Fluid Dynamics


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.

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Here is another beautiful movie showing ocean fluid patterns (previous post here).  This time we have a numerical simulation of the discharge of fresh water from the Amazon River entering the saltwater of the Atlantic Ocean.  The ocean model (Mercator Ocean) simulates sea surface temperatures over a 3 year period.

HT FYFluidDynamics

A few weeks ago I posted on a stunning video capturing computer simulated ocean current patterns.  Today I’m posting on surface wind flow patterns over the contiguous United States.  Both show the visual beauty of these large-scale fluid flow patterns.  You have to follow this link to view live moving imagery which is based on near-term surface wind forecasts.  Do check out the moving fields, but shown below are some snap shots showing some of the patterns that get generated.

http://hint.fm/wind/gallery/

Here is a really neat film illustrating the amazing surface flow patterns of the oceans.  The footage is generated from simulations of a NASA ocean circulation model.  Eddy swirls and current flow lines are beautifully visualized (some have noted a similarity to van Gogh’s Starry Night).  The most striking patterns of the global ocean circulation include the Gulf Stream, Agulhas rings, and the Kuroshio Current.