Publication Date:
2022-05-25
Description:
Author Posting. © Europhysics Letters Association, 2012. This is the author's version of the work. It is posted here by permission of Europhysics Letters Association for personal use, not for redistribution. The definitive version was published in EPL (Europhysics Letters) 98 (2012): 58003, doi:10.1209/0295-5075/98/58003.
Description:
Flow through a saturated, granular, porous medium can lead to internal erosion,
preferential flow enhancement and the formation of channels within the bulk of the medium. We
examine this phenomenon using a combination of experimental observations, continuum theory
and numerical simulations in a minimal setting. Our experiments are carried out by forcing water
through a Hele-Shaw cell packed with bidisperse grains. When the local fluid flow-induced stress
exceeds a critical threshold, the smaller grains are dislodged and transported, thus changing
the porosity of the medium and thence the local hydraulic conductivity and the development
of erosional channels. The erosion is ultimately arrested due to the drop in the mean pressure
gradient, while most of the flow occurs through the channels. These observations are consistent
with a simple theoretical model for channelization in terms of a macroscopic multiphase description
of erosion. We model a dynamical porosity field that evolves along with the volume fraction of the
mobile and immobile grains in response to fluid flow. Numerical solutions of the resulting initial
boundary value problem yield results for the dynamics and morphology that are in qualitative
agreement with our experiments. In addition to providing a basis for channelization in porous
media, our study highlights how heterogeneity in porous media may arise from flow as a function
of the erosion threshold, and thus potentially offers the ability to control channelization.
Description:
We thank DOE NICCR (AM, AK), Harvard-NSF MRSEC
(LM) and the MacArthur Foundation for partial support.
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
Format:
application/pdf
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