The value of critical Reynolds number for pipe flow is (A) 1,300(B) 10,000 (C) 100,000 (D) None of these

The value of critical Reynolds number for pipe flow is
(A) 1,300
(B) 10,000
(C) 100,000
(D) None of these
by

1 Answer

Answer :

(A) 1,300
by

Related questions

Reynolds number of a fluid flowing in a circular pipe is 10,000. What will be the Reynolds number when the fluid velocity is decreased by 30% & the pipe diameter is increased by 30%? (A) 9,100 (B) 13,000 (C) 7,000 (D) 2,550

Description : Reynolds number of a fluid flowing in a circular pipe is 10,000. What will be the Reynolds number when the fluid velocity is decreased by 30% & the pipe diameter is increased by 30%? (A) 9,100 (B) 13,000 (C) 7,000 (D) 2,550

Last Answer : (A) 9,100

Reynolds number for flow of water at room temperature through 2 cm dia pipe at an average velocity of 5 cm/sec is around (A) 2000 (B) 10(C) 100 (D) 1000 Answer:

Description : Reynolds number for flow of water at room temperature through 2 cm dia pipe at an average velocity of 5 cm/sec is around (A) 2000 (B) 10 (C) 100 (D) 1000 Answer:

Last Answer : (D) 1000

Critical value of the __________ number governs the transition from laminar to turbulent flow in free convection heat transfer. (A) Grashoff (B) Reynolds (C) Both 'a' & 'b' (D) Prandtl & Grashoff

Description : Critical value of the __________ number governs the transition from laminar to turbulent flow in free convection heat transfer. (A) Grashoff (B) Reynolds (C) Both 'a' & 'b' (D) Prandtl & Grashoff

Last Answer : (D) Prandtl & Grashoff

Laminar flow region is said to exist during agitation of a liquid in an agitator, when the value of Reynolds number is (A) > 10 (B) < 10 (C) > 100 (D) < 100

Description : Laminar flow region is said to exist during agitation of a liquid in an agitator, when the value of Reynolds number is (A) > 10 (B) < 10 (C) > 100 (D) < 100

Last Answer : (B) < 10

The Sieder-Tate correlation for heat transfer in turbulent flow in pipe gives Nu α Re 0.8 , where, Nu is the Nusselt number and Re is the Reynolds number for the flow. Assuming that this relation is valid, the heat transfer co-efficient varies with the pipe diameter (D) as (A) D-1.8 (B) D-0.2 (C) D0.2 (D) D1.8

Description : The Sieder-Tate correlation for heat transfer in turbulent flow in pipe gives Nu α Re 0.8 , where, Nu is the Nusselt number and Re is the Reynolds number for the flow. Assuming that this relation is valid, the heat transfer co-efficient ... pipe diameter (D) as (A) D-1.8 (B) D-0.2 (C) D0.2 (D) D1.8

Last Answer : (B) D-0.2

The friction factor for turbulent flow in a hydraulically smooth pipe (A) Depends only on Reynolds number (B) Does not depend on Reynolds number (C) Depends on the roughness (D) None of these

Description : The friction factor for turbulent flow in a hydraulically smooth pipe (A) Depends only on Reynolds number (B) Does not depend on Reynolds number (C) Depends on the roughness (D) None of these

Last Answer : (A) Depends only on Reynolds number

When the pipe Reynold's number is 6000, the flow is generally (A) Viscous(B) Laminar(C) Turbulent(D) Transition

Description : When the pipe Reynold's number is 6000, the flow is generally (A) Viscous (B) Laminar (C) Turbulent (D) Transition

Last Answer : (C) Turbulent

In turbulent flow, a rough pipe has the same friction factor as a smooth pipe (A) In the zone of complete turbulence (B) When the roughness projections are much smaller than the thickness of the laminar film (C) Everywhere in the transition zone (D) When the friction factor is independent of the Reynold's number

Description : In turbulent flow, a rough pipe has the same friction factor as a smooth pipe (A) In the zone of complete turbulence (B) When the roughness projections are much smaller than the thickness of ... ) Everywhere in the transition zone (D) When the friction factor is independent of the Reynold's number

Last Answer : (B) When the roughness projections are much smaller than the thickness of the laminar film

