Title: self-moving active fluids Post by: kram1032 on June 22, 2015, 06:00:42 PM http://www.nature.com/nature/journal/v519/n7544/full/nature14272.html
This amazing work has fluids of varying surface-tension attract and resist unification. This effectively can be used to do computations with fluids without using any kind of motor at all. (This is not perpetual motion: The necessary energy is stored in the droplets and the process comes to a halt when, eventually, the individual droplets DO mix) There are a bunch of really nice suplemental videos to the paper. 9 in total but I'll link the four most interesting ones: http://www.nature.com/nature/journal/v519/n7544/fig_tab/nature14272_SV1.html http://www.nature.com/nature/journal/v519/n7544/fig_tab/nature14272_SV5.html http://www.nature.com/nature/journal/v519/n7544/fig_tab/nature14272_SV6.html http://www.nature.com/nature/journal/v519/n7544/fig_tab/nature14272_SV9.html If nothing else, watch those four videos. Title: Re: self-moving active fluids Post by: Chillheimer on June 22, 2015, 06:56:56 PM :o
is this "awesome"-week or what? :D I don't really understand why this is happening.. what exactly is the source of motion? I understand how 2 drops attract or repell each other. but not that one drop is attracted by another that is repelled, so it ends in a chase.. why? how? what the....? We demonstrate experimentally and analytically that these droplets are stabilized by evaporation-induced surface tension gradients and that they move in response to the vapour emitted by neighbouring droplets. i guess that's why. but i don't understand.. Title: Re: self-moving active fluids Post by: kram1032 on June 22, 2015, 11:49:52 PM Apparently, evaporation-"force" is stronger than solar or wind.
Here's a mini car driven by evaporation: https://www.youtube.com/watch?v=xeLD8u-z-Wg Presumably, those droplets work the same way, except their entire body is their engine. (Or, well, at least their surface is) Title: Re: self-moving active fluids Post by: jehovajah on October 24, 2015, 10:36:13 AM https://m.youtube.com/watch?v=QXrS5HJwMBY Fluid mechanics or dynamics contains many less well known phenomena, which have been initially explored but not applied . Surface Tension is one of those boundaries we know a lot about mathematically and physically but we have only used in a few applications. The key point Chillhelmer is to revise your notions of matter, and I recommend adopting a fluid dynamic paradigm to do so. Then you can make the intuitive leap that all surfaces are active . The viscosity and the momentum of that activity is captured in the Rayleigh number. This provides a scaled way of understanding fluid behaviours. By that I mean the same behaviours at different scales appear very different! Thus a surface of a solid appears rigid, but in fact it is not. It has a very high viscosity but is still active . Glass for example flows very slowly. The forces and energies in these boundary surfaces are phenomenal. It is only now we are beginning to find out how to tap into them. Where fractals come into the picture is precisely in relation to the Rayleigh number. This is a scale free device that allows us to apply iteratively certain forms to all scales just as in a fractal . We then calculate the physical measurement to be expected in the predicted behaviour by truncating the iteration appropriately. Wada basins,Van De Wahl forces etc all can be modelled by a fractal topology. The Casmir forces fall into this category also.essentially "magnetic" behaviours are a way of describing these fractal topologies as they behave. I am not now claiming space is fractal, not any more. Our measurement topologies are best applied fractally to space-like objects and regions. |