complications. The results of an analyses of the settling processes taking place in oil-based muds made according to 8 recipes are presented. The direct weighing method has been used in the measurements.