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SPPU Civil Engineering (Semester 4)
Fluid Mechanics 1
December 2014
Total marks: --
Total time: --
INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary

Answer any one question from Q1 and Q2
1 (a) Explain the role of Fluid Mechanics and its practical applications for obtaining solution to practical flow problems.
3 M
1 (b) Explain with suitable examples application of viscosity in every day activity and design of engineering system.
3 M
1 (c) Differentiate between surface tension and capillarity. Give practical example of each. Derive the relation showing the capillary rise or fall depends on surface tension.
6 M

Answer any one question from Q3 and Q4
2 (a) A 10 mm glass tube is inserted into trough containing mercury. Find the capillary effect when the contact angle is:
i) 180° and
ii) 110°
Take surface tension of mercury in contact with air as 0.51 N/m.
3 M
2 (b) What is total pressure and centre of pressure? Derive the condition for total pressure on vertically immersed surface.
3 M
2 (c) Conduct a dimensional analysis by Buckingham π theorem and prove that the pressure drop in a venturimeter can be expressed by: $P= \rho V^2 f \left (\dfrac {d} {D} \right ).$ Where, P=pressure drop, V=velocity at inlet, ρ = fluid density, D and d diameter at inlet and throat.
6 M

3 (a) Explain:
i) Velocity potential function φ and
ii) Stream function ψ
and what are their properties. Show that equipotential and streamline meet orthogonally.
6 M
3 (b) Describe tht flow given by the expression below:
i) ψ=12y2+10,
ii) ψ=3s+12,
iii) ψ=5x-4y2.
6 M

4 (a) A venturimeter is to be fitted to a pipe of area 0.01767 m2. A maximum discharge of 5 m3 /min under a pressure of 4.5 m flows through the pipe. Find the diameter at the throat for no negative pressure at the throat.
6 M
4 (b) What is the difference between orifice and mouthpiece? Show that the discharge through an external mouthpiece is given by Q=0.855 a √2 gH, where a =area of mouthpiece and H=Height of liquid above mouthpiece.
6 M

Answer any one question from Q5 and Q6
5 (a) (i)
Write a short notes on :-

Rotameter
3 M
5 (a) (ii) Nozzlemeter
3 M
5 (b) Explain with sketch the development of boundary layer of flat plate. Explain the phenomenon of boundary layer separation and any one method to control it.
7 M

6 (a) Derive the expression for velocity distribution for generalized coquette flow (one plate stationary and other moving) and from it develop equation for discharge and shear stress.
7 M
6 (b) Derive expression for boundary layer thickness, boundary shear stress and friction drag in a turbulent boundary layer.
6 M

Answer any one question from Q7 and Q8
7 (a) What is turbulent flow and its characteristics ? Explain Isotropic turbulence, wall turbulence and free turbulence.
7 M
7 (b) What is roughening of pipe with age? How is roughness of old pipe determined? Explain Nikuradse? experiment with artificially roughened pipe and what are their significance?
6 M

8 (a) Derive the Darcy-Weishbach equation for friction loss in pipe.
6 M
8 (b) Three pipes of diameter 10 cm each, and having length 25 m, 50 m and 25 m are joined together in series. Water flows through this pipe at 2.15 m/s. The central pipe of length 50 m is replaced by 20 cm diameter pipe. The change in section due to replacement at both ends are sudden. Assuming friction factor f = 0.032 and Cc is 0.62, find the net saving in head.
7 M

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