Reynolds number for water flow through a tube of I.D. 5 cm is 1500. If a liquid of 5 centipoise viscosity and 0.8 specific gravity flows in the same pipe at the same velocity, then the pressure drop will (A) Increase (B) Decrease (C) Remain same (D) Data insufficient to predict pressure drop

Description : Reynolds number for water flow through a tube of I.D. 5 cm is 1500. If a liquid of 5 centipoise viscosity and 0.8 specific gravity flows in the same pipe at the same velocity, then the pressure drop will (A) Increase (B) Decrease (C) Remain same (D) Data insufficient to predict pressure drop

Last Answer : (A) Increase

Pick out the wrong statement: (A) Greater is the kinematic viscosity of the liquid, greater is the thickness of the boundary layer (B) Blowers develop a maximum pressure of 2 atmospheres (C) Friction losses in pipe fittings are generally expressed in terms of velocity heads (D) Fanning friction factor in case of turbulent flow of liquids in pipe depends upon relative roughness & Reynolds number

Description : Pick out the wrong statement: (A) Greater is the kinematic viscosity of the liquid, greater is the thickness of the boundary layer (B) Blowers develop a maximum pressure of 2 atmospheres ( ... factor in case of turbulent flow of liquids in pipe depends upon relative roughness & Reynolds number

Last Answer : (C) Friction losses in pipe fittings are generally expressed in terms of velocity heads

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 (A), (B) & (C)

Description : 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 ... co-efficient for flows at equal Reynold number (D) All (A), (B) & (C)

Last Answer : (C) Friction co-efficient for flows at equal Reynold number

Fanning friction factor for laminar flow of fluid in a circular pipe is (A) Not a function of the roughness of pipe wall (B) Inversely proportional to Reynolds number (C) Both (A) & (B) (D) Neither (A) nor (B)

Description : Fanning friction factor for laminar flow of fluid in a circular pipe is (A) Not a function of the roughness of pipe wall (B) Inversely proportional to Reynolds number (C) Both (A) & (B) (D) Neither (A) nor (B)

Last Answer : (C) Both (A) & (B)

. In case of turbulent flow of fluid through a circular pipe, the (A) Mean flow velocity is about 0.5 times the maximum velocity (B) Velocity profile becomes flatter and flatter with increasing Reynolds number (C) Point of maximum instability exists at a distance of 2r/3 from the pipe wall (r = pipe radius) (D) Skin friction drag, shear stresses, random orientation of fluid particles and slope of velocity profile at the wall are more

Description : . In case of turbulent flow of fluid through a circular pipe, the (A) Mean flow velocity is about 0.5 times the maximum velocity (B) Velocity profile becomes flatter and flatter with ... , shear stresses, random orientation of fluid particles and slope of velocity profile at the wall are more

Last Answer : (D) Skin friction drag, shear stresses, random orientation of fluid particles and slope of velocity profile at the wall are more

__________ number determines whether the fluid flow in an open channel is supercritical, critical or sub-critical. (A) Mach (B) Reynolds (C) Froude (D) Weber

Description : __________ number determines whether the fluid flow in an open channel is supercritical, critical or sub-critical. (A) Mach (B) Reynolds (C) Froude (D) Weber

Last Answer : (C) Froude

The co-efficient of discharge of an orificemeter is a function of (A) Reynolds number at the orifice (B) Ratio of orifice dia to pipe dia (C) Both (A) and (B) (D) None of the above parameters, and has a constant value of 0.61

Description : The co-efficient of discharge of an orificemeter is a function of (A) Reynolds number at the orifice (B) Ratio of orifice dia to pipe dia (C) Both (A) and (B) (D) None of the above parameters, and has a constant value of 0.61

Last Answer : (C) Both (A) and (B)

Transition from laminar to turbulent zone in free convection heat transfer is governed by the critical value of (A) Grashoff number (B) Grashoff number & Reynolds number (C) Reynolds number (D) Grashoff number & Prandtl number

Description : Transition from laminar to turbulent zone in free convection heat transfer is governed by the critical value of (A) Grashoff number (B) Grashoff number & Reynolds number (C) Reynolds number (D) Grashoff number & Prandtl number

