Quantifying bed architecture and pore flow within simulated granular sediment beds by laser induced fluorescence*

Planar Laser-Induced Fluorescence (PLIF) is a robust experimental technique that involves injecting fluorescent dye into a flow field to extract certain characteristics of the flow field being investigated (Crimaldi, 2008). These characteristics include scalar quantities such as species concentrations (Rubol et al., 2018), physical quantities like grain bed architecture (Hilliard et al., 2021), jet clouds (Wu et al., 2018), and flames (Liu et al., 2018), and vector field quantities such as velocity and pressure gradients (Su & Dahm, 1996). Few studies have attempted to extract velocity fields from the actual movement of the fluorescent dye (Tokumaru, P.T., Dimotakis, 1993), and none have attempted it in a porous media. Current work in the field of porous media flow has been focused on hyporheic flow, or flow that travels between the surface and subsurface domains of rivers and streams. This type of flow is essential for benthic communities to survive, as it is the main transport mechanism for nutrients. We propose a novel experimental method where PLIF is utilized in combination with Refractive Index Matching (RIM) to extract a flow field through a homogeneous porous media.