Mechanical Engineering - Hydraulics and Fluid Mechanics - Discussion

For Laminar flow
hL =(32μLVavg)/(ρgD^2 ) -------------> (i)

For Laminar or turbulent flows, circular or noncircular pipes, smooth or rough surfaces, horizontal or inclined pipes.
hL =f L/D (Vavg^2)/2g -------------> (ii)

Now, value of friction factor, f is different for different flows
In case of laminar flow
friction factor, f = 64μ/(ρDVavg )=64/Re ------------> (iii)

By putting the value of friction factor (laminar given above) in equation (ii) we will get the equation (i) which conclude that loss of pressure head (hL) is directly proportional to velocity, Vavg (Not V^2).

It is according to Hagen Poisennus Law.

Yeah, the answer is right del. p =32mu vl /r^2.

Why so confusing. It's simply asking head loss and is directly proportional to the square of the velocity that's it.

Laminar directly proportional to velocity (hagen poisellea eqn} and in case turbulent proportional to square of velocity (darcy formula).