Last Answer : Option D

For an ideal fluid flow, Reynolds number is (A) 2100 (B) 100 (C) 0 (D) ∞

Description : For an ideal fluid flow, Reynolds number is (A) 2100 (B) 100 (C) 0 (D) ∞

Last Answer : (D) ∞

The friction factor is (A) Always inversely proportional to the Reynolds number (B) Not dimensionless (C) Not dependent on the roughness of the pipe (D) None of these

Description : The friction factor is (A) Always inversely proportional to the Reynolds number (B) Not dimensionless (C) Not dependent on the roughness of the pipe (D) None of these

Last Answer : (D) None of these

The discharge co-efficient for an orifice meter does not depend upon the (A) Pipe length (B) Ratio of pipe diameter to orifice diameter (C) Type of orifice & the Reynolds number (D) Pipe diameter

Description : The discharge co-efficient for an orifice meter does not depend upon the (A) Pipe length (B) Ratio of pipe diameter to orifice diameter (C) Type of orifice & the Reynolds number (D) Pipe diameter

Last Answer : (A) Pipe length

A pipe is defined as 'hydraulically smooth', if the friction factor (A) Is not a function of Reynolds number (B) For a given Reynolds number remains constant even on further smoothening of the pipe (C) Is zero irrespective of the Reynolds number (D) None of these

Description : A pipe is defined as 'hydraulically smooth', if the friction factor (A) Is not a function of Reynolds number (B) For a given Reynolds number remains constant even on further smoothening of the pipe (C) Is zero irrespective of the Reynolds number (D) None of these

Last Answer : (B) For a given Reynolds number remains constant even on further smoothening of the pipe

For a given Reynolds number, in a hydraulically smooth pipe, further smoothening __________ the friction factor. (A) Brings about no further reduction of (B) Increases (C) Decreases (D) None of these

Description : For a given Reynolds number, in a hydraulically smooth pipe, further smoothening __________ the friction factor. (A) Brings about no further reduction of (B) Increases (C) Decreases (D) None of these

Last Answer : (A) Brings about no further reduction of

. Equivalent length of a pipe fitting is (A) Dependent on Reynolds number (B) Independent of Reynolds number (C) Dependent on the length of the pipe (D) None of these

Description : . Equivalent length of a pipe fitting is (A) Dependent on Reynolds number (B) Independent of Reynolds number (C) Dependent on the length of the pipe (D) None of these

Last Answer : (A) Dependent on Reynolds number

Froude number is not a factor (A) For Reynolds number greater than 300 (B) When there is no vortex formation (C) For unbaffled tank (D) None of these

Description : Froude number is not a factor (A) For Reynolds number greater than 300 (B) When there is no vortex formation (C) For unbaffled tank (D) None of these

Last Answer : (B) When there is no vortex formation

Heat transfer co-efficient equation for forced convection, Nu = 0.023 Re 0.8 . Pr n , is not valid, if the value of (A) n = 0.4 is used for heating (B) n = 0.3 is used for cooling (C) Reynolds number for the flow involved is > 10000 (D) Reynolds number for the flow involved is < 2100

Description : Heat transfer co-efficient equation for forced convection, Nu = 0.023 Re 0.8 . Pr n , is not valid, if the value of (A) n = 0.4 is used for heating (B) n = 0.3 is used for cooling (C) Reynolds number for the flow involved is > 10000 (D) Reynolds number for the flow involved is < 2100

Last Answer : (D) Reynolds number for the flow involved is < 2100

As the velocity V and thus the Reynolds number of a flow past a sphere increases from very low value, the drag force for Re << 1 (A) Increases linearly with V (B) Decreases linearly with V (C) Decreases as V2 (D) None of these

Description : As the velocity V and thus the Reynolds number of a flow past a sphere increases from very low value, the drag force for Re

Last Answer : (A) Increases linearly with V

Two fluids are flowing through two similar pipes of the same diameter. The Reynold's number is same. For the same flow rate if the viscosity of a fluid is reduced to half the value of the first fluid, the pressure drop will (A) Increase (B) Decrease (C) Remain unchanged (D) Data insufficient to predict relative pressure drop

