Fluid Mechanics interview questions

1. A.sum of pressure head, velocity head and elevation head stays constant along a streamline for steady, incompressible, inviscid flow
2. B.pressure applied to a confined fluid at rest is transmitted undiminished in every direction, the principle behind hydraulic jacks and presses
3. C.distance between the centre of gravity and the metacentre of a floating body, which must be positive for stable equilibrium
4. D.detachment of flow from a surface under an adverse pressure gradient, creating a wake and a large pressure drag

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1. A.Pascal's law
2. B.Bernoulli's equation
3. C.Cavitation in pumps
4. D.Displacement thickness

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1. A.Pascal's law — detachment of flow from a surface under an adverse pressure gradient, creating a wake and a large pressure drag
2. B.Pascal's law — head loss in a pipe hf = fLV²/2gD, with the friction factor read from the Moody chart for turbulent flow
3. C.Pascal's law — ratio of inertia to viscous forces ρVD/μ, with pipe flow laminar below about 2000 and fully turbulent above 4000
4. D.Pascal's law — pressure applied to a confined fluid at rest is transmitted undiminished in every direction, the principle behind hydraulic jacks and presses

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1. A.the statement that mass flow rate is conserved along a streamtube, so density times area times velocity stays constant in steady flow
2. B.distance between the centre of gravity and the metacentre of a floating body, which must be positive for stable equilibrium
3. C.sum of pressure head, velocity head and elevation head stays constant along a streamline for steady, incompressible, inviscid flow
4. D.head loss in a pipe hf = fLV²/2gD, with the friction factor read from the Moody chart for turbulent flow

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1. A.Bernoulli's equation
2. B.Cavitation in pumps
3. C.Displacement thickness
4. D.Froude number

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1. A.Bernoulli's equation — vapour bubbles form where local pressure falls below vapour pressure and collapse on the impeller, avoided by keeping NPSH available above NPSH required
2. B.Bernoulli's equation — the statement that mass flow rate is conserved along a streamtube, so density times area times velocity stays constant in steady flow
3. C.Bernoulli's equation — pressure applied to a confined fluid at rest is transmitted undiminished in every direction, the principle behind hydraulic jacks and presses
4. D.Bernoulli's equation — sum of pressure head, velocity head and elevation head stays constant along a streamline for steady, incompressible, inviscid flow

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1. A.sum of pressure head, velocity head and elevation head stays constant along a streamline for steady, incompressible, inviscid flow
2. B.the statement that mass flow rate is conserved along a streamtube, so density times area times velocity stays constant in steady flow
3. C.index N√Q/H^0.75 that classifies impeller shape from radial (low values) to axial (high values) for a given duty
4. D.ratio of inertia to viscous forces ρVD/μ, with pipe flow laminar below about 2000 and fully turbulent above 4000

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1. A.Pascal's law
2. B.Boundary layer separation
3. C.Metacentric height
4. D.Reynolds number

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1. A.Reynolds number — vapour bubbles form where local pressure falls below vapour pressure and collapse on the impeller, avoided by keeping NPSH available above NPSH required
2. B.Reynolds number — sum of pressure head, velocity head and elevation head stays constant along a streamline for steady, incompressible, inviscid flow
3. C.Reynolds number — the distance by which a boundary would have to be shifted outward for an ideal fluid to carry the same mass flow deficit as the real boundary layer
4. D.Reynolds number — ratio of inertia to viscous forces ρVD/μ, with pipe flow laminar below about 2000 and fully turbulent above 4000

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1. A.ratio of inertia to viscous forces ρVD/μ, with pipe flow laminar below about 2000 and fully turbulent above 4000
2. B.a scalar whose constant-value lines are streamlines and whose difference between two streamlines equals the volume flow rate between them
3. C.the statement that mass flow rate is conserved along a streamtube, so density times area times velocity stays constant in steady flow
4. D.distance between the centre of gravity and the metacentre of a floating body, which must be positive for stable equilibrium

