How to calculate the wetted perimeter

  • Thread starter theBEAST
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In summary, the wetted perimeter is the total length of the surface of a body of water that is in contact with the bed or banks. It is important to calculate it for determining flow rate and for engineering projects. The formula for a rectangular channel is 2*(width + height), and for a triangular channel it is (base length/2) + (height of the triangle * 2). Factors such as shape and roughness of the channel can also affect the wetted perimeter.
  • #1
theBEAST
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Homework Statement


So I have been taught that the wetted perimeter is the perimeter in which the surface is wet. So in the case for internal forced convection of a thick wall pipe I would have thought the perimeter would be 2*pi*r where r is the inner radius of the pipe. However, doing a bit of googling, this answer is clearly wrong as shown in the image below:
zyObkrl.png


Does anyone know why?
 
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  • #2
Yes. This is not a thick walled pipe calculation. It is a calculation of axial flow along an annular channel (between two concentric cylinders).

Chet
 

What is the wetted perimeter?

The wetted perimeter is the total length of the surface of a body of water that is in contact with the bed or banks of the water body.

Why is it important to calculate the wetted perimeter?

Calculating the wetted perimeter is important for determining the flow rate of a body of water, which is crucial for understanding and managing water resources. It is also used in engineering projects such as designing canals, culverts, and bridges.

How do you calculate the wetted perimeter of a rectangular channel?

The wetted perimeter of a rectangular channel is equal to the sum of the width and height of the channel. So, the formula for calculating the wetted perimeter is 2*(width + height).

What is the formula for calculating the wetted perimeter of a triangular channel?

The formula for calculating the wetted perimeter of a triangular channel is (base length/2) + (height of the triangle * 2). This formula takes into account the hypotenuse of the triangle as well as the two sides that make up the base.

Are there any other factors to consider when calculating the wetted perimeter?

Yes, the shape and roughness of the channel can also affect the wetted perimeter. For example, a channel with a rougher surface will have a larger wetted perimeter compared to a smooth channel of the same dimensions.

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