The return branch of viscous fingers
Fluid Dynamics
2007-05-23 v1 Pattern Formation and Solitons
Abstract
We report a simple experiment of two-dimensional pattern formation in a circular Hele-Shaw cell, showing the appearance of a return branch that is equivalent to the upward-connecting leader of lightning. Injecting water from the center into a foam filled cell, we obtained patterns similar to dendrites of two-dimensional dielectric breakdown experiments. When we repeat this experiment allowing the presence of water in the outer (low pressure) region, dendrites grow initially as in a normal experiment, but when a branch is near the outer boundary, the low pressure water begins to penetrate the foam against the pressure field, forming several return branches.
Cite
@article{arxiv.physics/0505125,
title = {The return branch of viscous fingers},
author = {Francisco Vera},
journal= {arXiv preprint arXiv:physics/0505125},
year = {2007}
}