Summertime droplets

I am having a busy summer. I have the usual research paper to finish, and course to update by autumn. Last week I both co-ran a course for the 12 PhD students who are part of the EU RAMP network I and they are part of, and caught up with graduating students and their families, at the summer graduation ceremony. But I do have a bit of time to teach myself something new.

So I am teaching myself some of the basics of the Lattice-Boltzmann computer simulation technique. Above is one of my first simulations, it shows a droplet (in yellow) that I start out stretched, relaxing to a sphere (really a circle as the system is in only two dimensions). The relaxation is driven by the surface tension, which acts at the surface of the droplet and acts to contract its surface — this is why the final droplet is circular as that is the shape with the smallest surface.

The droplet also has viscosity (the property that is low in water but high in honey) which acts as a brake on the surface-tension driven motion. The viscosity is also the thing that causes the wobbling to fade away — viscosity is basically a friction that acts inside the droplet, braking any motion.

The simulation above is hardly state of the art, but it is nice to get something so visual out of playing around with a new technique. Summers always zip by before I have time to do more than about half I’d like to do, but I should have time to play around with this code, have a bit more fun with wobbling droplets.



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