The Nusselt number for fully developed (both thermally and
hydrodynamically) laminar flow through a circular pipe whose surface
temperature remains constant is
(A) 1.66
(B) 88.66
(C) 3.66
(D) Dependent on NRe only
Description : The Nusselt number for fully developed (both thermally and hydrodynamically) laminar flow through a circular pipe, where the wall heat flux is constant, is (A) 2.36 (B) 4.36 (C) 120.36 (D) Dependent on NRe only
Last Answer : (B) 4.36
Description : In case of laminar flow of fluid through a circular pipe, the (A) Shear stress over the cross-section is proportional to the distance from the surface of the pipe (B) Surface of velocity distribution is a ... occurs at a radial distance of 0.5 r from the centre of the pipe (r = pipe radius)
Last Answer : (B) Surface of velocity distribution is a paraboloid of revolution, whose volume equals half the volume of circumscribing cylinder
Description : Nusselt number for full developed, laminar, constant property flow in a pipe at uniform heat flux is (A) 0.72 (B) 4.364 (C) 18 (D) 83
Last Answer : (B) 4.364
Description : The ratio of average fluid velocity to the maximum velocity in case of laminar flow of a Newtonian fluid in a circular pipe is (A) 0.5 (B) 1 (C) 2 (D) 0.66
Last Answer : (A) 0.5
Description : Pick out the correct statement pertaining to transition/ entrance length in fluid flow. (A) The length of entrance region of pipe, in which full development of fluid flow takes place such that velocity profile does not change ... pipe of diameter 'd' is equal to 50 D (D) All (A), (B) and (C)
Last Answer : (D) All (A), (B) and (C)
Description : Efficiency of power transmission (η) through a circular pipe is given by (ht - hf )/ht , which has a maximum value of __________ percent. (A) 33:3 (B) 50 (C) 66.6 (D) 88.8
Last Answer : (C) 66.6
Description : Pick out the wrong statement. (A) The form drag is dependent upon the occurrence of a wake (B) The shear stress at any given cross-section of a pipe for steady flow (either laminar or turbulent ... of viscosity (D) Existence of the boundary layer in fluid flow is because of viscosity of the fluid
Last Answer : (C) An ideal fluid is the one, which has negligible surface tension and obeys the Newton's law of viscosity
Description : f = 16/NRe , is valid for (A) Turbulent flow (B) Laminar flow through an open channel (C) Steady flow (D) None of these
Last Answer : (D) None of these
Description : Consider the following statements in respect of steady laminar flow through a circular pipe: 1. Shear stress is zero on the central axis of the pipe 2. Discharge varies directly with the viscosity of the fluid 3. Velocity is maximum at the ... 2 , 3 & 4 (b) 1 & 3 only (c) 2 & 4 only (d)3 & 4 only
Last Answer : (b) 1 & 3 only
Description : For laminar flow of Newtonian fluids through a circular pipe, for a given pressure drop and length & diameter of pipe, the velocity of fluid is proportional to (where, μ = fluid viscosity ) (A) μ (B) 1/μ (C) √μ (D) 1/√μ
Last Answer : (B) 1/μ
Description : What is the ratio of total kinetic energy of fluid passing per second to the value obtained on the basis of average velocity (for laminar flow through a circular pipe)? (A) 0.5 (B) 1 (C) 1.5 (D) 2
Last Answer : (D) 2
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)
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
Description : Nusselt number is related to Grashoff number (Gr) in turbulent & laminar flow respectively, in respect of free convection over a vertical flat plate as (A) Gr0.25, Gr (B) Gr0.25, Gr0.33 (C) Gr, Gr0.25 (D) Gr0.33, Gr0.25