Description : Two fluids are flowing through two similar pipes of the same diameter. The Reynold's number is same. For the same flow rate if the viscosity of a fluid is reduced to half the value of the ... (A) Increase (B) Decrease (C) Remain unchanged (D) Data insufficient to predict relative pressure drop

Last Answer : (B) Decrease

A fluid (µ/ρ) = 0.01 cm2 /sec is moving at critical flow condition (NRe = 2100) through a pipe of dia 3 cms. Velocity of flow is __________ cm/sec. (A) 7 (B) 700 (C) 7000 (D) 630

Description : A fluid (µ/ρ) = 0.01 cm2 /sec is moving at critical flow condition (NRe = 2100) through a pipe of dia 3 cms. Velocity of flow is __________ cm/sec. (A) 7 (B) 700 (C) 7000 (D) 630

Last Answer : (A) 7

Critical velocity in a pipe flow (A) Increases as fluid viscosity increases (B) Increases as pipe diameter increases (C) Independent of fluid density (D) None of these

Description : Critical velocity in a pipe flow (A) Increases as fluid viscosity increases (B) Increases as pipe diameter increases (C) Independent of fluid density (D) None of these

Last Answer : (B) Increases as pipe diameter increases

The Reynolds number of the liquid was increased 100 fold for a laminar falling film used for gas-liquid contacting. Assuming penetrating theory is applicable, the fold increase in the mass transfer co-efficient (Kc ) for the same system is(A) 100(B) 10(C) 5(D) 1.

Description : The Reynolds number of the liquid was increased 100 fold for a laminar falling film used for gas-liquid contacting. Assuming penetrating theory is applicable, the fold increase in the mass transfer co-efficient (Kc ) for the same system is. (A) 100 (B) 10 (C) 5 (D) 1

Last Answer : (B) 10

Stoke's equation is valid in the Reynolds number range (A) 0.01 to 0.1 (B) 0.1 to 2 (C) 2 to 10 (D) 10 to 100

Description : Stoke's equation is valid in the Reynolds number range (A) 0.01 to 0.1 (B) 0.1 to 2 (C) 2 to 10 (D) 10 to 100

Last Answer : (A) 0.01 to 0.1

To the present time, over _____ antibiotic substances have been described and approximately _____ such drugs are available to the medical practitioner. a. 10,000; 100 b. 8,000; 100 c. 6000; 300 d. 4,000; 400

Description : To the present time, over _____ antibiotic substances have been described and approximately _____ such drugs are available to the medical practitioner. a. 10,000; 100 b. 8,000; 100 c. 6000; 300 d. 4,000; 400

Last Answer : b. 8,000; 100

The following heat engine produces power of 100,000 kW. The heat engine operates between 800 K and 300 K. It has a thermal efficiency equal to 50% of that of the Carnot engine for the same temperature. The rate at which heat is absorbed from the hot reservoir is (A) 100,000 kW (B) 160,000 kW (C) 200,000 kW (D) 320,000 kW

Description : The following heat engine produces power of 100,000 kW. The heat engine operates between 800 K and 300 K. It has a thermal efficiency equal to 50% of that of the Carnot engine for the same temperature. The rate at which heat is ... is (A) 100,000 kW (B) 160,000 kW (C) 200,000 kW (D) 320,000 kW

Last Answer : (D) 320,000 kW

A resonant system has a fundamental frequency of 100 Hz. If the next higher frequency that gives a resonance are 300 Hz and 500 Hz, the system could be (a) A pip open at both ends (b) A pipe closed at both ends (c) A string vibrating between two fixed points (d) A pipe open at one end and closed at the other

Description : A resonant system has a fundamental frequency of 100 Hz. If the next higher frequency that gives a resonance are 300 Hz and 500 Hz, the system could be (a) A pip open at both ends (b) A pipe ... (c) A string vibrating between two fixed points (d) A pipe open at one end and closed at the other

Last Answer : Ans:(d)

Two taps P and Q can separately fill a tank in 120mins and 150 mins respectively. There is a 3rd tap in the bottom of the tank to empty it. If all of the 3 taps are simultaneously opened, then the tank is full in 100 mins. In how much time the 3rd pipe alone can empty the tank? A) 100 B) 200 C) 300 D) 400

