The calculations of dispersion coefficients inside two‐dimensional randomly packed beds of circular particles

Abstract

in Wiley Online Library (wileyonlinelibrary.com).The longitudinal (D L ) and transverse (D T ) dispersion coefficients in two-dimensional (2-D) randomly packed beds of circular particles in a laminar flow regime are derived. A 2-D discrete system of particles is divided into cells using modified Voronoi diagrams. The relationship between the variation of the stream function and the averaged vorticity is obtained from computational fluid dynamics (CFD) simulations. The whole flow pattern is then obtained by using the principle of energy dissipation rate minimization. The obtained values of D L agree well with 3-D experimental data for all velocities investigated. At very high velocities, D T in 2-D appears to be higher than 3-D experimental data. In addition, the effects of particle-size distributions, packing structure, and porosity on the D L and D T were studied. One result was that an increase in the width of the particle-size distribution resulted in higher values of D L and D T at high velocities.

Darcy’s Law for Flow in a Periodic Thin Porous Medium Confined Between Two Parallel Plates

“…More precisely, we consider pressure-driven flow through a periodic array of vertical cylinders confined between two parallel plates. The parallel plates make the geometry different from those studied in Chen and Papathanasiou (2008), Gebart (1992), , Hwang and Advani (2010), Jourak et al (2013), Koch and Ladd (1997), , Lundström and Gebart (1995), Sangani and Yao (1988). A representative elementary volume for such TPM is a cube of lateral length ε and vertical length δ.…”

Discrete and continuous modelling of convective heat transport in a thin porous layer of mono sized spheres

“…To exemplify, for flow perpendicular to such a porous medium there can be large variations in velocity of the penetrating fluid as a function of spatial co-ordinate. Results in Jourak et al [22,23], indicate such a behavior. In these studies the dispersion was initially large when resolving the flow around packed beds of parallel cylinders and spheres.…”

Transversal flow-induced deformation of fibres during composites manufacturing and the effect on permeability

“…The initial permeability is slightly lower which could be explained by a larger tortuosity factor. 32 The flowinduced deformations have, however, negligible on the permeability of regular packing (see Figure 3). The small but existing change at u ¼ 0.1 for this case can be accounted by very small irregularity as the system is not precisely regular hexagonal packing but piece-wise regular with each piece containing 200-500 fibres.…”