h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I have homework.

Homework is evil.

It involves a lot of complicated math, and basically what I have to do is write an equation relating the channel profile to distance along the stream.

So far, all I have managed to do is prove that when uplift and erosion rates are equal, there is no change in the channel profile.

Way out of my league, good luck

That seems about right

Er...........Sure!

I hate what work I have to do - stupid physiology practical writeups, six hours of work, *grumble*

Still, we have to do it, and it's good in the end!

Traveller in Time housework
"Same principle, try to clear up as much as is left behind.
Strange fenomena: there is always more to be cleaned then you ever can have dropped.

Hydrodynamics. All I can say: fascinating.

There has to be a relation with the profile to the flow speed(s). Like your proof will show; a laminated flow will keep the profile constant, while a turbulent flow makes it chaotic.

Each difference in flow speed creates more turbulence (according to Bernoulli) allowing a wide bed with slow flow should give the most stable profile.

Ther will be two models one with debree, changing the profile into a wide bed. And a model with no moving solid material at all, just for a simple equation.

Back to the beach, building channels and dams ."

Actually, turbulent flows aren't as chaotic as you might thing- on small scales, yes, but the net velocities are pretty easy* to get to. I should probably write a guide article on that...

*Using advanced calculus and Large Scary Equations

Traveller in Time only practical hydrated
"True about the scale of the turbulences, but is it not the small scale at which the particles are lifted ?

I know above the centimeter scale the turbulence is not chaotic. It can go to a resonating state instead. The one thing in electronics I 'fear' more then noise is resonance.

Any change in energetic state seems to create one of both.

I love those boundaries "

It's really not as random as you think. Turbulence moves in bursts and sweeps- what goes up must come down, right? I'll have to see if I can get the website for the animation off my professor, but someone mathematically modelled turbulence, and made an animation out of it. It just looks like these worms, rolling perpendicular to the current- only when they get so far along, Bernouli's lifts them up off the bed, and they deform into sort of horseshoe shapes because the velocity is higher in the center of the channel. I'm not sure if we can actually see this happening, but we know it does because we see current lineations in channel beds- those are the ends of the "turbulence worms" that drag on the bottom after the middle gets lifted up.

Anyway, great news! I got the homework done, and I only had to beg for hints three times!

Of course, I got it done five minutes before class starts, but better five minutes early than late!

Aha! Found it!

http://www.stanford.edu/group/ctr/gallery/images/002_1.gif

There's another animation of turbulence as well. It's on the parent directory to that.

Y'know - I must be a bit of a , but something about using maths to mimic real natural flows really interests me. I very nearly flunked fluid mechanics in college and simply because I didn't "get" it, but since then I have remained very interested in chaotic flows and the mathematics behind it. Something I would definitely look into as a hobby if I won the lottery!

I am currently reading a book "Why most things fail" on chaotic behaviour in economics and I'm finding it truly absorbing. It compares biological extinctions to the failure rates of firms. There is a connection. A big one, and it's turning classical economics on it head. Really good. No, really