University Of Pune Question Paper
S.E. (Civil) (Semester – II) Examination, 2011
FLUID MECHANICS – I
(2003 Course)
Time : 3 Hours Max. Marks : 100
Instructions: i) Answer three question from Section I and three questions from
Section II.
ii) Answer to the two Sections should be written in separate
answer booklet.
iii) Neat diagrams must be drawn wherever necessary.
iv) Black figures to the right indicate full marks.
v) Your answer will be valued as a whole.
vi) Use of electronic pocket calculator is allowed.
vii) Assume suitable data if necessary.
SECTION – I
1. a) A skater weighing 800 N skates at 54 km/hr on ice at zero degree centigrade.
The average skating area supporting him is 10 cm2
and the effective dynamic
co-efficient of friction between the skates and ice ins 0.02. If there is actually
a thin film of water between the skates and the ice, determine its average
thickness. 9
b) What is surface Tension ? What is the unit of it ? Do you think it’s a line force ?
Derive the expression of pressure intensity for a droplet and sphere. 9
2. a) Derive the hydrostatic law showing pressure at any point below free surface is
given by p = Yh. 4
b) Draw the neat sketch of a Micro Manometer. 4
c) Derive the Continuity Equation in three dimensions in Cartesian co-ordinate. 8
3. a) What is flow net ? Prove that in any flow net the stream lines and equipotential
lines are orthogonal to each other. 4
b) Write in detail about Siphon along with necessary equations. 4
c) Derive the expression of Discharge for a ‘V’ notch. Is end contraction applicable
to ‘V’ notches ? Do you think velocity of approach can be considered in ‘V’
notch ? 8
4. a) Define orifice and state what is Vena Contracta ? Derive that coefficient of
velocity is equal to x/(4hy)0.5, where x and y are the co-ordinates and ‘h’ is
the head for the flow ? 8
b) Draw the neat sketch of a Venturimeter and show all the parts. 4
c) Draw the neat sketch of a Pitot Tube and state the importance of it. What do
you mean by stagnation point ? 4
5. a) A solid circular cylinder of radius ‘r’ and height ‘h’ is floating in water. The
specific gravity of the material of the cylinder is 0.64. Find the minimum ratio
r/h for which the cylinder will float in water with its axis vertical and it will be
just stable. 8
b) A plane flow has velocity components u = x/T, v = –y/T and w = 0, where T
is the constant having the dimension of time. Is the flow incompressible ? 8
SECTION – II
6. a) Write in details about Buckingham- π Theorem. 6
b) Discuss about Reynold’s Model Law. 6
c) The discharge over a hydraulic structure is a function of velocity, head of
water, depth and acceleration due to gravity. Find the ‘ π’ terms. How many
repeating variables will be there ? 6
7. a) Discuss in detail about the flow between two parallel plates, (both the plates
are at rest). Give your comment about the shear stresses at the lower and
upper plate. Find the relation between the maximum velocity and the average
velocity. 8
b) An oil of mass density 950 kg/m3
and dynamic viscosity 1.5 poise is pumped
through a 100 mm diameter pipe. The length of the pipe is 600 m. The flow
rate is 0.01 m3
/s.
Calculate the Reynolds Number of the flow. What would be the power input if
the overall efficiency of the pump is 75% ? 8
8. a) Velocity distribution in a turbulent flow of water through a 60 cm diameter
pipe is given by [v = 3 + (1/3) loge
y] where ‘V’ is the velocity at a distance ‘y’
normal to the pipe boundary. The shear stress at a point 12 cm from the
boundary is 25 N/cm2. Calculate the Prandtl’s Mixing Length coefficient. 8
b) Prove that for Turbulent flow the velocity distribution in rough pipes the
expression is
V/V * = 5.75 log10 (y/k) + 8.5
The symbols stand for their usual meanings. 8
9. a) u/U = Sin (Πy / 2δ ). Determine the energy thickness ** δ . 8
b) What do you mean by separation of Boundary Layer ? Describe it with the
help of a diagram. What do you mean by adverse pressure gradient ? Is it
good for fluid flow ? 8
10. a) Derive Hagen-Poiseuille Equation for laminar flow through a circular pipe.