Last Answer : Option A
Description : The maximum discharge through a circular channel takes place, when the depth of the fluid flow is __________ times the pipe diameter. (A) 0.25 (B) 0.5 (C) 0.66 (D) 0.95
Last Answer : (D) 0.95
Description : For laminar flow of Newtonian fluid in a circular pipe, the velocitydistribution is a function of the distance 'd' measured from the centre line of the pipe, and it follows a __________ relationship. (A) Logarithmic (B) Parabolic (C) Hyperbolic (D) Linear
Last Answer : (B) Parabolic
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
Description : In the complete turbulence zone (in rough pipes), the (A) Rough and smooth pipes have the same friction factor (B) Laminar film covers the roughness projections (C) Friction factor depends upon NRe only (D) Friction factor is independent of the relative roughness
Last Answer : (D) Friction factor is independent of the relative roughness
Description : For turbulent flow of Newtonian fluid in a circular cross-section pipe, the ratio of maximum to average fluid velocity is (A) 0.5 (B) 1 (C) 0.66 (D) < 0.5
Last Answer : (B) 1
Description : The fluid velocity varies as the cube of the cylindrical pipe diameter in case of steady state laminar flow at constant pressure drop for __________ fluid. (A) Newtonian (B) Pseudo-plastic (C) Dilatent (D) Bingham plastic
Last Answer : (B) Pseudo-plastic
Description : The fluid velocity varies as the square of the cylindrical pipe diameter, in case of steady state laminar flow at constant pressure drop, for __________ fluid. (A) Newtonian (B) Dilatant (C) Pseudo-plastic (D) Non-Newtonian
Last Answer : (A) Newtonian
Description : The Prandtl mixing length is (A) Zero at the pipe wall and is a universal constant (B) Independent of radial distance from the pipe axis (C) Independent of the shear stress (D) Useful for computing laminar flow problems
Last Answer : (D) Useful for computing laminar flow problems
Description : The fluid velocity varies as the square root of the cylindrical pipe diameter in case of steady state laminar flow at constant pressure drop of __________ fluid. (A) Dilatent (B) Pseudo-plastic (C) Bingham plastic (D) Newtonian
Last Answer : (A) Dilatent
Description : Prandtl mixing length is (A) Applicable to laminar flow problems (B) A universal constant (C) Zero at the pipe wall (D) None of these
Last Answer : (C) Zero at the pipe wall
Description : For a laminar flow of fluid in a circular tube, 'h1 ' is the convective heat transfer co-efficient at velocity 'V1 '. If the velocity is reduced by half and assuming the fluid properties are constant, the new convective heat transfer co-efficient is (A) 1.26 h1 (B) 0.794 h1 (C) 0.574 h1 (D) 1.741 h1
Last Answer : (B) 0.794 h1
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
Description : The distribution of shear stress in a stream of fluid in a circular tube is (A) Linear with radius for turbulent flow only (B) Linear with radius for laminar flow only (C) Linear with radius for both laminar & turbulent flow (D) Parabolic with radius for both laminar & turbulent flow
Last Answer : (C) Linear with radius for both laminar & turbulent flow
Description : Intensive property of a system is one whose value (a) depends on the mass of the system, like volume (b) does not depend on the mass of the system, like temperature, pressure, etc. (c) is not ... on the state (d) is dependent on the path followed and not on the state (e) remains constant.
