
Department of Physics Papers
Document Type
Journal Article
Date of this Version
10-21-2014
Publication Source
Physical Review E
Volume
90
Issue
4
Start Page
042205-1
Last Page
042205-14
DOI
10.1103/PhysRevE.90.042205
Abstract
We investigate the formation of fingered flow in dry granular media under simulated rainfall using a quasi-two-dimensional experimental setup composed of a random close packing of monodisperse glass beads. Using controlled experiments, we analyze the finger instabilities that develop from the wetting front as a function of fundamental granular (particle size) and fluid properties (rainfall, viscosity). These finger instabilities act as precursors for water channels, which serve as outlets for water drainage. We look into the characteristics of the homogeneous wetting front and channel size as well as estimate relevant time scales involved in the instability formation and the velocity of the channel fingertip. We compare our experimental results with that of the well-known prediction developed by Parlange and Hill [D. E. Hill and J. Y. Parlange, Soil Sci. Soc. Am. Proc. 36, 697 (1972)]. This model is based on linear stability analysis of the growth of perturbations arising at the interface between two immiscible fluids. Results show that, in terms of morphology, experiments agree with the proposed model. However, in terms of kinetics we nevertheless account for another term that describes the homogenization of the wetting front. This result shows that the manner we introduce the fluid to a porous medium can also influence the formation of finger instabilities. The results also help us to calculate the ideal flow rate needed for homogeneous distribution of water in the soil and minimization of runoff, given the grain size, fluid density, and fluid viscosity. This could have applications in optimizing use of irrigation water.
Copyright/Permission Statement
© 2014 American Physical Society. You can view the original article at: https://journals.aps.org/pre/abstract/10.1103/PhysRevE.90.042205
Recommended Citation
Cejas, C. M., Wei, Y., Barrois, R., Frétigny, C., Durian, D. J., & Dreyfus, R. (2014). Kinetics of Gravity-Driven Water Channels Under Steady Rainfall. Physical Review E, 90 (4), 042205-1-042205-14. http://dx.doi.org/10.1103/PhysRevE.90.042205
Date Posted: 13 October 2017
This document has been peer reviewed.