Experimental data of dancing peanuts in beer
Data files
Jun 15, 2023 version files 151.30 MB
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diameters_bubble_peanut.txt
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movie_s1.mp4
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movie_s2.mp4
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movie_s3.mp4
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README.txt
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tracking.txt
Abstract
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.
Methods
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.
Usage notes
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