Oops! Forgot to post these earlier! Here's some questions for the next two days' worth of reading...

3.2-3.3

I was quite surprised when at the end of 3.2, we decided to drop the treatment of waves! I did have a question about S-waves before we go on though.

It seemed to me that, with the restoring force coming from the velocity-dependent viscosity, there wouldn't be an S-wave at all - a bit of fluid could never be made to return to its original position at all, even at very small distances. Actually, I guess that means you couldn't have any wave propagating from a one-time disturbance, but a wave that's been going fo
r all time with a continuous forcing term could exist.

3.3 was tricky as well, there were parts of the derivation of Helmholtz's theorem that I didn't quite get, I'll have to go back and stare at them a bit more... I was curious about the "Scalar function P" on page 168 though. Is there any physical meaning to it? It's nicer when the mathematical tricks we use also have a physical meaning, though that might be too much to ask considering how many of them we use :)

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3.4-3.5

Ooh, we know what the Reynold's number is now. It ended up seeming a bit out there - just an order-of-magnitude estimate, not to actually calculate something but to give us an idea of which regime the fluid is in. I'd appreciate a physical example of what "diffusion of vorticity" would look like. Maybe I have an idea, but I'm not sure I'm envisioning it right.