vortex shedding

The wake of a cylinder is a series of alternating vortices shed as the flow moves past. This distinctive pattern is known as a von Karman vortex street. The speed of the flow and the size of the cylinder determine how often vortices are shed. Incredibly, this pattern appears at scales ranging from the laboratory demo all the way to the wakes of islands. Von Karman vortex streets can even be seen from space. (Image credit: R. Gontijo and W. Cerqueira, source video)

So I don’t even have words. This was maybe the saddest episode of all time.

Imagine how lonely it would feel to be a god who wanted to help and managed to break everything. It’s all you have and it’s shattering. And it’s all your fault. 

What is the dark planet with no sun? Even the gods don’t know. 

So we know that the world did end in 1983, like Simone Rigideau always said. It’s just that Huntokar changed things. 

The angels were sent to help Night Vale. But can they do it? 

Loved the parallels with “A Story About You/Them”. Vortex Shedding playing, the narrative style. It’s all very simple, yet poetic, which is one reason I love WTNV so much. 

Can Night Vale* still survive this? What happens if it can’t? I’m so curious to hear what happens. They aren’t ending the show, but surely this will bring about some changes.

I don’t have any deep academic readings of this, I respond to things on an emotional level. I will say this, though: It feels oddly cathartic that there is a caring God behind Night Vale. Not an almighty one, but not all sinister like the other gods. Huntokar actually cares about Cecil and Night Vale. It feels good. I dunno why, but it does. 

* or should I say Night ValeS? 

an instrumental mix for the eerie reality that exists on the wrong side of 3am

soft trees break the fall - trent raznor & atticus ross || who is the Vehicular - disparition || lapis’ tower - aivi & surasshu || the impossible astronaut - murray gold & BBC orchestra of wales || neptune - gustav holst || peridot - aivi & surasshu || vortex shedding - disparition || bill cipher - brad breeck || analog - disparition || to be continued… - brad breeck || indian - sleeping at last || lion’s mane - aivi & surasshu || the whale - mychael danna || message from home - hans zimmer || the rest of my life - hans zimmer || monster - detektivbyrån || little amy - murray gold & BBC orchestra of wales || let her go - hans zimmer || gleypa okkur - olafur arnalds || ende - disparition

[8tracks] [playmoss]

Von Karman vortex streets are a pattern of alternating vortices shed in the wake of a bluff body. They’re commonly associated with cylinders and can be demonstrated in simulation and in the lab. (They even show up in supersonic flows.) But they also show up in nature quite frequently, like in this cloud pattern off Central America. Such wakes often occur downstream of rocky, volcanic islands that rise above the smooth ocean surface and disrupt the atmosphere’s boundary layer. The same phenomenon is responsible for the “singing” of electrical lines on a windy day, and I’ve even heard it make the spokes on my bicycle wheel sing in a crosswind. (Photo credit: R. Mastracchio; via @BadAstronomer; submitted by jshoer)

Flow around an airfoil with a leading-edge slat is visualized above. At this Reynolds number, alternating periodic vortices are shed in its wake. Understanding how multi-element airfoils and control surfaces affect local flow is important in controlling aircraft aerodynamics. When multiple instabilities interact–like those in the wing’s boundary layer interacting with the wake’s–it can generate disturbances that are problematic in flight. Being able to predict and avoid such behavior is important for safe aircraft. (Photo credit: S. Makiya et al.)

2

Sitting at a traffic stop on a windy day, you may have noticed the beam holding the traffic lights shaking steadily up and down. This phenomenon is called vortex-induced vibration. When the wind flows over the beam, it looks something like the flow animation shown above. Airflow follows the shape of the beam until near the backside, where the air separates from the surface and creates a vortex that sloughs off into the beam’s wake. These vortices form asymmetrically on the beam – first on one side, then the other. This creates unequal pressures on either side of the beam, and those pressure differences create a force that moves the beam. Because vortices are being steadily shed off the beam, it will keep moving back and forth as long as the wind is strong enough. (Image credits: traffic light - L. Sennick, source; cylinder - Aphex82/Wikimedia)

  • Q: What was the idea behind the amazing Currents cover?
  • Kevin Parker: the currents album cover was inspired by this type of diagram i remember seeing a few times, that popped in my head when trying to visualize the albums ...themes i guess. I think it's called vortex shedding? basically it's what happens when an object is moving through fluid or air etc, the fluid in front of it is calm and flat, as the object moves through it warps and mangles and leaves this trail of twisted and disrupted fluid. Thats a terrible explanation, I'm sure an actual scientist could do it better...
vimeo

Flow visualization can be a valuable tool for understanding fluid dynamics. In this video, we see how it can help elucidate the mechanisms of flapping flight. By dyeing vortices from the leading edge in red rhodamine and vortices from the trailing edge in green fluorescein, it’s possible to distinguish their competing effects for wings of different size. The speed and efficiency of a flapping wing depends on the vortices it sheds–these provide its lift and thrust. On a short wing, the leading edge vortex is significant and spins in a counter-clockwise (positive) direction. When it reaches the trailing edge, it meets a vortex spinning clockwise (negative). The interference of the two vortices weakens the shed vortex, thereby slowing the wing. Lengthening the wing weakens the leading edge vortex, which reduces its interference at the trailing edge and makes the longer wings more efficient. (Video credit: T. Mitchel et al.; via @AlbanSauret)