DOI: 10.5061/dryad.xsj3tx9m0
title: Experimental data of dancing peanuts in beer

description: In Argentina, some people add peanuts to their beer. Once immersed, the
 peanuts initially sink part way down into the beer before bubbles nucleate
 and grow on the peanut surfaces and remain attached. The peanuts move up
 and down within the beer glass in many repeating cycles. In this work, we
 propose a physical description of this dancing peanuts spectacle. We break
 down the problem into component physical phenomena, providing empirical
 constraint of each: (i) heterogeneous bubble nucleation occurs on peanut
 surfaces and this is energetically preferential to nucleation on the beer
 glass surfaces; (ii) peanuts enshrouded in attached bubbles are positively
 buoyant in beer above a critical attached gas volume; (iii) at the beer
 top surface, bubbles detach and pop, facilitated by peanut rotations and
 rearrangements; (iv) peanuts containing fewer bubbles are then negatively
 buoyant in beer and sink; and (v) the process repeats so long as the beer
 remains sufficiently supersaturated in the gas phase for continued
 nucleation. We used laboratory experiments and calculations to support
 this description, including constraint of the densities and wetting
 properties of the beer–gas–peanut system. We draw analogies between this
 peanut dance cyclicity and industrial and natural processes of wide
 interest, ultimately concluding that this bar-side phenomenon can be a
 vehicle for understanding more complex, applied systems of general
 interest and utility.
description: The complete peanut dancing
 phenomenon (of 13 peanuts) was investigated in a 100×100×200 mm-sized tank
 containing 1 litre of lager-style beer. This process was recorded by a
 camera Sony™ Camcorder model FDR-AX53 Zeiss™ (8.57 megapixels) operating
 at 25 frames per second. The process was recorded until the peanuts begin
 to settle to the bottom of the container and the dancing phenomenon stops.
 This end to the process occurs after approximately 150 minutes and is
 associated with the degassing of the beer to the point where bubble
 nucleation can no longer occur at sufficient rates to stop the peanuts
 sinking. Image analysis was carried out manually with Fiji and the MTrackJ
 plugin on the video frames to constrain the size and number of bubbles per
 peanut as well as the peanuts' sizes. The different numbers of bubbles per peanut
 were obtained by multiplying the visible counted value by two. We selected
 three different time windows to execute the image analyses: 2–13 minutes,
 60–64 minutes, and 120–126 minutes after the peanut introduction into the
 beer. Three different videos at these aforementioned time windows are
 available in the electronic supplementary material as movies s1 (starts at
 minute 2), s2 (starts at minute 60), and s3 (starts at minute 120). These
 available movies have a full-HD resolution. The smallest detectable bubble is 50
 microns. In this
 contribution, the videos of s1, s2, and s3 as well as the final values
 obtained after image analyses are available.
description: In order to open the data provided here, the software needed
 are: 1) Notepad or any similar software that can read
 .txt files 2) Spyder or any similar software that can
 read .py (python script files). 3) Any software that
 can read .mp4 files