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aChandra Venkataraman, 2020
Process Fluid Mechanics (CL 254) – Semester II, 2019-20a
Department of Chemical Engineering, Indian Institute of Technology – Bombay
Make-up 50 mark Exam: July 17, 2020, 11 am-1 pm
[Duration 2hrs; maximum marks 50; open book Fox, McDonald – F18; Good luck!
Instructions:
** SEND ALL ANSWER SCRIPT FILES AS ATTACHMENTS TO A SINGLE "REPLY" TO EMAIL IN WHICH YOU
GOT THE QUESTION PAPER; ELSE YOUR EXAM WILL NOT BE GRADED
** ANY CHEATING FROM AN INTERNET SOURCE OR EACH OTHER, WILL LEAD TO AWARD OF ZERO
MARKS, THEREFORE AWARD OF FR GRADE
** Name your pdf answer script CL254_MUE_yourrollno. If you set up EXCEL files, name them as
suggested in the questions below.]
Q1 Multiple choice questions (show all working – answers without working will receive ZERO marks;
2 marks each, total 20 marks)
i) The viscosity μ of a fluid primarily depends on:
a) density b) temperature c) pressure d) velocity e) surface tension
ii) Two parallel plates are separated by a 5-mm-thick layer of oil of specific gravity 0.80 and kinematic
viscosity 1.25E−4 m2/s. One moves at 4 m/s and the other is fixed. What is the average shear stress in
the oil?
a) 50 Pa b) 65 Pa c) 80 Pa d) 150 Pa e) 200 Pa
iii) A tank of water (SG = 1.0) has a gate in its vertical wall. The gate is 5 m high and 3 m wide and its
top edge is 2 m below the surface. What is the hydrostatic force on the gate?
a) 661 kN b) 870 kN c) 1011 kN d) 1440 kN e) 1890 kN
iv) Water exits from a converging nozzle, connected to a horizontal pipe, into atmospheric pressure of
101 kPa. If the exit velocity is V = 8 m/s and friction is neglected, what is the axial flange force
required to keep the nozzle attached to the pipe?
a) 5 N b) 11 N c) 17 N d) 22 N e) 36 N
v) A stream flows at velocity U past a body of length L and causes a force F on the
body. If F depends only upon U, L and fluid viscosity μ, then F must be proportional to:
a) ρUL/μ b) ρU2L2 c) μUL d) μU/L e) UL/μ
vi) Water at 20°C flows through a straight, smooth pipe at 0.06 m3/h. Calculate the approximate pipe
diameter for which transition to turbulence occurs:
a) 1 cm b) 1.45 cm c) 2.68 cm d) 3.55 cm e) 8.54 cm
vii) Oil (μ = 0.1 kg/(m⋅s), SG = 0.9) flows through a long, straight, smooth 5-cm dia
pipe at 14 m3/h. Calculate the approximate pressure drop per meter:
a) 10.2 kPa b) 2.5 kPa c) 1050 Pa d) 170 Pa e) 6 kPa
viii) Sea-level standard air at 4 m/s flows parallel to a thin flat plate. Estimate the
boundary-layer thickness at x = 60 cm from the leading edge:
a) 1.8 mm b) 3.2 mm c) 5.7 mm d) 7.5 mm e) 15.4 mm
ix) A dust particle of density 2600 kg/m3, satisfies Stokes drag law, and
settles at 1.5 mm/s in air at 20°C and 1 atm. What is its approximate diameter?
a) 2.6 μ m b) 4.4 μ m c) 8.3 μ m d) 12.8 μ m e) 20.3 μ m
