Mechanical Engineering - Hydraulics and Fluid Mechanics - Discussion

What is weir?

Weir is a barrier built across river to direct flow of water.

Crest means?

Crest is the height of flow above the weir.

Is it based on Buoyancy effect?

Any one can send link about this topic?

Crest is the bottom edge of weir over which the water flows.

Please justify the answer clearly.

A broad-crested weir is a flat-crested structure, with a long crest compared to the flow thickness. When the crest is "broad", the streamlines become parallel to the crest invert and the pressure distribution above the crest is hydrostatic. The hydraulic characteristics of broad-crested weirs were studied during the 19th and 20th centuries. Practical experience showed that the weir overflow is affected by the upstream flow conditions and the weir.

An obstruction that allows the liquid to flow over it is called a weir.

Crest is a horizontal top edge of weir on which the liquid flows.

Broad crested weir: A broad crested weir is a rectangular block of width (or length) , w and height, p and w>p. As its name implies that this type of weir has a broad (large width) crest. In broad crested weir the width of the crest of the weir is more than half the height of water above the weir crest.