Time-resolved 3D visualization of air injection in a liquid-saturated refractive-index-matched porous medium

Abstract

The main goal of this work is to implement and validate a visualization method with a given temporal/ spatial resolution to obtain the dynamic three-dimensional (3D) structure of an air plume injected into a deformable liquid-saturated porous medium. The air plume develops via continuous air injection through an orifice at the bottom of a loose packing of crushed silica grains. The packing is saturated by a glycerin-water solution having the same refractive index and placed in a rectangular glass container. By using high-speed image acquisition through laser scanning, the dynamic air plume is recorded by sequential tomographic imaging. Due to the overlap between adjacent laser sheets and the light reflection, air bubbles are multiply exposed in the imaging along the scanning direction. Four image processing methods are presented for the removal of these redundant pixels arising from multiple exposure. The respective results are discussed by comparing the reconstructed air plume volume with the injected one and by evaluating the morphological consistency of the obtained air plume. After processing, a 3D dynamic air flow pattern can be obtained, allowing a quantitative analysis of the air flow dynamics on pore-scale. In the present experimental configuration, the temporal resolution is 0.1 s and the spatial resolution is 0.17 mm in plane and about 1 mm out of plane of the laser sheet.

Quantification of Fluid Saturations in Transparent Porous Media

“…The use of transparent porous media allows relatively inexpensive measurements to be made at high spatial and temporal resolutions for greater sample depths than are possible using light reflection or transmission techniques. In some applications, transparent porous media also allow the reconstruction of three‐dimensional behavior using laser scanning (Ovdat and Berkowitz, 2006; Kong et al, 2011) or multiple cameras (Kashuk et al, 2015).…”

Two-Phase Flow: Structure, Upscaling, and Consequences for Macroscopic Transport Properties

“…In addition, when the porous medium is deformable, branching structures can be observed with transitions to fracturing of the porous medium (Lemaire et al, 1993; Cheng et al, 2008; Sandnes et al, 2011; Holtzman and Juanes, 2010; Chevalier et al, 2009; Johnsen et al, 2006; Varas et al, 2011) or the formation of fingers, channels, or bubbles in it (Johnsen et al, 2006, 2008a, 2008b; Kong et al, 2011; Vinningland et al, 2007a, 2007b, 2010, 2012; Niebling et al, 2010a, 2010b).…”

Shadow imaging in bubbly gas–liquid two-phase flow in porous structures

“…Investigations of two-phase flows with index matching was also done in the past. Kong et al (2011) visualized air injection in a liquid-saturated porous medium. They illuminated plane wise by a laser using a rotating prism for time-resolved measurements.…”