Related Questions

Laminar flow of a Newtonion fluid ceases to exist, when the Reynolds number exceeds
A 4000
B 2100
C 1500
D 3000
During agitation of liquids, power consumption during laminar flow is not proportional to the
A Density of the liquid
B Viscosity of the liquid
C Cube of impeller diameters
D Square of rotational speed
For pipes, laminar flow occurs when Reynolds number is
A Less than 2000
B Between 2000 and 4000
C More than 4000
D Less than 4000
Power consumption during turbulent flow in agitation tank is proportional to the __________ of the liquid.
A Viscosity
B Thermal conductivity
C Surface tension
D Density
In convection heat transfer from hot flue gases to water tube, even though flow may be turbulent, a laminar flow region (boundary layer of film) exists close to the tube. The heat transfer through this film takes place by
A Convection
B Radiation
C Conduction
D Both convection and conduction
In case of hydraulically smooth pipe, the resistance to flow depends only on the Reynolds number, whereas for a hydraulically rough pipe, the resistance to flow is governed by the relative roughness. Two pipes are said to have the same hydraulic roughness, when they have equal values of
A Relative roughness
B Absolute roughness
C Friction co-efficient for flows at equal Reynold number
D All of the above
For laminar flow of a shear thinning liquid in a pipe, if the volumetric flow rate is doubled, the pressure gradient will increase by a factor of
A 2
B > 2
C $$\frac{1}{2}$$
Height of liquid in agitation tank is normally maintained equal to the tank diameter. However, if the tank is too tall and a large liquid hold up is desired, then two or more impellers mounted on the same shaft may be used. The clearance between the tank bottom and the bottom most impeller should be about (where, D = impeller diameter)
A 0.5 D
B D
C 1.5 D
D 2 D
Applying a pressure drop across a capillary results in a volumetric flow rate 'Q' under laminar flow conditions. The flow rate for the same pressure drop, in a capillary of the same length but half the radius is
A $$\frac{{\text{Q}}}{2}$$
B $$\frac{{\text{Q}}}{4}$$
C $$\frac{{\text{Q}}}{8}$$
D $$\frac{{\text{Q}}}{{16}}$$
The velocity at which the flow changes from laminar flow to turbulent flow is called
A Critical velocity
B Velocity of approach
C Sub-sonic velocity
D Super-sonic velocity

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