Narrow tube effect: Is the wind getting bigger or smaller?

Narrow tube effect, when air flows into the canyon from the open area, the air density is compressed, the wind speed increases, and the air will flow through the canyon at an accelerated speed. When it flows out of the canyon, the air speed will slow down again. The influence of this canyon topography on airflow is called "canyon effect". The wind with increased canyon effect is usually called canyon wind or through flow.

Narrow tube effect-main principle

When the liquid flows in the pipe, the speed increases when it passes through the narrow place. When air flows through the narrow terrain on the ground, similar to the flow of liquid in a pipeline, the speed will also increase and the density will also increase because of the compressibility of gas. The tuyeres in many mountain areas and the topographic precipitation in many places on the earth are closely related to the narrow terrain through which the airflow passes. The wind increased by the narrow tube effect is called canyon wind or through flow.

Narrow tube effect-cause

1, canyon topography, natural canyon topography will have an impact on wind speed, resulting in a narrow tube effect.

2. Tall buildings cause a narrow pipe effect, just as the wind in the canyon is always stronger than that in the plain, and the narrow area between tall buildings in the city is also very windy, which is easy to cause disasters. In some buildings, the instantaneous wind force in narrow areas is so strong that the driving cars will shake. Urban "canyon wind" is a new problem faced by major cities, and relevant international organizations have included it in the 20 major urban disasters faced by major cities.

Narrow tube effect-influencing factors

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Black wind

The detection of relevant meteorological departments shows that when there is a strong wind of magnitude 6 or 7 in the city, the instantaneous wind force between tall buildings can reach 12 due to the narrow tube effect, and billboards and some courtyard walls are hard to resist.

The power of narrow tube effect is closely related to the number, spacing and location of high-rise buildings in a city. The more high-rise buildings there are, the greater the volume and the closer the spacing, and the greater the probability of "narrow tube effect", and vice versa.

First of all, the influence of weather system, such as cold wave, sandstorm and typhoon, will cause large-scale and large-scale airflow, but this will only lead to strong wind, but it will not cause such severe damage. The second condition is the local topography. The accident happened in the north and south valleys of Tianshan Mountain. When the strong wind passes through this terrain, that is, the tuyere, the wind force will be rapidly amplified by the "narrow tube effect" and multiplied, and its destructive power is amazing.