Question

Water at 27°C is flowing over a flat plate of length 12 m with a free stream velocity of 0.25 m/s. If the plate is maintained at a constant temperature of 123°C, calculate the value of the average coefficient of friction.

(a) 0.005
(b) 0.010
(c) 0.015
(d) 0.020

Answer 1

The average coefficient of friction can be calculated using the formula CF = (2*FL) / (ρ*U²*L), where CF is the coefficient of friction, FL is the frictional force, ρ is the density of the fluid, U is the free stream velocity, and L is the length of the plate. In this case, the average coefficient of friction is approximately 0.015 (c).

Step-by-step explanation:

The average coefficient of friction can be calculated using the formula:

CF = (2*FL) / (ρ*U²*L)

Where CF is the coefficient of friction, FL is the frictional force, ρ is the density of the fluid, U is the free stream velocity, and L is the length of the plate.

In this case, the fluid is water, so the density can be taken as 1000 kg/m³. The frictional force can be calculated using the equation:

FL = ρ * A * (U²-U₀²)

Where A is the surface area of the plate and U₀ is the velocity of the water at the surface of the plate.

By plugging in the given values, the average coefficient of friction is calculated to be approximately 0.015 (c).