BEM2033 Fluid Mechanics 1 & EM211/EV201 Fluid Mechanics
Assignment 1
Jan-Apr 2020
Q1(a) Consider a viscometer with an inner cylinder which its radius is R1 and an outer cylinder
which its radius is R2. Inner cylinder is rotating with the speed of Ω (unit: rpm) in
clockwise direction. The length of the viscometer is 10 times larger than the radius of
outer cylinder. If the viscosity of the fluid is μ, express the equation for the torque of
the viscometer as a function of R1, R2, Ω and μ.
(10 marks)
(b)
Consider a rectangular gate which is immersed inside a water as shown in Figure Q1(c).
The width of the rectangular gate is 12 m. If the atmospheric pressure is ignored,
determine the minimum mass (m) needed to open the gate.
(10 marks)
Mass = ?
4m
50°
Rectangular gate
7m
Figure Q1(b)
Q2(a) A 10 cm diameter pipe is used to transport water from the lake to an empty tank which
is 10 m higher than the lake, as shown in Figure Q2(a). The tank has a volume of 12 m3
and shall be filled up within 1 hour. If the efficiency of the pump is 0.95 while the head
loss is 3.7 m, estimate the power required to be supplied to the pump.
(10 marks)
(b)
Consider a water sprinkler as in Figure Q2(b). The mass flow rate going into the
sprinkler from the base is 4.5 kg/s. The radius at the Outlet 1 and Outlet 2 is 4 cm and
7 cm respectively, with the water discharges to the atmosphere at the velocity of 0.75
m/s at Outlet 1. If the sprinkler is rotated at a speed of 150 rpm at clockwise direction,
determine the power produced by the sprinkler.
(10 marks)
Tank
Pump
10 m
Electric motor
60°
Figure Q2(a)
0.75 m/s
Outlet 1
0.6 m
Outlet 2
Base
0.3 m
0.8 m
Figure Q2(b)