Express it in terms of both discharge and average velocity. 8
b) Explain Prandtl’s Mixing length theory along with diagram. 4
c) Explain in detail about Moody’s diagram. Do you think for higher Reynolds
number the friction factor is not dependent on ‘Re’ ? Give your answer with
valid logic. 4
—————––––––———
S.E. (Civil) (Semester – II) Examination, 2011
FLUID MECHANICS – I
(2003 Course)
Time : 3 Hours Max. Marks : 100
Instructions: i) Answer three question from Section I and three questions from
Section II.
ii) Answer to the two Sections should be written in separate
answer booklet.
iii) Neat diagrams must be drawn wherever necessary.
iv) Black figures to the right indicate full marks.
v) Your answer will be valued as a whole.
vi) Use of electronic pocket calculator is allowed.
vii) Assume suitable data if necessary.
SECTION – I
1. a) A skater weighing 800 N skates at 54 km/hr on ice at zero degree centigrade.
The average skating area supporting him is 10 cm2
and the effective dynamic
co-efficient of friction between the skates and ice ins 0.02. If there is actually
a thin film of water between the skates and the ice, determine its average
thickness. 9
b) What is surface Tension ? What is the unit of it ? Do you think it’s a line force ?
Derive the expression of pressure intensity for a droplet and sphere. 9
2. a) Derive the hydrostatic law showing pressure at any point below free surface is
given by p = Yh. 4
b) Draw the neat sketch of a Micro Manometer. 4
c) Derive the Continuity Equation in three dimensions in Cartesian co-ordinate. 8
3. a) What is flow net ? Prove that in any flow net the stream lines and equipotential
lines are orthogonal to each other. 4
b) Write in detail about Siphon along with necessary equations. 4
c) Derive the expression of Discharge for a ‘V’ notch. Is end contraction applicable
to ‘V’ notches ? Do you think velocity of approach can be considered in ‘V’
notch ? 8
4. a) Define orifice and state what is Vena Contracta ? Derive that coefficient of
velocity is equal to x/(4hy)0.5, where x and y are the co-ordinates and ‘h’ is
the head for the flow ? 8
b) Draw the neat sketch of a Venturimeter and show all the parts. 4
c) Draw the neat sketch of a Pitot Tube and state the importance of it. What do
you mean by stagnation point ? 4
5. a) A solid circular cylinder of radius ‘r’ and height ‘h’ is floating in water. The
specific gravity of the material of the cylinder is 0.64. Find the minimum ratio
r/h for which the cylinder will float in water with its axis vertical and it will be
just stable. 8
b) A plane flow has velocity components u = x/T, v = –y/T and w = 0, where T
is the constant having the dimension of time. Is the flow incompressible ? 8
SECTION – II
6. a) Write in details about Buckingham- π Theorem. 6
b) Discuss about Reynold’s Model Law. 6
c) The discharge over a hydraulic structure is a function of velocity, head of
water, depth and acceleration due to gravity. Find the ‘ π’ terms. How many
repeating variables will be there ? 6
7. a) Discuss in detail about the flow between two parallel plates, (both the plates
are at rest). Give your comment about the shear stresses at the lower and
upper plate. Find the relation between the maximum velocity and the average
velocity. 8
b) An oil of mass density 950 kg/m3
and dynamic viscosity 1.5 poise is pumped
through a 100 mm diameter pipe. The length of the pipe is 600 m. The flow
rate is 0.01 m3
/s.
Calculate the Reynolds Number of the flow. What would be the power input if
the overall efficiency of the pump is 75% ? 8
8. a) Velocity distribution in a turbulent flow of water through a 60 cm diameter
pipe is given by [v = 3 + (1/3) loge
y] where ‘V’ is the velocity at a distance ‘y’
normal to the pipe boundary. The shear stress at a point 12 cm from the
boundary is 25 N/cm2. Calculate the Prandtl’s Mixing Length coefficient. 8
b) Prove that for Turbulent flow the velocity distribution in rough pipes the
expression is
V/V * = 5.75 log10 (y/k) + 8.5
The symbols stand for their usual meanings. 8
9. a) u/U = Sin (Πy / 2δ ). Determine the energy thickness ** δ . 8
b) What do you mean by separation of Boundary Layer ? Describe it with the
help of a diagram. What do you mean by adverse pressure gradient ? Is it
good for fluid flow ? 8
10. a) Derive Hagen-Poiseuille Equation for laminar flow through a circular pipe.
Express it in terms of both discharge and average velocity. 8
b) Explain Prandtl’s Mixing length theory along with diagram. 4
c) Explain in detail about Moody’s diagram. Do you think for higher Reynolds
number the friction factor is not dependent on ‘Re’ ? Give your answer with
valid logic. 4
—————––––––———
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