Capture of particles in soft porous media

We investigate the capture of particles in soft porous media. Liquid foam constitutes a model system for such a study, allowing the radii of passage in the pore space to be tuned over several orders of magnitude by adjusting the liquid volume fraction. We show how particle capture is determined by the coupling of interstitial liquid flow and network deformation, and present a simple model of the capture process that shows good agreement with our experimental data.

Figure 1

(Color online) Capture radius of foams vs liquid flux. Bubble radius $R$ (●) 0.55 mm, (◼) 1.45 mm, (◆) 2.15 mm. Full lines correspond to Eq. (8) (from bottom to top $R$ is equal to: 0.55, 1.45, and 2.15). Dashed line corresponds to Eq. (4) (from bottom to top $R$ is equal to: 0.55, 1.45, and 2.15).

Figure 2

Dimensionless radius of passage in foam as a function of liquid volume fraction. (◻) and (○) correspond to surface evolver calculations for bcc and fcc structures respectively. Full line: Eq. (2). Dashed line: Eq. (3). Dotted line: values deduced from [8]. Sketches illustrate the evolution for the size of foam channels.

Figure 3

(Color online) Drawing of the particle at the entrance of a foam channel. Left: view along the channel axis. Right: view perpendicular to the channel axis.

Figure 4

Evolution of the dimensionless projected contact area multiplied by $\text{sin}\left(\theta \right)$ for $C=20$ as a function of the particle position in the Plateau border. From bottom to top $r_s/r_p$ is equal to: 1.05, 1.1, 1.2, 1.3, 1.4, and 1.5.

Figure 5

(Color online) Ratio of capture radius to passage radius as a function of liquid volume fraction. The Bubble radius $R$ is (●) 0.55 mm, (◼) 1.45 mm, (◆) 2.15 mm. The Full lines correspond to Eq. (8) (from bottom to top the capillary number is equal to: 0.3, 2, and 4).