## 100 TOP FLUID MECHANICS Interview Questions and Answers <—-CLICK HERE

71. The value of friction factor ‘f’ for smooth pipes for Reynolds number 106 is approximately equal to

a) 0.1

b) 0.01

c) 0.001

d) 0.0001

Ans: b

72. For laminar flow in a pipe of circular cross-section, the Darcy’s friction factor f is

a) directly proportional to Reynolds number and independent of pipe wall roughness

b) directly proportional to pipe wall roughness and independent of Reynolds number

c) inversely proportional to Reynolds number and indpendent of pipe wall roughness

d) inversely proportional to Reynolds number and directly proportional to pipe wall roughness

Ans: c

73. Separation of flow occurs when

a) the pressure intensity reaches a minimum

b) the cross-section of a channel is reduced

c) the boundary layer comes to rest

d) all of the above

Ans: c

74. The ratio of average velocity to maximum velocity for steady laminar flow in circular pipes is

a) 1/2

b) 2/3

c) 3/2

d) 2

Ans: a

75. The distance from pipe boundary, at which the turbulent shear stress is one-third die wall shear stress, is

a) 1/3 R

b) 1/2 R

c) 2/3 R

d) 3/4R

where R is the radius of pipe.

Ans: a