The role of flapping elephant ears in heat dissipation

Elephants are big, and they get hot. Especially in Africa. Thus, from the elephant’s point of view, there’s sometimes an urgent necessity to dissipate excess heat.
elephant_ear_smoke_01

Some investigators have suggested that flapping their large ears (strictly, their ‘pinnae’) could provide a significant heat-loss mechanism. (e.g. Buss, I. O., and Estes, J. A., 1971, ‘The Functional Significance of Movements and Positions of the Pinnae of the African Elephant. Loxodonta Africana, Journal of .Mammalogy, 52, pp. 21-27) But, until 2013, no formal studies had investigated the transient effects of the flapping motion on the elephant pinna’s surface temperature. Prompting Dr. Moise Koffi (of the Department of Academic Affairs, CUNY-Hostos Community College, Bronx, NY, US) along with Prof. Yiannis Andreopoulos and Prof. Latif M. Jiji (both of the Department of Mechanical Engineering, The City College of New York, NY, US) to perform a series of controlled laboratory-based studies. Their experiments included the use of full-sized flapping leather faux elephant ears, silicone heaters, and a smoke machine  – along with computer-model thermal simulation techniques.

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The results of the experiments and simulations not only demonstrated and quantified the efficacy of ear flapping, but also showed (for the first time) the role played by swirling air vortices [see photo below].elephant_ear_smoke_03

 

[…] our results agree with the conclusion reached by previous researchers that the flapping of the pinna should be the main thermoregulatory mechanism of the body temperature of large animals such as African elephants. The present contribution, however in the context of the current understanding, is in identifying the vortical system that is responsible for the heat transfer enhancement
observed in the present work which is further amplified in the case of flexible surface.”

See: The Role of Pinnae Flapping Motion on Elephant Metabolic Heat Dissipation in: The Journal of Heat Transfer, Volume 136, Issue 10.

The $14.95 question : In the light of the new findings, are questions (and answers) like these in need of revision? [thanks to P.H. for the link]

BONUS: The famous Disney cartoon version of elephant ear flapping:

 






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