SAME FLUID 4. SAME FLUID FLOW PATTERN SELECT THE CORRECT ANSWER USI...
3. Same fluid
4. Same fluid flow pattern
Select the correct answer using the code given below:
(a) 1 only
(b) 1 and 2
(c) 3 and 4
(d) 4 only
IES-28. The average Nusselt number in laminar natural convection from a
vertical wall at 180°C with still air at 20°C is found to be 48. If the wall
temperature becomes 30°C, all other parameters remaining same, the
average Nusselt number will be:
[IES-2002]
(a) 8
(b) 16
(c) 24
(d) 32
IES-29. For fully-developed turbulent flow in a pipe with heating, the Nusselt
number N
u
, varies with Reynolds number R
e
and Prandtl number P
r
as
[IES-2003]
(a)
R P
e
0.5
r
1
3
(b)
R P
e
0.8
r
0.2
(c)
R P
e
0.8
r
0.4
(d)
R P
e
0.8
r
0.3
IES-30. For laminar flow over a flat plate, the local heat transfer coefficient 'h
x
'
varies as x
-1/2
, where x is the distance from the leading edge (x = 0) of
the plate. The ratio of the average coefficient 'h
a
' between the leading
Page 46 of 97
edge and some location 'A' at x = x on the plate to the local heat transfer
coefficient 'h
x
' at A is:
[IES-1999]
(a) 1
(b) 2
(c) 4
(d) 8
IES-31. When there is a flow of fluid over a flat plate of length 'L', the average
heat transfer coefficient is given by (Nu
x
= Local Nusselt number; other
symbols have the usual meaning)
[IES-1997]
L
k
Nu dx
1
L
∫
(b)
dx
d
( )
h
x
(c)
(a)
x
h dx
x
L
∫
L
∫
(d)
0
IES-32. In the case of turbulent flow through a horizontal isothermal cylinder
of diameter 'D', free convection heat transfer coefficient from the
cylinder will:
[IES-1997]
(a) Be independent of diameter
(b) Vary as D
3/4
(c)
Vary
as
D
1/4
(d) Vary as D
1/2
IES-33. Match List-I (Dimensionless quantity) with List-II (Application) and
select the correct answer using the codes given below the lists:
List-I
List-II
[IES-1993]
A. Stanton number
1. Natural convection for ideal gases
B. Grashof number
2. Mass transfer
C. Peclet number
3. Forced convection
D.
Schmidt number
4.
Forced convection for small
Prandtl number
Codes: A
B
C
D
A
B
C
D
(a)
2
4
3
1
(b)
3
1
4
2
(c)
3
4
1
2
(d)
2
1
3
4
IES-34. Assertion (A): All analyses of heat transfer in turbulent flow must
eventually rely on experimental data.
[IES-2000]
Reason (R): The eddy properties vary across the boundary layer and no
adequate theory is available to predict their behaviour.
(a) Both A and R are individually true and R is the correct explanation of A
(b) Both A and R are individually true but R is not the correct explanation of A
(c) A is true but R is false
(d) A is false but R is true
Page 47 of 97
IES-35.
Match the velocity profiles labelled A, B, C and D with the following
situations: [IES-1998]