Description : Two taps P and Q can separately fill a tank in 120mins and 150 mins respectively. There is a 3rd tap in the bottom of the tank to empty it. If all of the 3 taps are simultaneously opened, then the tank is full ... . In how much time the 3rd pipe alone can empty the tank? A) 100 B) 200 C) 300 D) 400

Last Answer : B Work done by the 3 tap in 1 min = 1/100 – ( 1/120 + 1/150) = 1/100 – (5+4/600) =1/100 – 9/600 =6-9/600 = - 3/600 = - 1/200(negative signs mean empting) Therefore the 3rd tap alone can empty the tank in 200 mins

Pick out the wrong statement. (A) The Reynolds analogy for mass transfer is given by Lewis relation and is applicable, when Schmidt number is one (B) Sherwood number for flow in pipes can be expressed as the ratio of the concentration gradient at wall to the overall concentration difference (C) According to film theory for equimolar counter diffusion, the mass transfer coefficient is given by DAB(B)P - 3, Q - 2 (D) The z-component of the total mass flux of a component A in binary mixture of A and B is given by - Dab'.dCA/dz

Description : Pick out the wrong statement. (A) The Reynolds analogy for mass transfer is given by Lewis relation and is applicable, when Schmidt number is one (B) Sherwood number for flow in pipes can be expressed ... flux of a component A in binary mixture of A and B is given by - Dab'.dCA/dz

Last Answer : (C) According to film theory for equimolar counter diffusion, the mass transfer coefficient is given by DAB(B)P - 3, Q - 2

Creeping flow around a sphere is defined, when particle Reynolds number is (A) < 2100 (B) < 0.1 (C) > 2.5 (D) < 500

Description : Creeping flow around a sphere is defined, when particle Reynolds number is (A) < 2100 (B) < 0.1 (C) > 2.5 (D) < 500

Last Answer : (B) < 0.1

Pick out the correct statement. (A) Fanning friction factor is inversely proportional to Reynolds number always (B) The property of a randomly packed bed (with raschig rings) is given by the ratio of the total volume to the volume of voids in the bed (C) Mach number in an incompressible fluid is always unity (D) Mach number is given by the ratio of the speed of the fluid to that of sound in the fluid under conditions of flow

Description : Pick out the correct statement. (A) Fanning friction factor is inversely proportional to Reynolds number always (B) The property of a randomly packed bed (with raschig rings) is given by the ratio of the ... the ratio of the speed of the fluid to that of sound in the fluid under conditions of flow

Last Answer : (D) Mach number is given by the ratio of the speed of the fluid to that of sound in the fluid under conditions of flow

The time taken for gravity flow of a fixed volume of liquid (as in Redwood viscometer) is directly proportional to its (A) Absolute viscosity (B) Ratio of absolute viscosity to density (C) Density (D) Reynolds number

Description : The time taken for gravity flow of a fixed volume of liquid (as in Redwood viscometer) is directly proportional to its (A) Absolute viscosity (B) Ratio of absolute viscosity to density (C) Density (D) Reynolds number

Last Answer : (B) Ratio of absolute viscosity to density

Boundary layer separation is characterised by one of the conditions given below, where 'Re' is the Reynolds number for the flow. Select the appropriate conditions. (A) Re << 1, accelerating flow (B) Re >> 1, accelerating flow (C) Re << 1, decelerating flow (D) Re >>1, decelerating flow

Description : Boundary layer separation is characterised by one of the conditions given below, where 'Re' is the Reynolds number for the flow. Select the appropriate conditions. (A) Re > 1, accelerating flow (C) Re >1, decelerating flow

Last Answer : (D) Re >>1, decelerating flow

Which of the following denotes the effect of compressibility in fluid flow? (A) Weber number (B) Mach number (C) Euler number (D) Reynolds number

Description : Which of the following denotes the effect of compressibility in fluid flow? (A) Weber number (B) Mach number (C) Euler number (D) Reynolds number

Last Answer : (B) Mach numbe

Laminar flow of a Newtonian fluid ceases to exist, when the Reynolds number exceeds (A) 4000 (B) 2100 (C) 1500 (D) 3000

Description : Laminar flow of a Newtonian fluid ceases to exist, when the Reynolds number exceeds (A) 4000 (B) 2100 (C) 1500 (D) 3000