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1. A.Metacentric height
2. B.Darcy-Weisbach equation
3. C.Hagen-Poiseuille flow
4. D.Specific speed of a pump

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1. A.Metacentric height — head loss in a pipe hf = fLV²/2gD, with the friction factor read from the Moody chart for turbulent flow
2. B.Metacentric height — the distance by which a boundary would have to be shifted outward for an ideal fluid to carry the same mass flow deficit as the real boundary layer
3. C.Metacentric height — distance between the centre of gravity and the metacentre of a floating body, which must be positive for stable equilibrium
4. D.Metacentric height — the ratio of inertia to gravity forces, which classifies open-channel flow as subcritical, critical or supercritical

Answer + AI explanation with Pro

1. A.ratio of inertia to viscous forces ρVD/μ, with pipe flow laminar below about 2000 and fully turbulent above 4000
2. B.head loss in a pipe hf = fLV²/2gD, with the friction factor read from the Moody chart for turbulent flow
3. C.detachment of flow from a surface under an adverse pressure gradient, creating a wake and a large pressure drag
4. D.a scalar whose constant-value lines are streamlines and whose difference between two streamlines equals the volume flow rate between them

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1. A.Darcy-Weisbach equation
2. B.Metacentric height
3. C.Pascal's law
4. D.Stream function

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1. A.Darcy-Weisbach equation — distance between the centre of gravity and the metacentre of a floating body, which must be positive for stable equilibrium
2. B.Darcy-Weisbach equation — ratio of inertia to viscous forces ρVD/μ, with pipe flow laminar below about 2000 and fully turbulent above 4000
3. C.Darcy-Weisbach equation — the ratio of inertia to gravity forces, which classifies open-channel flow as subcritical, critical or supercritical
4. D.Darcy-Weisbach equation — head loss in a pipe hf = fLV²/2gD, with the friction factor read from the Moody chart for turbulent flow

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1. A.head loss in a pipe hf = fLV²/2gD, with the friction factor read from the Moody chart for turbulent flow
2. B.laminar pipe flow in which friction factor is 64/Re and pressure drop is proportional to viscosity, length and flow rate
3. C.detachment of flow from a surface under an adverse pressure gradient, creating a wake and a large pressure drag
4. D.distance between the centre of gravity and the metacentre of a floating body, which must be positive for stable equilibrium

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1. A.Hagen-Poiseuille flow
2. B.Reynolds number
3. C.Displacement thickness
4. D.Metacentric height

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1. A.Hagen-Poiseuille flow — detachment of flow from a surface under an adverse pressure gradient, creating a wake and a large pressure drag
2. B.Hagen-Poiseuille flow — the distance by which a boundary would have to be shifted outward for an ideal fluid to carry the same mass flow deficit as the real boundary layer
3. C.Hagen-Poiseuille flow — laminar pipe flow in which friction factor is 64/Re and pressure drop is proportional to viscosity, length and flow rate
4. D.Hagen-Poiseuille flow — sum of pressure head, velocity head and elevation head stays constant along a streamline for steady, incompressible, inviscid flow

Answer + AI explanation with Pro

1. A.the distance by which a boundary would have to be shifted outward for an ideal fluid to carry the same mass flow deficit as the real boundary layer
2. B.head loss in a pipe hf = fLV²/2gD, with the friction factor read from the Moody chart for turbulent flow
3. C.a scalar whose constant-value lines are streamlines and whose difference between two streamlines equals the volume flow rate between them
4. D.detachment of flow from a surface under an adverse pressure gradient, creating a wake and a large pressure drag

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1. A.Boundary layer separation
2. B.Darcy-Weisbach equation
3. C.Stream function
4. D.Hagen-Poiseuille flow

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1. A.Boundary layer separation — sum of pressure head, velocity head and elevation head stays constant along a streamline for steady, incompressible, inviscid flow
2. B.Boundary layer separation — vapour bubbles form where local pressure falls below vapour pressure and collapse on the impeller, avoided by keeping NPSH available above NPSH required
3. C.Boundary layer separation — index N√Q/H^0.75 that classifies impeller shape from radial (low values) to axial (high values) for a given duty
4. D.Boundary layer separation — detachment of flow from a surface under an adverse pressure gradient, creating a wake and a large pressure drag

