21. Ex 1. Two immiscible, incompressible, viscous fluids having same
densities but deferent viscosities are contained between two infinite
horizontal parallel plates, 2 m apart as shown below. The bottom plate
is fixed and the upper plate moves to the right with a constant velocity
of 3m/s. With the assumptions of Newtonian fluid, steady and fully
developed laminar flow zero pressure gradient in all directions , the
momentum equations simplify to
𝒅𝟐𝒖
𝒅𝒚𝟐 = 𝟎
If the dynamic viscosity of the lower fluid, m2, is
twice that of the upper fluid, m1, then the velocity
at the interface(round off to two decimal places) is
_____ m/s.
22.
23.
24. Ex 2. Kinematic viscosity of air at 20oC is given to be 1.6 x 10-5 m2/s. Its
kinematic viscosity at 70oC will be varying approximately
(a) 2.2 x 10-5 m2/s
(b) 1.6 x 10-5 m2/s
(c) 1.2 x 10-5 m2/s
(d) 3.2 x 10-5 m2/s
25.
26.
27.
28.
29.
30.
31. Ex 3. A solid shaft diameter of 100 mm, rotates at 100 rpm inside a
fixed sleeve bearing shown in the figure. Dynamic viscosity of oil is 1
poise.
Power lost due to viscosity in bearings is
(a) 4.3 Watt
(b) 8.6 Watt
(c) 17.3 Watt
(d) 0.215 Watt
32.
33.
34.
35.
36.
37. Ex 4. The rheological diagram depicting the relation between shear
stress and strain rate for different shear stress rate for different type
of fluids is shown in the figure below.
The most suitable relation for flow of tooth paste being squeezed out
of the tube is given by the curve
(a) P
(b) Q
(c) R
(d) S
38.
39. Ex 5. The following numerical values of kinematic viscosity
(centistoke) of an air at different temperatures recorded:
(1) 17 (2) 16 (3) 15 (4) 14
The temperatures recorded are 0oC, 20oC, 40oC and 60oC. Identify the
above values with the corresponding temperature
0oC 20oC 40oC 60oC
(a) 4 3 2 1
(b) 1 2 3 4
(c) 4 2 1 3
(d) 1 3 4 1
40.
41.
42.
43.
44.
45.
46.
47. Ex 6. A large tank with a nozzle attached contains three immiscible,
inviscid fluids shown. Assuming that the changes in h1, h2 and h3 are
negligible, the instantaneous discharge velocity is
(a) 𝟐𝒈𝒉𝟑 𝟏 +
𝝆𝟏𝒉𝟏
𝝆𝟑𝒉𝟑
+
𝝆𝟐𝒉𝟐
𝝆𝟑𝒉𝟑
(b) 𝟐𝒈(𝒉𝟏 + 𝒉𝟐 + 𝒉𝟑)
(c) 𝟐𝒈
𝝆𝟏𝒉𝟏+𝝆𝟐𝒉𝟐+𝝆𝟑𝒉𝟑
𝝆𝟏+𝝆𝟐+𝝆𝟑
(d) 𝟐𝒈
𝝆𝟑𝒉𝟐𝒉𝟑+𝝆𝟐𝒉𝟑𝒉𝟏+𝝆𝟑𝒉𝟏𝒉𝟐
𝝆𝟏𝒉𝟏+𝝆𝟐𝒉𝟐+𝝆𝟑𝒉𝟑
48.
49.
50.
51.
52.
53.
54. Ex 7. A hinged gate of length 5m, inclined at 30o with he horizontal
and with water mass on its left, is shown in figure below. Density of
water is 1000 kg/m3. The minimum mass of the gate in kg per unit
width (perpendicular to the plane of paper), required to keep it closed
(a) 5000
(b) 6600
(c) 7546
(d) 9623
55.
56. Ex 8. A thick layer oil of uniform thickness h, flows steadily down an
inclined plane as shown in figure. The oil has a density of 900 kg/m3.
The wall sear stress of a fluid volume element of thickness h = 1 mm
is
(a) 8.82 N/m2
(b) 4.41 N/m2
(c) 2.20 N/m2
(d) 20.2 N/m2
57.
58. Ex 9. Figure below shows four containers of oil. Rank them according
to the pressure at depth h, greatest first
(a) P > Q > R > S
(b) P < Q < R < S
(c) P > S > Q > R
(d) None
