Multiscale Modeling of Gas-Fluidized Beds

Hoef, van der Ma Martin; Ye, Mao; Annaland, van M Martin Sint; Andrews, A. Abraham Eben; Sundaresan, Sankaran; Kuipers, Jam Hans

doi:10.1016/s0065-2377(06)31002-2

Cited by 296 publications

(189 citation statements)

References 93 publications

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“…The DP method deals with the motion of suspended small (granular) particles, taking into account the action of gravity, gas-solid drag forces, as well as particle-particle and particle-wall collisions. In this model, the gas phase is solved on a computational mesh with a length scale exceeding the size of the small particles and the gas-particle coupling is treated by empirical drag relations [10]. The IB method deals with the motion of the large intruder through the continuous phase, enforcing no-slip boundary conditions with the surrounding gas.…”

Section: Model Descriptionmentioning

confidence: 99%

Numerical investigation of the vertical plunging force of a spherical intruder into a prefluidized granular bed

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Kuipers

2014

Phys. Rev. E

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The plunging of a large intruder sphere into a prefluidized granular bed with various constant velocities and various sphere diameters is investigated using a state-of-the-art hybrid discrete particle and immersed boundary method, in which both the gas-induced drag force and the contact force exerted on the intruder can be investigated separately. We investigate low velocities, where velocity dependent effects first begin to appear. The results show a concave-to-convex dependence of the plunging force as a function of intruder depth. In the concave region the force fits to a power law with an exponent around 1.3, which is in good agreement with existing experimental observations. Our simulation results further show that the force exerted on the frontal hemisphere of the intruder is dominant. At larger intruder velocities, friction with the granular medium causes a velocity-dependent drag force. As long as the granular particles have not yet closed the gap behind the intruder, this drag force is independent of the actual intruder depth. In this regime, the drag force experienced by intruders of different diameter moving at different velocities all fall onto a single master curve if plotted against the Reynolds number, using a single value for the effective viscosity of the granular medium. This master curve corresponds well to the Schiller-Naumann correlation for the drag force between a sphere and a Newtonian fluid. After the gap behind the intruder has closed, the drag force increases not only with velocity but also with depth. We attribute this to the effect of increasing hydrostatic particle pressure in the granular medium, leading to an increase in effective viscosity.

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Section: Model Descriptionmentioning

confidence: 99%

Numerical investigation of the vertical plunging force of a spherical intruder into a prefluidized granular bed

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Kuipers

2014

Phys. Rev. E

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“…Our code combines granular dynamics (GD) and computational fluid dynamics (CFD) [9]: The GD part calculates the particle trajectories from Newton's law, with the particle-particle interactions being given by a 3D soft sphere collision model including tangential friction, while the CFD part evaluates the full Navier-Stokes equations for the interstitial air by a finite difference method. The two parts of the code are coupled to account for the effect of the air on the particles, and vice versa.…”

mentioning

confidence: 99%

Coarsening of Faraday Heaps: Experiment, Simulation, and Theory

et al. 2009

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When a layer of granular material is vertically shaken, the surface spontaneously breaks up in a landscape of small Faraday heaps that merge into larger ones on an ever increasing time scale. This coarsening process is studied in a linear setup, for which the average life span of the transient state with N Faraday heaps is shown to scale as N À3 . We describe this process by a set of differential equations for the peak positions; the calculated evolution of the landscape is in excellent agreement with both the experiments and simulations. The same model explains the observational fact that the number of heaps towards the end of the process decreases approximately as NðtÞ / t À1=2 .

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“…In our study, a fluid cell contains typically O(10) particles. Note that for liquidsolid flows, the fluid phase should be treated as incompressible, which requires a solution procedure that is slightly different from what is described in Hoomans et al (1996) and Van der Hoef et al (2006).…”

Section: The Added Mass Contribution Is Implemented In 6th Internatiomentioning

confidence: 99%

Discrete element study of liquid-solid slurry flows through constricted channels

Abbas¹,

Hoef²,

Bokhove³

et al. 2010

AIP Conference Proceedings

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Discrete element model is used to simulate the flow of liquid-granule mixtures in an inclined channel containing a linear contraction. All the relevant particle/particle and particle/fluid interactions are included in the numerical model. The presence of the contraction induces different steady morphologies of the solid phase or the mixture depending on whether closed or open channels are used. These flows behave quite differently depending on the upstream Froude number and the contraction size ratio. The model is first validated by comparing with the existing results for dry granular (glass particles) chute flows (Vreman et al., 2007). Then simulations of a chute of glass particles in water flowing in a closed channel are compared to the dry granular case. With the same solid flux at the inlet, the hydrodynamic forces in the liquid-solid mixture induce higher particle solid volume fractions in the part of the flow containing the solid phase. The streamwise particle velocity (resp. depth of the solid phase) has the same evolution along the channel with smaller (larger) values than in the dry granular flow case.

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Multiscale Modeling of Gas-Fluidized Beds

Cited by 296 publications

References 93 publications

Numerical investigation of the vertical plunging force of a spherical intruder into a prefluidized granular bed

Numerical investigation of the vertical plunging force of a spherical intruder into a prefluidized granular bed

Coarsening of Faraday Heaps: Experiment, Simulation, and Theory

Discrete element study of liquid-solid slurry flows through constricted channels

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