dorsal/arxiv
View SchemaDry microfoams: Formation and flow in a confined channel
| Authors | Jan-Paul Raven, Philippe Marmottant, François Graner |
|---|---|
| Categories | |
| ArXiv ID | physics/0510100 |
| URL | https://arxiv.org/abs/physics/0510100 |
| DOI | 10.1140/epjb/e2006-00197-6 |
Abstract
We present an experimental investigation of the agglomeration of microbubbles into a 2D microfoam and its flow in a rectangular microchannel. Using a flow-focusing method, we produce the foam in situ on a microfluidic chip for a large range of liquid fractions, down to a few percent in liquid. We can monitor the transition from separated bubbles to the desired microfoam, in which bubbles are closely packed and separated by thin films. We find that bubble formation frequency is limited by the liquid flow rate, whatever the gas pressure. The formation frequency creates a modulation of the foam flow, rapidly damped along the channel. The average foam flow rate depends non-linearly on the applied gas pressure, displaying a threshold pressure due to capillarity. Strong discontinuities in the flow rate appear when the number of bubbles in the channel width changes, reflecting the discrete nature of the foam topology. We also produce an ultra flat foam, reducing the channel height from 250 $\mu$m to 8 $\mu$m, resulting in a height to diameter ration of 0.02; we notice a marked change in bubble shape during the flow.
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"abstract": "We present an experimental investigation of the agglomeration of microbubbles\ninto a 2D microfoam and its flow in a rectangular microchannel. Using a\nflow-focusing method, we produce the foam in situ on a microfluidic chip for a\nlarge range of liquid fractions, down to a few percent in liquid. We can\nmonitor the transition from separated bubbles to the desired microfoam, in\nwhich bubbles are closely packed and separated by thin films. We find that\nbubble formation frequency is limited by the liquid flow rate, whatever the gas\npressure. The formation frequency creates a modulation of the foam flow,\nrapidly damped along the channel. The average foam flow rate depends\nnon-linearly on the applied gas pressure, displaying a threshold pressure due\nto capillarity. Strong discontinuities in the flow rate appear when the number\nof bubbles in the channel width changes, reflecting the discrete nature of the\nfoam topology. We also produce an ultra flat foam, reducing the channel height\nfrom 250 $\\mu$m to 8 $\\mu$m, resulting in a height to diameter ration of 0.02;\nwe notice a marked change in bubble shape during the flow.",
"arxiv_id": "physics/0510100",
"authors": [
"Jan-Paul Raven",
"Philippe Marmottant",
"Fran\u00e7ois Graner"
],
"categories": [
"physics.flu-dyn",
"cond-mat.soft"
],
"doi": "10.1140/epjb/e2006-00197-6",
"title": "Dry microfoams: Formation and flow in a confined channel",
"url": "https://arxiv.org/abs/physics/0510100"
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