# Chemical Engineering - Fluid Mechanics - Discussion

Discussion Forum : Fluid Mechanics - Section 1 (Q.No. 7)

7.

The head loss in turbulent flow in a pipe varies

Discussion:

10 comments Page 1 of 1.
Abhishek Kumar Singh said:
2 years ago

Head loss is V^2/2g.

Mandar Mahajan said:
6 years ago

Darcy Weisbach equation use.

Ap = 4flV^2/2D.

Ap = 4flV^2/2D.

(1)

A. Muthuraja said:
6 years ago

Answer B is correct.

Darcy-Weisbach equation, Hf=4fl(V^2)/(2gd) shows that Hf is directly proportional to velocity^2 and f for Turbulent Flow=0.079/Re: Here Re=pvd/μ.

As f is a dimensionless number (Even V term comes in Co-efficient of friction formula), Hf 4flV^2 is correct. We can also refer Dimensional and Model Analysis.

Option A is wrong (Hf is not various with V).

Option B is Correct (Hf is various with V^2).

Option C is Wrong(Hf is not inversely as the square of diameter).

Option D is Wrong (Hf is not inversely as the velocity).

Darcy-Weisbach equation, Hf=4fl(V^2)/(2gd) shows that Hf is directly proportional to velocity^2 and f for Turbulent Flow=0.079/Re: Here Re=pvd/μ.

As f is a dimensionless number (Even V term comes in Co-efficient of friction formula), Hf 4flV^2 is correct. We can also refer Dimensional and Model Analysis.

Option A is wrong (Hf is not various with V).

Option B is Correct (Hf is various with V^2).

Option C is Wrong(Hf is not inversely as the square of diameter).

Option D is Wrong (Hf is not inversely as the velocity).

(3)

Avinash kumar said:
7 years ago

One part of erg equation, which is Burke Plummer equation for turbulent gives the relation of head loss is firstly proportional to velocity squared and inversely proportional to diameter.

Riddhi said:
7 years ago

Anyone, Please explain this clearly.

PRASHANT said:
9 years ago

Because head loss is:

HL = (F)X(L/D)X(V2/2g).

Where,

HL = Total Head Loss.

F = Friction factor related to the roughness inside the pipe.

L = Length of the pipe.

D = Diameter of the pipe.

V = Average liquid velocity in the pipe.

2g = Two times the Universal Gravitation Constant (g=32.2 ft/sec).

HL = (F)X(L/D)X(V2/2g).

Where,

HL = Total Head Loss.

F = Friction factor related to the roughness inside the pipe.

L = Length of the pipe.

D = Diameter of the pipe.

V = Average liquid velocity in the pipe.

2g = Two times the Universal Gravitation Constant (g=32.2 ft/sec).

Muhammad Usman said:
10 years ago

Friction factor (f) = (g*D*Head loss) / 2*v^2*L.

This is general equation shows head loss is directly proportional to velocity ^2.

This is general equation shows head loss is directly proportional to velocity ^2.

Ravinder said:
1 decade ago

h = (4*f*(l/d)*v^2/2).

Vamsivardhan said:
1 decade ago

Pressure drop in a circular pipe in turbulent flow is proportional to velocity raised to the power of 1.7-1.9.

Nirnay said:
1 decade ago

h=4flv^2 / 2gd

for turbulent flow

f=0.079/Re^0.25

re=dvp/u

h directly propotional to v^1.75

nearly equal to 2

ans [B]

for turbulent flow

f=0.079/Re^0.25

re=dvp/u

h directly propotional to v^1.75

nearly equal to 2

ans [B]

(1)

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