'Two Theories of Jamming Transitions' - Professor Michael Cates, Lucasian Professor of Mathematics
Duration: 1 hour 2 mins
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| Description: | Inaugural Lecture delivered on 4 November 2016 at the Centre for Mathematical Sciences |
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| Created: | 2016-01-28 15:50 |
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| Collection: | Lucasian Inaugural Lecture Series |
| Publisher: | University of Cambridge |
| Copyright: | University of Cambridge |
| Language: | eng (English) |
| Distribution: |
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| Explicit content: | No |
| Aspect Ratio: | 16:9 |
| Screencast: | No |
| Bumper: | minimal black |
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| Abstract: | If drivers on a crowded road try to move slowly they will succeed, but if they try to move faster the result is a stationary traffic jam. Related jamming transitions arise in various other contexts and I will describe theories for two such cases. The first concerns a model of self-propelled repulsive particles, which is relevant to swimming microbes and their synthetic analogues, but could also describe dodgems at a funfair. Here, jamming causes phase separation into dense and dilute regions—an outcome that would, without self-propulsion, require attractions between the particles. The second jamming transition arises on shearing a dense suspension of hard spheres: a free-flowing fluid suddenly solidifies when pushed too hard. This is disruptive in industrial contexts, and can be appreciated in the kitchen by adding a little water to corn-starch or custard powder. I will show how a smooth stress dependence of the mean friction at individual particle contacts leads inevitably to a discontinuity in macroscopic behaviour. |
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