Circumfluence (the Chinese phonetic alphabet is hu á n li ú), a Chinese word, refers to the winding ground flow.That is, in the flow system, try to make all or part of the fluid circulate along a certain direction and path.
1. Loop and zigzag flow.ChineseLiu Xiang《Shuoyuan·Miscellaneous Remarks:“ConfuciusSeeing Luliang,Suspended waterForty feet, ninety miles. "brightZheng ZhenThe poem "Inscription of Painting": "Ten thousand people stand on the cliff, and two streams of clear water circulate."
Energy input is required to generate circulation, which can be usedMechanical pumpOr enter anotherHigh velocity fluidTo input energy to ensure the implementation of circulation.[1]
Fluid science
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circulation
Circulation: the flow inside the bend is in spiral motioncross sectionThe projection on the shows a circular flow.Also called“Transverse circulation”、“Bend circulation”。The water flows along the bendCurvilinear motionWhencentrifugal force, under the action of centrifugal force,concave bankThe water level rises and the convex bank water level decreases.At the same time, due to the large velocity of water surface and the large centrifugal force, the water flow in the upper layer points to the concave bank;The flow velocity at the bottom of the river is small, and the centrifugal force is small. The flow at the bottom of the river points to the convex bank, forming a transverse circulation.
However, the transverse circulation is not carried out on the cross section. The transverse circulation is combined with the longitudinal flow, presenting a spiral flow moving downstream.There may be a large circulation in the bend, or several circulation in different sizes. The circulation may occupy the whole cross section or only a part of the cross section.The transverse circulation is the power that causes the transverse movement of sediment, which causes the concave bank of the bend to be scoured and the convex bank to be silted up.[1]
physics
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For design engineers, circulation can cause devastating disasters, whether your equipment is a computer orcommunication system 。Some engineers lack a correct understanding of circulating current, because a grounding symbol or common symbol is usually used on the schematic diagram to indicate the return path of all circuits.Junior engineers often misunderstand this symbol and think that it represents zero impedance.This is not the case. The grounding symbol only represents one kind of circuit on your schematic diagram.If the current in the grounding connection is large enough or changes fast enough, a considerable voltage will be generated, which may affect the accuracy of the power supply.
In addition, in instrument applications, this voltage can also causemeasurement error, numberSystem EngineerIt is necessary to make efforts to deal with groundingbounceQuestion.Audio Buffer There will be terribleGround Loop InCirculation effect, it will causeBuzzerAnd humming.RF engineers always try to control the flow of ground current in high-frequency system equipment.
Circulation can be harmfulPower circuit, audio circuit and RF circuit.Even IC designers must strive to cope with the effects of circulation.
When considering the trouble caused by circulating currentAC impedanceIt is more important than resistance.
The common symbol or grounding symbol in the schematic diagram is just another kind of circuit and does not represent zero impedance.
The output current of the power supply is large, and the internal circulation is also large.The reference ground should be kept away from these nodes.The power circuit should be connected to your system at one point.
Cutting the ground plane usually causes more trouble.But when allAnalog circuitThere are some exceptions to this rule.
becauseequatorThe regional temperature is high, the air flow expands and rises, the upper air pressure is highBarometric gradientUnder the influence of force, the air flow flows in the polar direction.Againcoriolis force When the air flow moves to 30 degrees north latitude, it will accumulate and sink, making the surface pressure in this area higher, and this area is located in the subtropical zone, soSubtropical high。The surface pressure in the equatorial region is low, soEquatorial low pressure zone。On the surface, air flows from high pressure to low pressure, forming a low latitude circulation.
Mid latitude circulation and high latitude circulation
On the surface,Subtropical zoneThe air pressure in the high pressure area is higher, so the air flow flows in the polar direction.staypolar regions As the temperature is low, the air flow shrinks and sinks, and the air pressure is high, the air flow flows toward the equator.The air flow from the polar region and the air flow from the subtropical zone meet at around 60 degrees, formingfrontal surface, calledPolar front。The air flow in this area is forced to rise, thus forming an epipolar regionLow pressure zone。After the air flow rises, it splits at high altitude and flows to the subtropical zone and the polar region, forming the mid latitude circulation and high latitude circulation.[1]
Ocean circulation
On the sea surface wind andHot saltUnder the action of, the sea water flows from one sea area to another, and finally flows back to the independent circulation system or current cyclones connected head to tail in the original sea area.The ocean surface circulation is closely related to the wind distribution.In addition to horizontal circulation, there is also vertical circulation, namelyUp-down flow(SeeUpflow，Downflow）。
In the low latitude waters north and south of the equatorSoutheast trade windandnortheast tradesFrom east to westEquatorial currentAnd the northern equatorial current, which are blocked by the western coast of the ocean and raise the water level in the west (by 4 cm per 100 km). The main tributaries flow south and north respectively, and a small tributary flows north and south respectively, converging near the equator and raising the water level, thus forming a west to eastEquatorial countercurrent。
circulation
In the mid latitude sea area of the Northern Hemisphere, the main northward tributaries are driven by the prevailing westerly wind at sea and turn to flow eastward, forming the North Atlantic Current and North Pacificocean current, are blocked by the east coast of the ocean and are divided into two tributaries, one to the south and the other to the north.In the Southern HemisphereMid latitudeIn the sea area, the southward main tributary receivesPrevailing westerly windDriving away, it becomes the Antarctic Circumpolar Current flowing from west to east, and there is no barrier from the coast to form the Antarctic Circumpolar Current flowing around the earth.In the Southern HemisphereHigh latitudeIn the sea area, there is also the polar easterly current, which turns north after encountering land.All these currents form circulation systems on the ocean surface.In addition to the ocean surface circulation, there is also the ocean deep circulation.[1]
With global regularityAtmospheric motion, commonly referred to asatmospheric circulation。Large-areaVogueThe phenomenon that changes significantly with seasons is called monsoon.Monsoon circulationIt is also a part of the atmospheric circulation.The monsoon circulation in eastern Asia is the most typical.
The difference in thermal properties between land and sea leads to land and sea in winter and summerBarometric centerThe seasonal variation of is the main reason for the formation of monsoon circulation.The Pacific Ocean is the largest ocean in the world,EurasiaIt is the largest continent in the world, and East Asia lies between them. The temperature contrast and seasonal variation between sea and land are more significant than any other region.So,Differences in thermal properties between land and seaThe monsoon caused is most typical in East Asia, covering eastern ChinaKorean PeninsulaAnd Japan.
In winter, East Asia prevails from Mongolia -Siberian high（Asian High Voltage）The northerly wind at the front edge is cold, dry and strong. When the northerly wind is strong, it is a cold wave;In summer, East Asia prevails from the Pacific OceanSubtropical highThe southerly wind in the northwest is hot, humid and rainy.When the southerly flow meets the northerly flow, a large-scale rainfall belt will often be formed.
The difference in thermal properties between land and sea is an important reason for the formation of the monsoon, but not the only reason.Barometric zoneandWind bandThe seasonal movement of the location is also the reason for the formation of the monsoon.For example, Southwest China andIndian subcontinentBeltSouthwest monsoonIs the southern hemisphereSoutheast trade windIn summer, it moves northward across the equatorcoriolis force It is formed by deflecting to the right under the influence of.[1]
