Download DHANALAKSHMI SRINIVASAN ENGINEERING COLLEGE

DHANALAKSHMI SRINIVASAN ENGINEERING COLLEGE
PERAMBALUR – 621 212
DEPARTMENT OF CIVIL ENGINEERING
Subject Code / Name
Class
Semester
: CE 1203 / MECHANICS OF FLUIDS
: II year
: III
Max. Marks: 100
Duration: 3 Hours
PART-A
(10 x 2 = 20)
Distinguish between ideal and real fluids.
State Newton’s law of viscosity.
What are streamline and path lines?
List out the properties of velocity potential function.
Why it is necessary to assume that the flow is steady before integrating Euler’s equation to
derive Bernoulli’s equation?
6. Where are Darcy Weisbach and Chezy’s formula used?
7. What is boundary layer? Give a sketch of a boundary layer region over a flat plate.
8. Define Displacement thickness.
9. State Buckingham’s π theorem.
10. State the demerits of a distorted model.
PART- B
(5 x 16 = 80)
11. An oil film of thickness 10mm is used for lubrication between the two square parallel plates
of size 0.9m x 0.9m each, in which the upper plate moves at 2 m/s required a force 100N to
maintain this speed. Determine (1)Dynamic viscosity of oil (2)Kinematic viscosity of oil, if
the specific gravity of the oil is 0.95.
OR
12. At a depth of 2 km in the ocean, the pressure is 82.4 x 10 3 kN/m2. Assume specific weight
at the surface as 10.055 kN/m3 and the bulk modulus of elasticity as 2.354 x 109N/m2 for
that pressure.
(a) What will be the change in specific volume?
(b) What will be the specific volume at that depth?
(c) What will be the specific weight at that depth?
13. Derive the continuity equation of differential form. Discuss whether the equation is valid for
a steady or unsteady flow, viscous or inviscid flow, compressible or incompressible flow.
OR
14. List out the various methods of construction of flow nets and give its advantages and
disadvantages.
15. Derive an expression for Hagen-Poiseuille’s equation for a laminar flow through a round
pipe.
OR
16. Derive an expression for Darcy-Weisbach formula to determine the head loss due to friction.
Give the expression for relation between friction factor ‘f’ and Reynold’s number ‘R e’ for
laminar and turbulent flow.
17. For the velocity profile in laminar boundary layer as (u/U)=3/2(y/δ) - 1/2(y/ δ) .Find the
thickness of the boundary layer and shear stress, 1.8m from the leading edge of a plate.
The plate is 2.5m long and 1.5m wide is placed in water, which is moving with a velocity of
15cm/sec. Find the drag on one side of the plate, if the viscosity of water is 0.01 poise.
OR
18. Two water reservoirs whose water elevations differ by 12m are connected by the following
horizontal compound pipe system starting from the high level reservoir.
L1 = 200mm, D1= 0.2m , f1 = 0.008 and
L1 = 500mm, D2 = 0.3m ,f2 = 0.006
Considering all head losses and assuming that all changes of section are abrupt, compute
the discharge through the system. Determine the equivalent length of a 0.25 m diameter
pipe, if minor losses are neglected and friction factors are assumed to be the same. Sketch
HGL and TEL.
19. Derive an expression showing the relationship between the torque and the variables
diameter, rotational speed, viscosity and density by Buckingham π method.
OR
20. A 7.2m high and 15m long spillway discharges 94 m3/s under a head of 2m. If a 1:9 scale
model of this spillway is to be constructed, determine the model to be used, model
dimensions, head at spillway and discharge in the model. If model experiences a force of
764 N, determine force on prototype.
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