Last Answer : Answer : b
Description : The characteristic dimensionless groups for heat transfer to a fluid flowing through a pipe in laminar flow are (A) Re.Gz (B) Nu, Pr (C) Nu, Pr, Re (D) Nu, Gz
Last Answer : (D) Nu, Gz
Description : Discharge in laminar flow through a pipe varies (A) As the square of the radius (B) Inversely as the pressure drop (C) Inversely as the viscosity (D) As the square of the diameter
Last Answer : (A) As the square of the radius
Description : The pressure drop per unit length for laminar flow of fluid through a long pipe is proportional to (where, A = cross-sectional area of the pipe & D = Diameter of the pipe) (A) A (B) D (C) 1/A (D) 1/A2
Last Answer : (C) 1/A
Description : Transition from laminar flow to turbulent flow in fluid flow through a pipe does not depend upon the (A) Length of the pipe (B) Diameter of the pipe (C) Density of the fluid (D) Velocity of the fluid
Last Answer : (A) Length of the pipe
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
Description : Nusselt number is the ratio of the temperature gradient at the wall to (A) Temperature difference (B) Heat flux (C) That across the entire pipe (D) None of these
Last Answer : (C) That across the entire pipe
Description : The non-dimensional temperature gradient in a liquid at the wall of a pipe is the (A) Heat flux (B) Nusselt number (C) Prandtl number (D) Schmidt number
Last Answer : (A) Heat flux
Description : Nusselt number is the ratio of the (A) Temperature gradient of the wall to that across the entire pipe (B) Temperature difference to the temperature gradient at the wall (C) Heat flux at the wall to that across the entire pipe (D) None of these
Last Answer : (C) Heat flux at the wall to that across the entire pipe
Description : The kinetic energy correction factor for velocity distribution of laminar flow is (A) 0.5 (B) 1.66 (C) 1 (D) 2
Last Answer : (B) 1.66
Description : The momentum correction factor for the velocity distribution of laminar flow is (A) 1.3 (B) 1.66 (C) 2.5 (D) None of these
Description : In a fully turbulent flow (Re > 10 5 ) in a pipe of diameter 'd', for a constant pressure gradient, the dependence of volumetric flow rate of an incompressible fluid is (A) d (B) d 2 (C) d 2.5 (D) d
Last Answer : (C) d 2.5
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
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
Description : Pick out the wrong statement. (A) The shear stress at the pipe (dia = D, length = L) wall in case of laminar flow of Newtonian fluids is (D/4L). ∆p (B) In the equation, T. gc = k. ... to motion (D) With increase in the Mach number >0.6, the drag co-efficient decreases in case of compressible fluids
Last Answer : (D) With increase in the Mach number >0.6, the drag co-efficient decreases in case of compressible fluids
Description : Pick out the wrong statement pertaining to the analogy between equations of heat and mass transfer operations. (A) Sherwood number in mass transfer is analogous to Nusselt number in heat transfer ... heat transfer (D) Reynolds number remains the same in both heat and mass transfer
Last Answer : (C) Reynolds number in mass transfer is analogous to Grashoff number in heat transfer
Description : Assuming flow to be laminar, if the diameter of the pipe is halved, then the pressure drop will (A) Increase (B) Decrease (C) Remain same (D) Be quadrupled
Last Answer : (A) Increase
Description : 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) > 2 (D) 1/2
Last Answer : (A) 2
Description : Heat transfer co-efficient (h) for a fluid flowing inside a clean pipe is given by h = 0.023 (K/D) (DVρ/µ) 0.8 (CP .µ/k) 0.4 . This is valid for the value of NRe equal to (A) < 2100 (B) 2100-4000 (C) > 4000 (D) > 10000
Last Answer : (D) > 10000
Description : Friction factor for a hydraulically smooth pipe at NRe = 2100 is f1 . If the pipe is further smoothened (i.e., roughness is reduced), the friction factor at the same value of NRe , will (A) Increase (B) Decrease (C) Remain unchanged (D) Increase or decrease depending on the pipe material
Description : What is the value of Fanning friction factor f ' for smooth pipe at NRe = 10 6 approximately? (A) 0.003 (B) 0.01 (C) 0.1 (D) 0.3
Last Answer : (A) 0.003
Description : The moment of inertia of a hollow circular section whose external diameter is 8 cm and interial diameter is 6 cm about the axis passing through its centre is a.66.8 cm4 b.137.5 cm4 c.550 cm4 d.33.4 cm4 e.275 cm4
Last Answer : b. 137.5 cm4
Description : 05. The flow in a pipe is laminar, when Reynold number is less than 2000. A) True B) False
Last Answer : A