Mechanical Engineering - Hydraulics and Fluid Mechanics - Discussion

I think answer is (velocity)2.
As change(pressure) = row*g*h.

h=flv2/2gd.
So change(pressure) directly proportional to v2.

Answer is right.

Loss of head = [32u*V(average)L]/r*g*d^2.

V(Average) = Average velocity.

For Laminar flow :

Loss of head = hF = [32*u*V(average)L]/r*g*d^2.

For turbulent flow:

HF = (flv^2)/(2*g*d).

In q they called loss of pressure head not friction head loss. So I think answer is right.

4flv2/2gd is a loss of pressure head and velocity is taken.

Whereas 32vl/d2 is a pressure drop and here average velocity is calculated.

Hence the answer given is contradictory.

Re is directly proportion to v.
f = 16/Re.
Hf = 4flv^2/2gd.
So, Hf is proportion to v.

Right answer because in pipe flow laminar 32u*v (average velocity) L/roh*g*d2.

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.