Fluid Mechanics

371.Permanent pressure loss in a well designed Venturimeter is about _________ percent of the venturi differential.

1. 1
2. 10
3. 30
4. 50

372.Pick out the correct statement pertaining to the flow through a converging-diverging tube.

1. The value of Mach number is always unity at the throat
2. No shock wave develops in the tube when the Mach number at exit is greater than unity
3. Throughout the converging portion of the tube, the density increases in the downstream direction
4. None of these

373.Pick out the correct statement pertaining to transition/ entrance length in fluid flow.

1. The length of entrance region of pipe, in which full development of fluid flow takes place such that velocity profile does not change downstream, is called the transition length
2. Transition length for laminar flow of Newtonian fluids in a pipe of diameter 'd' is equal to 0.05. D.NR_e
3. Transition length for turbulent flow of Newtonian fluids in a smooth pipe of diameter 'd' is equal to 50 D
4. All (A), (B) and (C)

374.Pick out the correct statement pertaining to Venturimeter.

1. A Venturimeter with a fixed pressure drop discharges more, when the flow is vertically downward, than when the flow is vertically upward
2. The co-efficient of contraction of a Venturimeter is always unity
3. For a fixed pressure drop, the discharge of a gas through a Venturimeter is greater, when compressibility is taken into account, than when it is neglected
4. None of these

375.Pick out the correct statement.

1. Human blood is a Newtonian fluid
2. A Newtonian fluid obeys Newton's law of cooling
3. For a non-Newtonian fluid, a straight line passes through the origin in a plot between shear stress and shear gradient
4. Thin lubricating oil is an example of a non-Newtonian fluid

376.Pick out the Hagen-Poiseuille‟s equation.

1. Δp/ρ = 4f (L/D) (v²/2g_c)
2. Δp = 32 (μLV/g_c. d²)
3. Δp/L = 150 [(1 - ε)/ε3]. (μ.V₀²/g2cD)
4. Δp/L = 1.75 [(1 - ε)/ε3]. (ρV₀²/g_cD_p)

377.Pick out the wrong statement about a streamline.

1. It is always parallel to the main direction of the fluid flow
2. It is a line across which there is no flow and it is equivalent to a rigid boundary
3. Streamlines intersect at isolated point of zero velocity and infinite velocity
4. The fluid lying between any two streamlines can be considered to be in isolation and the streamline spacing varies inversely as the velocity

378.Pick out the wrong statement about cavitation.

1. Sudden reduction of pressure in a fluid flow system caused by flow separation, vortex formation or abrupt closing of valve leads to cavitation
2. Cavitation may be caused due to boiling of liquid by decreasing the pressure resulting in formation & collapse of vapor cavities
3. Cavitation begins at higher static pressure and lower velocity in larger diameter pipelines resulting in audible noise
4. Large scale cavitation cannot damage pipeline, restrict fluid flow and damage steam turbine blades

379.Pick out the wrong statement pertaining to fluid flow.

1. The ratio of average velocity to the maximum velocity for turbulent flow of Newtonian fluid in circular pipes is 0.5
2. The Newtonian fluid velocity in a circular pipe flow is maximum at the centre of the pipe
3. Navier-Stokes equation is applicable to the analysis of viscous flows
4. Hagen-Poiseuille equation is applicable to the laminar flow of Newtonian fluids

380.Pick out the wrong statement.

1. A fluid mass is free from shearing forces, when it is made to rotate with a uniform velocity
2. Newton's law of viscosity is not applicable to the turbulent flow of fluid with linear velocity distribution
3. Laminar flow of viscous liquids is involved in the lubrication of various types of bearings
4. Rise of water in capillary tubes reduces with the increasing diameter of capillary tubes