Whirlpool

In this item, I explain the design of the fluid. Please see "a whirlpool" (vagueness evasion) about the work names.

Whirlpool

The vortex that a current hits the rock (stone), and occurs

Whirlpool (I color it with color smoke) to make of the plane

The typhoon that I saw from the space

Spiral Milky Way NGC 1300 (Hubble Telescope /NASA/ESA)

The vortex (whirlpool) is a spiral pattern that a fluid and a similar object turn and occur. I say eddy (eddy).

Table of contents

General statement

Even a liquid may produce even gas. There are whirling currents (whirling current) occurring at a whirlpool, the straits when I outrun a whirlpool of the water in the washing machine, the water of the bath for the thing which is familiar to people in the vortex that the water causes. A whirlpool of gas includes a tornado, a typhoon. It is interesting in the daily life, but the understanding of the whirlpool and the use or measures may become important from an engineering-like viewpoint science. As study, hydrodynamics, meteorology, aeronautical engineering, marine engineering sell it.

Origin (in the case of autogenesis)

There is the opinion that generally described a natural whirlpool formation phenomenon to occur. That when two different things touch it in fluids qualitatively, according to it, a whirlpool is formed by all means [¹]. Following eight are exemplified as a qualitative example. (liquid, solid) (liquid, gas) (速, 遅 )( 温, cold water) (thin body) (重 light) (viscosity, fluidity) (the alkaline acidity)

Representative whirlpool

• Tornado - typhoon
• Naruto Whirlpools
• The Milky Way

Whirlpool with the hydrodynamics

In the hydrodynamics, I divide a fluid into a minute element. When pay the attention to one element of these microelements which distributed; the exercise,

1. Translation of the whole element
2. Rotary motion on having considered an element as a rigid body
3. Exercise by the pure distortion

I distribute に and can think. As for the one which is important in a whirlpool, 2 is a part about the の turn.

As for the state of the turn of the microelement, in next vorticity w (=w(x, t), x, position coordinate, t of the fluid are expressed at time by).

${\displaystyle {\boldsymbol {w}}(x,t)=\operatorname {rot} \,{\boldsymbol {v}}(x,t)}$ 

Here,${\displaystyle {\boldsymbol {v}}(x,t)}$ Speed, rot of the は fluid are rotations.

Furthermore,

${\displaystyle \operatorname {rot} \,{\boldsymbol {v}}={\boldsymbol {0}}}$ 

But, it is the condition without the whirlpool, and this case, fluid perform the exercise that the vortex is not accompanied by. Therefore,

${\displaystyle \operatorname {rot} \,{\boldsymbol {v}}\neq {\boldsymbol {0}}}$ 

In となる, a whirlpool (exercise) exists somewhere of the exercising fluid.

When there is viscosity in a fluid, vorticity spreads. Therefore, I often ignore whether you treat the viscosity as extremely weak (small) when you treat a whirlpool.

Rankine whirlpools are considered as a model of the whirlpools simplified mathematically.

When there is the vortex, I it

When they are collected at the position with the fluid suddenly, I often produce a whirlpool. For example, the water in the bath basin gathers all here because the water of the circumference flows out of here when I uncork the bottom of the bath basin in the state that water is in the bath.

When each part of the water has a horizontal momentum then for a direction toward the position, I will gradually move towards the center while performing the rotary motion around the position. Then, by law of conservation of angular momentum, the rotary speed increases. Because each part will have the momentum of different directions, I gradually clash and come to really perform the turn of the constant direction before long.

The large-scale whirlpool on the earth such as the typhoon becomes clockwise in counterclockwise direction, the Southern Hemisphere in the Northern Hemisphere. This is because Coriolis force acts. Specifically, I refer to an applicable clause. In addition, I may be said in this way about the small whirlpool, but this is not necessarily right.

In the case of a washing machine, I let water cause rotary motion by adding a rotor blade to the bottom of the bathtub. However, it is hard to get an effect to push it, and to be similar to washing and washing under running water only by laundry unidirectionally really working by this exercise. By a technological change, I change the rotatory direction in a short time, and the washing machine not to prepare the whirlpool into appears.

Footnote

1. For ^ Theodor Schwenk "natural philosophy Toshio Akai reason of the chaos", work building, 1,986 years, it is page 133

Allied item

• Whirlpool thread
• Spiral
• Eddy current
• Whirlpool diffusion
• Light whirlpool
• Karman whirlpool
• Coriolis force
• Die loss (cyclone-type vacuum cleaner using a whirlpool)
• Mosquito-repellent incense - naruto

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