Answer + AI explanation with Pro

1. A.ratio of inertia to viscous forces ρVD/μ, with pipe flow laminar below about 2000 and fully turbulent above 4000
2. B.distance between the centre of gravity and the metacentre of a floating body, which must be positive for stable equilibrium
3. C.pressure applied to a confined fluid at rest is transmitted undiminished in every direction, the principle behind hydraulic jacks and presses
4. D.vapour bubbles form where local pressure falls below vapour pressure and collapse on the impeller, avoided by keeping NPSH available above NPSH required

Answer + AI explanation with Pro

1. A.Cavitation in pumps
2. B.Displacement thickness
3. C.Darcy-Weisbach equation
4. D.Boundary layer separation

Answer + AI explanation with Pro

1. A.Cavitation in pumps — distance between the centre of gravity and the metacentre of a floating body, which must be positive for stable equilibrium
2. B.Cavitation in pumps — a scalar whose constant-value lines are streamlines and whose difference between two streamlines equals the volume flow rate between them
3. C.Cavitation in pumps — vapour bubbles form where local pressure falls below vapour pressure and collapse on the impeller, avoided by keeping NPSH available above NPSH required
4. D.Cavitation in pumps — head loss in a pipe hf = fLV²/2gD, with the friction factor read from the Moody chart for turbulent flow

Answer + AI explanation with Pro

1. A.vapour bubbles form where local pressure falls below vapour pressure and collapse on the impeller, avoided by keeping NPSH available above NPSH required
2. B.index N√Q/H^0.75 that classifies impeller shape from radial (low values) to axial (high values) for a given duty
3. C.a scalar whose constant-value lines are streamlines and whose difference between two streamlines equals the volume flow rate between them
4. D.laminar pipe flow in which friction factor is 64/Re and pressure drop is proportional to viscosity, length and flow rate

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1. A.Darcy-Weisbach equation
2. B.Boundary layer separation
3. C.Specific speed of a pump
4. D.Continuity equation

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1. A.Specific speed of a pump — pressure applied to a confined fluid at rest is transmitted undiminished in every direction, the principle behind hydraulic jacks and presses
2. B.Specific speed of a pump — laminar pipe flow in which friction factor is 64/Re and pressure drop is proportional to viscosity, length and flow rate
3. C.Specific speed of a pump — a scalar whose constant-value lines are streamlines and whose difference between two streamlines equals the volume flow rate between them
4. D.Specific speed of a pump — index N√Q/H^0.75 that classifies impeller shape from radial (low values) to axial (high values) for a given duty

Answer + AI explanation with Pro

1. A.sum of pressure head, velocity head and elevation head stays constant along a streamline for steady, incompressible, inviscid flow
2. B.the ratio of inertia to gravity forces, which classifies open-channel flow as subcritical, critical or supercritical
3. C.the statement that mass flow rate is conserved along a streamtube, so density times area times velocity stays constant in steady flow
4. D.pressure applied to a confined fluid at rest is transmitted undiminished in every direction, the principle behind hydraulic jacks and presses

Answer + AI explanation with Pro

1. A.Froude number
2. B.Continuity equation
3. C.Boundary layer separation
4. D.Cavitation in pumps

Answer + AI explanation with Pro

1. A.Continuity equation — distance between the centre of gravity and the metacentre of a floating body, which must be positive for stable equilibrium
2. B.Continuity equation — the ratio of inertia to gravity forces, which classifies open-channel flow as subcritical, critical or supercritical
3. C.Continuity equation — the statement that mass flow rate is conserved along a streamtube, so density times area times velocity stays constant in steady flow
4. D.Continuity equation — index N√Q/H^0.75 that classifies impeller shape from radial (low values) to axial (high values) for a given duty

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