Last Answer : (B) 2100

Isothermal turbulent flow of a fluid results in decrease of its pressure, which depends on the (A) Wall roughness (B) Reynolds number (C) Both (A) & (B) (D) Neither (A) nor (B)

Description : Isothermal turbulent flow of a fluid results in decrease of its pressure, which depends on the (A) Wall roughness (B) Reynolds number (C) Both (A) & (B) (D) Neither (A) nor (B)

Last Answer : (C) Both (A) & (B)

Which of the following equations applies to the fluid flow through a packed bed for very large Reynolds number? (A) Fanning equation (B) Blake-Plummer equation (C) Hagen-Poiseuille equation (D) Kozeny-Carman equation

Description : Which of the following equations applies to the fluid flow through a packed bed for very large Reynolds number? (A) Fanning equation (B) Blake-Plummer equation (C) Hagen-Poiseuille equation (D) Kozeny-Carman equation

Last Answer : (B) Blake-Plummer equation

The Reynolds number for an ideal fluid flow is (A) 4 (B) 2100-4000 (C) 4000 (D) ∞

Description : The Reynolds number for an ideal fluid flow is (A) 4 (B) 2100-4000 (C) 4000 (D) ∞

Last Answer : (D) ∞

For the Stoke's law to be valid in the case of a falling sphere in a fluid, the (A) Reynolds number (based on sphere diameter) should be < 1 (B) Flow around the sphere should be in turbulent region (C) Sphere must be metallic (D) Fluid density should be constant

Description : For the Stoke's law to be valid in the case of a falling sphere in a fluid, the (A) Reynolds number (based on sphere diameter) should be < 1 (B) Flow around the sphere should be in turbulent region (C) Sphere must be metallic (D) Fluid density should be constant

Last Answer : (C) Sphere must be metallic

Nusselt number is related to the Reynolds number (Re) in turbulent & laminar flow respectively as (A) Re0.5, Re0.8 (B) Re0.8, Re-0.5 (C) Re0.8, Re0.5 (D) Re-0.8, Re0.5

Description : Nusselt number is related to the Reynolds number (Re) in turbulent & laminar flow respectively as (A) Re0.5, Re0.8 (B) Re0.8, Re-0.5 (C) Re0.8, Re0.5 (D) Re-0.8, Re0.5

Last Answer : (C) Re0.8, Re0.5

Pick out the correct statement about the condensation. (A) Filmwise condensation gives a lower heat transfer rate than the dropwise condensation (B) Suitable coating or vapour additive is used to promote film wise condensation (C) If a condensing liquid does not wet the surface dropwise, even then condensation will take place on it (D) Reynolds number of condensing liquid is based on its mass flow rate

Description : Pick out the correct statement about the condensation. (A) Filmwise condensation gives a lower heat transfer rate than the dropwise condensation (B) Suitable coating or vapour additive is used to promote film ... place on it (D) Reynolds number of condensing liquid is based on its mass flow rate

Last Answer : (B) Suitable coating or vapour additive is used to promote film wise condensation

Experimental study of laminar fluid flow through a circular tube was conducted by(A) Reynolds(B) Hagen and Poiseuille(C) Pascal(D) Blake-Plummer

Description : Experimental study of laminar fluid flow through a circular tube was conducted by (A) Reynolds (B) Hagen and Poiseuille (C) Pascal (D) Blake-Plummer

Last Answer : (B) Hagen and Poiseuille

Which of the fluid forces are not considered in the Reynold's equation of flow? (A) Viscous forces (B) Turbulent forces (C) Pressure forces (D) Compressibility forces

Description : Which of the fluid forces are not considered in the Reynold's equation of flow? (A) Viscous forces (B) Turbulent forces (C) Pressure forces (D) Compressibility forces

Last Answer : (D) Compressibility forces

Energy reserves of an average well-fed adult man are about (A) 50,000 kcal (B) 100,000 kcal (C) 200,000 kcal (D) 300,000 kcal

Description : Energy reserves of an average well-fed adult man are about (A) 50,000 kcal (B) 100,000 kcal (C) 200,000 kcal (D) 300,000 kcal

Last Answer : Answer : B