Theory of a Vortex
I wrote this article to make 2 goals a success. The goal number one, to satisfy a question of mine (that is obvious because all my articles published here carry answers fro my questions). The second aim is I couldn't be able to find an article which carries this much information about vortices even in Wikipedia. Hope you will enjoy this. By the way if you have any additional facts or noted any corrections regarding this article, please submit them with your name if you like.
NOTE: Plural of vortex is vortices
NOTE: Plural of vortex is vortices
What is a vortex?
- A vortex is a spinning, often turbulent (violent), flow of fluid.
- Any spiral motion with closed streamlines is vortex flow. The motion of the fluid swirling rapidly around a center is called a vortex.
- The speed and rate of rotation of the fluid in a free (irrotational) vortex are greatest at the center, and decrease progressively (little by little) with distance from the center, whereas the speed of a forced (rotational) vortex is zero at the center and increases proportional to the distance from the center.
- Both types of vortices exhibit a pressure minimum at the center, though the pressure minimum in a free vortex is much lower.
Well. Those are the basic facts about a vortex. As we finished with it, let's move on to some harder explanations regarding some aspects of a vortex.
_Properties of vortices
|
- Vortices eagerly deflect and attach themselves to a solid surface.E.g.: A vortex usually forms ahead of the propeller or jet engine of a slow-moving airplane. One end of the vortex line is attached to the propeller or jet engine, but when the airplane is taxiing, the other end of the vortex line readily attaches itself to the ground rather than end in midair.
NOTE: The vortex can suck water and small stones into the core and then into the propeller disk or jet engine.
- Two or more vortices that are slightly parallel and whirl in the same direction will merge to form a single vortex. The circulation of the merged vortex will equal the sum of the circulations of the constituent (containing) vortices.E.g.: A sheet of small vortices flows from the trailing edge of the wing or propeller of an airplane when the wing is developing lift or the propeller is developing a push (thrust). These small vortices merge to form a single vortex.
How the direction of rotation of a vortex changes
- Many of the people believe that a vortex will only whirl to one direction i.e. either in clockwise or anti-clockwise direction (mostly they believe that it is the same direction they’ve seen in their childhoods when they pull out the plug from their bathtubs or sinks- wrong idea of course.)
- Rotation of a vortex in clockwise direction (in northern hemisphere) and anti-clockwise directions (in southern hemisphere) will be triggered mainly on 2 factors.
- They are:
ii. Coriolis Effect (I strongly recommend you, if coriolis effect senses like Greek to you please refer to this link)
- The factors contributing to the circulating direction of rotation of a vortex
Rotation of the earth.
- Looking downward in the northern hemisphere, the ground is rotating counterclockwise as the earth turns beneath our feet (in the southern hemisphere, it rotates clockwise).
- Everything at rest around us, including water in a basin, rotates at the same time.
- The water therefore possesses a small measure of angular momentum (which merely means that it would attempt to keep rotating if the earth stopped).
- If the water is drained through a hole with a diameter smaller than that of the container, the angular momentum must be taken up in a smaller and smaller cross-section.
- When this happens, the rotation increases in the same manner.E.g. skater’s rate of spin increases when she pulls her arms to her sides (took the example from Wikipedia)
Coriolis Effect (Don’t say that you don’t know it now. It took me 2 days to write the article on “the coriolis effect”)
- Coriolis effect, which diverts moving objects (such as projectiles, airplanes, or, in the present case, water) to the right in the northern hemisphere and to the left in the southern hemisphere.
- As long as the water in the basin is at rest, the Coriolis effect plays no role, but, in the northern hemisphere when a plug is pulled and the water begins to move toward the drain, it is deflected slightly to the right.
That is the end of the article. If you expected something more than this please inform me. I'll try my best to answerr it. Anyway thank you again for reading this.