JNTU, B-Tech,I-Semester, Fluid Mechanics , November 2008


JNTU, B.Tech,I-Semester

Fluid Mechanics

 November 2008

(Civil Engineering)




1. (a) What are the density, Specific weight, Specific volume and Kinematic viscosity

of a liquid in S.I. units, if its relative density is 0.804 and dynamic viscosity is

9.8 poise. Express your answer in C.G.S. units also.

(b) A liquid occupying a volume of 0.225 m3, has a weight of 1.89 kN. What are

its density, relative density, Specific weight and Specific volume?


2. (a) A gauge on the suction side of a pump shows a negative pressure of 0.285 bar.

Express this pressure in terms of

i. pressure intensity in kPa

ii. N/m2absolute

iii. m of water gauge. Take atmospheric pressure as 76 cm of mercury and

relative density of mercury as 13.6.

(b) A cylindrical tank of 3 m height and 5-cm2 cross-sectional area is filled with

water up to a height of 2 m and remaining with oil of specific gravity 0.8.The

vessel is open to atmosphere. Calculate:

i. pressure intensity at the interface,

ii. absolute and gauge pressure on the base of the tank in terms of water

head, oil head and N/m2.Also workout the net force experienced by the

base of the tank. Take atmospheric pressure as 1.0132 bar.


3. (a) Explain one, two and three dimensional flows.

(b) If ?= 3xy, find x and y components of velocity at (1,3) and (3,3). Determine

the discharge passing between streamlines passing through these points.


4. (a) A tank has a nozzle of exit diameter D1 at a depth H1 below the free surface.

At the side opposite to that of nozzle 1, another nozzle is proposed at a depth

H1/2. What should be the diameter of the second nozzle D2, interms of D1

so that the net horizontal force on the tank is zero?

(b) In a pump the suction and delivery pipes are of the same size and are at the

same level. At a given discharge the loss of head between a point A on the

suction side and a point B on the delivery side is 3.0 m. If the pressure at

point B is 120 KPa and the head developed by the pump is 10 m, find the

pressure at point A.


5. (a) Define the terms drag and lift. Derive mathematical expressions for drag and lift.

(b) The air is flowing over a cylinder of diameter 10cm and of infinite length with

a velocity of 15 cm/sec. Find the total drag, shear drag and pressure drag

on 1m length of the cylinder if the total drag coefficient is 1.5 and shear drag

coefficient is 0.25. The density of air is given as 1.25 kg/m3.


6. (a) Prove that the velocity distribution for viscous flow between two parallel plates

when both plates are fixed across a section is parabolic in nature. Also prove

that maximum velocity is equal to half the average velocity.

(b) Water is flowing between two large parallel plates which are 2mm apart. De-

termine maximum velocity, the pressure drop per unit length and shear stress

at walls of the plate if the average velocity is 0.4 m/sec. Take viscosity of

water as 0.01 poise.


7. A liquid of specific gravity 0.88 and absolute viscosity 6.533 X 10?4N.s/m2 flows

through a pipe of diameter 0.15 m at the rate of 60 liters per second. If the loss of

head in 100m, length of pipe is 4.56, find whether the pipe is rough or smooth.


8. A venturimeter having inlet diameter 100 mm and throat diameter 25 mm is fitted

in a vertical pipe, throat is 0.3 m below the inlet, for measuring the flow of petrol

of specific gravity 0.78. Pressure gauges are fitted at inlet and throat. Taking loss

of head between inlet and throat as 36 times the velocity head at inlet, find cd of

the meter and the discharge when the inlet gauge reads 274.68 KN/m2.


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