Swimming and flying [Aerodynamics #21]

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In this video, we cover the aerodynamics of how animals swim and fly. This includes the entire range of shapes and sizes of animals, from whales down to bacteria. We use physical intuition of the Navier-Stokes equations to decompose the forcing mechanisms into (1) added mass; (2) momentum injection; (3) drag-based; (4) lift-based; and (5) viscous-based strategies. We pay special attention to lift-based thrust due to it's widespread use in nature. In addition, we cover how the drag behavior of big fast animals are different from small, slow animals. Swimmers and flyers often do clever strategies for manipulating and interacting with the wake of itself and others through interesting flow features. We are constantly trying to be inspired by nature's designs and incorporate it into our own through a field called bioinspired design.
Free downloadable notes (PDF with white background) can be found at my website: sites.udel.edu...

Опубликовано:

16 окт 2024

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Комментарии : 13

@setsototitipana8433 4 месяца назад

Very educational series, nice and to the point, takes you from everything baby steps. Am interested in learning more about how birds fly, is there a book that you can recommend - something along the lines of bionic wings for drones preferably like the one done by festo

@prof.vanburen Месяц назад

This is a heavy question and I am happy it is more in my area of expertise! In this case, I think it would be more valuable to dive into journal articles and not books. While some books might exist, it's still a vastly growing area of our understanding and researchers first publish their findings in journals---which I think is where the coolest stuff is. One such journal you could look into is Bioinspiration and Biomimetics. Otherwise, I tend to try and follow the work of groups I am familiar with. For example, Prof. David Lentink has always been a go to for someone I check out to see where the state of the art is in bird-like drones. And, even if you don't have paid access to the journal, authors are usually more than happy to share a copy of their work for free if you just email and ask.

@alexbryden2282 2 года назад

Very cool topic, thank you for sharing!

@prof.vanburen 2 года назад

Glad you liked it Alex!

@YitzharVered Год назад

This is so cool! Thank you so much for all these videos! Is there maybe a physics/biology textbook that explains some of the more advanced usages of aerodynamics in nature? I'm assuming a Cheetah running at 65 mph wants to minimize drag! How do the different species of shark and fish that are fitted to different temperatures different in their designs, and does this have to do with the changes density of water due to the temperature?

@prof.vanburen Год назад

I haven't seen anything like what you describe! I have looked for some bioinspired design books, but that covers other topics than fluid mechanics like structures/materials. Animal aerodynamics/hydrodynamics would be neat, for sure.

@Glider517 Год назад

Hi Prof. Van Buren, thanks for taking the time to explain the details of animal based flight. Do you know why so human deigned wings such as gliders and sailing hydrofoils, which are optimized for high efficiency across a wide speed range are typically quite straight whereas fins of pelagic fish (which one would think are optimizing for the same thing) are often quite swept back?

@prof.vanburen Год назад

Ah great question! I assume you refer to the propulsor of fish and swimming mammals and not the secondary fins for stability/maneuvering. I think there are a number of reasons, but it's a relatively open question in research. My thoughts are (1) fish and aquatic swimmers use oscillating propulsion, thus they pass through regions of much higher angles of attack than say a glider---the sweep allows for flow to stay attached longer because it can induce a leading edge vortex (like a delta wing fighter aircraft); (2) the optimization of fish values efficiency but also survivability---they need to be able to accelerate, maneuver, and swim with great speed at times; (3) it could be biological limitation, having fins straight out might lead to much higher moments at the root which muscle/tendon could have trouble with---sweep allows larger planform areas without that root moment spiking. Just some thoughts!

@Glider517 Год назад

Thanks for sharing your thoughts@@prof.vanburen! I hadn't heard of the leading edge vortex contributing to lift in swept wings, what an interesting phenomenon! I assume it would be most applicable to low aspect fins though?