Question

If water is flowing in a 1-inch diameter pipe with an average velocity of 3 m/s and the wall roughness is 400 microns, calculate the wall shear stress.

Answer 1

Shear stress is 50.63 Pascal

Step-by-step explanation:

As we know shear stress =
`(\rho V^2 f)/(8) \\`

Rho is the density

V is the velocity

f is the value from Moody's chart

We will know determine Reynolds number to determine the flow type and then the f value

`R_e = ( \rho*V*D)/(u)`

`R_e = (1000*3*0.0254)/(0.001) = 76200`

This is a turbulent flow and hence the roughness index is
`(E)/(D) = 0.0157`, From this we get f = 0.045

Now shear stress =
`(1000 * 3^2 * 0.045)/(8) = 50.63` Pa