Mathematics


Below is a terrific short video examining a missing persons mystery from 1926 using glacier modelling!

The sinking bubbles in Guinness and stouts in general have intrigued drinkers and scientists alike.  Research into this phenomena has been highlighted before on this blog (post linked here).  The latest research published in arxiv (academic paper linked here) demonstrates the importance of the shape of the glass in generating the fluid circulation necessary for the creation of the sinking bubbles.  Numerical simulations and experimentation show that the standard pint glass which has a narrower base cause the falling bubble effect whereas a glass that has a larger base does not i.e. results in rising bubbles.  Essentially the small (nitrogen, as opposed to carbon dioxide used in most beers) bubbles are being carried along by the local fluid motion in the glass and the shape of the glass influences the circulation of the beer as it is poured determining a sinking or rising bubble effect.  More explanation is provided in a BBC news article here.

Apparently my Royal Society article of last year was the journals (Proceeding A) most cited paper of 2011 and the 8th most downloaded.  The illustrious top-ten are listed here: http://rspa.royalsocietypublishing.org/site/misc/top_ten.xhtml Anyway the prize for this accomplishment is that the complete article is freely available online through 2012 (i.e. no journal pay-wall).  So please go ahead and have a look – download and cite the paper some more!

A numerical study of hydrologically driven glacier dynamics and subglacial flooding  by Sam Pimentel and Gwenn E. Flowers

 

A brinicle is essentially an underwater icicle or ice stalactite.  Their growth and formation has been observed for the first time as part of the new BBC series Frozen Planet.  This link reveals how this was captured on film.  Here is the amazing timelapse footage of the formation of a brinicle:

For information on brinicle formation and structure read this BBC article and wikipedia entry.  A mathematical treatment of their formation can be found in this academic paper:

Martin, Seelye (1974). “Ice stalactites: comparison of a laminar flow theory with experiment”Journal of Fluid Mechanics 63 (1): 51-79. doi:10.1017/S0022112074001017

Happy St. Patrick’s Day – Enjoy your Guinness.

Stout is my favourite type of beer.  One of the things that are fascinating about stouts, such as Guinness, are the bubbles.  Firstly, beers are carbonated by carbon dioxide, but stouts use a mixture of nitrogen and carbon dioxide – this makes a creamier as well as less acidic taste and for a longer lasting foam head.  Another thing is that the bubbles sink.  Here’s the science and mathematics of sinking bubbles in Guinness, with the academic paper here.

On tap the bubbles are created by forcing the beer at high pressure through tiny holes as it is dispensed, the turbulence does the rest.  This method obviously doesn’t work for canned beer and this is where the widget comes in.  Apparently recent research suggests that bubbles in stout can be nucleated without the widget by potentially coating part of the can’s interior with cellulose fibres.  Here’s the link to the research, with the submitted academic paper here.