Have you seen... [crystallization]

Here are two cool illustrations of materials crystalizing - both the effect and the crystals' appearance are neat.

The first video uses a super-saturated solution of sodium acetate, and the demonstrator triggers the reaction with a single crystal.  In his second display, he pours the solution onto crystals, and the resulting growth occurs so quickly that it forms effectively a stable stalagmite on the plate!

You'll have to pardon the voiceover on the next video -- it sounds like he's in the witness protection program.
The experimenter uses a solution of silver, and crystallization requires some electrical current applied.
He repeats the process with a higher current (crystallization occurs much faster) and with a solution of silver nitrate.  When viewed through his microscope, the effects (some time-lapsed) are beautiful and fascinating.

Have you seen... [Newton's beads and Newtonian liquid]

There are more interesting phenomena with "newtonian" materials...

First, "Newton's beads" (and goopy liquid molecules) use gravity for all it's worth:

Second, a Newtonian liquid creates an unexpected effect when being poured into a different flowing liquid:

I would love to be one of those guys that does fun science demonstrations in schools, on TV, etc.!

Hello, Winter

While Herr J just posted about Autumn in Munich, the painful truth is that autumn here is incredibly short.

Saturday, we enjoyed what likely will be one of our last lunches outside.

Zwiebelrostbraten with Käsespätzle is definitely in my top 5 meals - especially when it's from Augustiner am Dom! You did have to protect the food a bit from the falling leaves.

 

And Sunday brought the end of daylight savings...which means colder weather and dark evenings. Winter definitely is here, but it does have one upside....an excuse to break out the snowboarding penguin flannel sheets! They always make me laugh a little, but I love them.

 

Have you seen... [smoke rings & bubbles]

When air in a container is forced through a circular opening, the edge of the opening will create a vortex ring.
Wikipedia helps illustrate what a vortex "looks" like:

In the real-world, we can see this turbulent effect in smoke rings - the particles make the phenomenon visible.
But why let smokers have all the fun, when you can make or buy a vortex ring bazooka!  (Smoke not included.)

Here is Ellen having fun with an easy, homemade air vortex contraption on one of her shows:

In rare cases, a volcano will create a massive smoke ring sending it hundreds of feet into the sky:

A completely different playground activity usng air with another material is the creation of soap bubbles.

Soap film "stabilizes" the surface tension of water and makes sustained (short-term) structure possible.
Like oil on water, the colors we see are created by reflection and refraction of light on the surface.
The light's frequency (phase) is shifted differently, based on the thickness of the soap film on the bubble.

It's a favorite children's activity, but in the second video a "bubble artist" shows just how far this can go.
He creates "doughnut" (torus) shapes, bubbles with smoke in them, and bubbles within bubbles.
And he got a grant from the U.S. government to mess around with bubbles too - why didn't I think of that?

Have you seen... [laminar fluid flow]

The video below is not the most dramatic or exciting... until a subtle surprise at the end.

Here's how it starts:  drops of three colored fluids are placed in a small container of water.  A crank is turned at the top that forces the water to circulate.  After a 6 1/2 revolutions the colored drops of liquid are pretty well "mixed" and the person stops, then starts turning the crank slowly and steadily in the opposite direction...

Cool huh?  You might think this was just video done in reverse, to get the colored drops to re-form like that.
But it is the result of highly laminar flow -- very little turbulence (mixing) -- that keeps everything "in parallel" and the "mixing" therefore becomes a "reversible" action!  (Note that this demonstration is also enabled by the fact that the colored liquid drops have a higher viscosity than the surrounding water.)

One can take advantage of the steady, parallel properties of laminar flow in water fountains.
By ensuring laminar behaviour, water streams will hold their shape.  Even further, light can be projected onto or into the stream (where it reflects back & forth inside the stream) -- this creates neat visual effects.

It can be mesmerizing.

The water fountain in the next video adds two more tricks to the show.  First, the water is pulsed on & off to give a projectile-like effect,  Second, some water streams are aligned so that they collide in midair, and where they meet become a shower of (turbulent) droplets.  This was installed at a casino, no surprise there!

I 've enjoyed a similar fountain at the Detroit Airport during some travels.  Hope to see more around.

The Best Oktoberfest Ever

Anyone who knows me knows I love Oktoberfest.  But since I love dressing up, silly songs, and carnivals, it should be no surprise. Only Bavaria can outdo the Texas State Fair!  (I still need to take Herr J to that...he's never been!)

Due to work travel committments, I was only able to go to Oktoberfest twice this year - we actually had to give up tickets we'd booked in the Kaiserschmarrn tent because I was out of town.  Fortunately, when I returned, we went with friends for a long Sunday and made the most of everything the Wies'n has to offer. 

On the last Friday of Oktoberfest 2011 we squeezed in a short visit, before heading out on an early Saturday morning flight to a week of vacation:  a Pyrennees hiking adventure.  Seeking refuge from the crowded tents, we instead had a lovely picnic dinner (Spanish ham and cheese, and of course German beer) on the hill overlooking the grounds, in front of the Bavaria statue.

And here, Herr J asked me to marry him.

Best. Oktoberfest. EVER.

Looking forward to many years of trachten with this wonderful man! 

Have you seen... [non-Newtonian fluids]

It's great when nature throws us a curveball.  (E.g., most liquids contract when frozen, but water expands).

Most fluids are "Newtonian", meaning that they continue to behave basically the same way no matter how they are being manipulated (stirred, shaken, flowing in pipes, etc.).  It will always act like we expect it to.

A non-Newtonian fluid, however, can demonstrate unexpected viscosity in certain situations.
Everyday substances found in ketchup, custard, paint, and shampoo can result in non-Newtonian fluids.  In the first video, a simple starch solution on a loudspeaker cone shows how unusually the fluid behaves when disturbed.

Many liquid polymers are non-Newtonian, and also exhibit the Weissenberg effect.  Without going into detail, this effect is that the fluid is not thrown off a spinning rod, but drawn into and across the rod (in this case, going up)!

The Kaye effect is another fluid phenomenon.  In this case, when a viscous fluid like shampoo is poured onto another liquid, something about the surface tension and interaction create a second stream coming up.  Interesting...