Forms and Patterns of Viscous and Elastic Threads
58 mins 18 secs,
303.72 MB,
WebM
640x360,
29.97 fps,
44100 Hz,
711.27 kbits/sec
Share this media item:
Embed this media item:
Embed this media item:
About this item
| Description: |
Ribe, N
Tuesday 26th September 2017 - 11:00 to 12:00 |
|---|
| Created: | 2017-10-05 08:50 |
|---|---|
| Collection: | Growth form and self-organisation |
| Publisher: | Isaac Newton Institute |
| Copyright: | Ribe, N |
| Language: | eng (English) |
| Distribution: |
World
(downloadable)
|
| Explicit content: | No |
| Aspect Ratio: | 16:9 |
| Screencast: | No |
| Bumper: | UCS Default |
| Trailer: | UCS Default |
| Abstract: | Some of the most beautiful and easy-to-produce instabilities in fluid mechanics
are those that occur when a thin stream of viscous fluid like honey falls steadily from a certain height onto a solid surface. In addition to the familiar 'liquid rope coiling' effect, one can observe periodic folding with or without rotation of the folding plane; periodic collapse and rebuilding of the hollow cylinder formed by a primary coiling instability; and 'liquid supercoiling', in which the cylinder as a whole undergoes steady secondary folding and rotation. Using a combination of laboratory experiments, analytical theory, and numerical simulation, I and my colleagues have determined a phase diagram for these states in the space of dimensionless fall height and flow rate, and have identified the dimensionless parameter that controls which state or states are observed under given conditions. We have also studied pattern formation in the closely related 'fluid mechanical sewing machine’ (FMSM), wherein a viscous thread falling onto a moving belt generates a wealth of complicated 'stitch' patterns including meanders, alternating loops, and doubly periodic patterns. We have determined experimentally and numerically the phase diagram for these patterns in the space of dimensionless fall height and belt speed, and have formulated a simple reduced (three degrees of freedom) model that successfully predicts the patterns in the limit of negligible inertia. In closing, I shall compare the observed FMSM patterns with those of the ‘elastic sewing machine’ in which a normal elastic thread falls onto a moving belt. |
|---|---|
Available Formats
| Format | Quality | Bitrate | Size | |||
|---|---|---|---|---|---|---|
| MPEG-4 Video | 640x360 | 1.91 Mbits/sec | 836.39 MB | View | Download | |
| WebM * | 640x360 | 711.27 kbits/sec | 303.72 MB | View | Download | |
| iPod Video | 480x270 | 492.72 kbits/sec | 210.33 MB | View | Download | |
| MP3 | 44100 Hz | 249.73 kbits/sec | 106.73 MB | Listen | Download | |
| Auto | (Allows browser to choose a format it supports) | |||||