Ruy Does Fluids

This is a little blog to document stuff that I do in research. I am particularly interested in fluid dynamics, but this doesn't exclude writing about other stuff.

[ruydoesfluids-blog]

Heart Planes, Maple Seeds and Autorotation

One day I decided to make a paper airplane shaped like a heart, it flew horribly and I started tweaking it around. I added significant amounts of weight to the front end and it resulted in an interesting behavior.  Turns out the heart shape induced large amounts of drag and causes the whole to experience “pseudo-autorotation” (Lugt 1983 Ann. Rev. Fluids.). 

I asked Dr. Sirohi Jayant (my aerospace advisor) about the phenomena and quickly grabbed a couple of maple seeds that he stored in his desk and threw them into the air. I saw the seeds flew in a similar fashion. However my plane can spin in 2 directions and maple seeds in 1!

Turns out that the geometry will cause this high drag, rotational movement that will slow down the plane/seed dramatically. Here’s an interesting link that explains the behavior. (I believe its open to anyone).

http://mappingignorance.org/2013/05/15/autorotating-seeds-to-fly-or-to-die/

I plan on getting a tattoo of this beautiful phenomenon.

I wonder how autorotation will influence the aerodynamics of my autorotating ribbon project. Also, I wonder if I can use the same code to model my paper plane.

[ruydoesfluids-blog]

Yay first post.

I have been working on simulating a narrow, thin, long ribbon with a crossflow across it’s length.

I am using a 1-D model for the structural deformation there’s only vertical bending (due to lift) and torsional deformations across the span axis. There are no warping considerations. There are some details of the structural model to work out still.

For the aerodynamics I am using the vortex lattice method. At the moment the aerodynamics are steady. 

There’s still a lot of work to be done but it looks neat.

The ribbon is eventually going to be allowed to autorotate, does anyone know if unsteady VLM would work to model that? I think not, and I plan on using a full CFD model to account for that.