Chemical Engineering - Chemical Engineering Basics - Discussion

Oh really. It should depend on length by looking at the formula we can say this. Also by logic, more the length more will be the friction. Please correct me if I am wrong. Thanks.

The correct option is "pipe length" and "mass flow rate of fluid".

The friction factor for fluid flow in a pipe depends on the pipe's roughness, fluid density and viscosity, and the flow conditions, such as the Reynolds number and the velocity of the fluid. However, it does not depend on the length of the pipe. This is because the friction factor is a property of the pipe and fluid system, and is independent of the distance over which the fluid flows.

Similarly, the friction factor is not directly dependent on the mass flow rate of the fluid. However, the mass flow rate can indirectly affect the friction factor by influencing the velocity and Reynolds number of the fluid.

In turbulent flow the friction formula also based length of the pipe. Then how should it be independent on the length? Please explain.

But as we increase pipe length friction will increase then how option A?

As F= 16/Nre.

And Nre= density*v*l/viscosity.

So it depend on length and not depend upon mass flow rate.

It depends on the length not depended on the mass flow rate.

@A.K.

The formula is hf = 4fLv2/2gD.

Which is made to find out the friction loss in the pipe, so the friction loss hf (frictional head) is dependent on length (how long we want to pump a fluid).

To find out friction factor value we prefer Analogies (Reynold or Colburn Analogy etc) which are fully based on dimensionless numbers(Prandtl and Stanton number) in those numbers you will never find any length factor.

On this basis I'm claiming the friction factor is independent of length.

Hope this answers your question.

When the flow of liquid then in pipe flow work below the ATM pressure hence friction formula says depend on length but not a roughness because roughness is different for different material.

@Muhammad.

Very well done, Thanks.

They asked f for the pipe.

f equals 16/re.
for a pipe Reynolds no. diameter is considered.
re for a flat plate length is considered.
So for a pipe, since diameter is considered to calculate Reynolds no.
Pipe length is not required.
Friction factor is independent of pipe length.