Civil Engineering - Irrigation - Discussion

The word siphon is used to refer to a wide variety of devices that involve the flow of liquids through tubes. In a narrower sense, the word refers particularly to a tube in an inverted 'U' shape, which causes a liquid to flow upward, above the surface of a reservoir, with no pump, but powered by the fall of the liquid as it flows down the tube under the pull of gravity, then discharging at a level lower than the surface of the reservoir from which it came.

Answer B is correct.

Answer is D is correct. Negative pressure.

Pipe flow is the correct answer.

Which one is the correct answer? Please explain.

The correct Answer is B.

It's pipe flow. Only water head is involved in transporting water from one side to another.

Atmospheric pressure on both inlet and outlet is equal. Negative pressure only works in inverted you shaped syphon. Critical velocity won't happen as the section of flow is changing direction not it's size.

I think it's negative pressure.

Siphon action means the flow of water under vacuum without any external energy. Thus this vacuum pressure is below or at absolute pressure. Thus below absolute pressure, it is vacuum pressure which we take negative pressure. Therefore, syphon action occurs under a negative pressure gradient.

The correct answer is option (D) under negative pressure.

When the canal is flowing under the drainage in the syphonic action, there is no open space between canal water and drainage bed.

Because of having contracted flow, the canal flows under pressure, and we know that fluid flows in pressure in the pipe flow.

Now please can someone explain me, at the time of syphonic action in canal water and getting this much high pressure during flow, how can the pressure be negative?