Viscous Flow: Master Fluid Dynamics with Friction

Question 1

The dimensionless parameter that distinguishes between laminar and turbulent flow is:

Accepted Answer

Reynolds number

Answer

Nusselt number

Answer

Grashof number

Answer

Prandtl number

Question 2

The boundary layer concept in viscous flow refers to:

Accepted Answer

A region near solid surfaces with significant velocity gradients

Answer

A layer of zero velocity directly at solid surfaces

Answer

A region of constant pressure gradient

Answer

A layer of high turbulence intensity

Question 3

The pressure drop in a turbulent pipe flow is primarily proportional to:

Accepted Answer

Flow velocity squared

Answer

Flow length

Answer

Pipe diameter

Answer

Fluid viscosity

Question 4

Define laminar flow, highlighting its distinguishing characteristic.

Accepted Answer

Flow characterized by smooth, orderly layers of fluid

Answer

Flow with irregular, chaotic fluid movement

Answer

Flow where the fluid velocity increases linearly with distance from the boundary

Answer

Flow where the pressure drop is proportional to the velocity squared

Question 5

The Reynolds number is a dimensionless parameter used to assess the relative significance of inertial and viscous forces in fluid flow. Express the formula for the Reynolds number.

Accepted Answer

Inertial forces / Viscous forces

Answer

Viscous forces / Inertial forces

Answer

Pressure forces / Viscous forces

Answer

Gravitational forces / Viscous forces

Question 6

Boundary layer theory is based on simplifying assumptions. Identify the assumption that is NOT part of boundary layer theory.

Accepted Answer

Fluid velocity at the boundary is non-zero

Answer

Flow is steady and incompressible

Answer

Viscous effects are predominant in a thin region near the boundary

Answer

Pressure gradient is negligible throughout the boundary layer

Question 7

Centrifugal pumps are commonly used in fluid systems. Describe the primary function of a centrifugal pump.

Accepted Answer

Increases fluid pressure through centrifugal force

Answer

Converts fluid kinetic energy into potential energy

Answer

Decreases fluid velocity by increasing the flow area

Answer

Generates a vacuum to remove fluid

Question 8

The boundary layer is a region of fluid near a solid surface where:

Accepted Answer

Velocity gradients are significant

Answer

Velocity is zero

Answer

Velocity is constant

Answer

Turbulence is predominant

Question 9

In a pipe with a large diameter and low velocity, the flow is likely to be:

Accepted Answer

Laminar

Answer

Turbulent

Answer

Viscous

Answer

Inviscid

Question 10

Which type of pump employs the boundary layer effect to move fluids?

Accepted Answer

Centrifugal pump

Answer

Axial flow pump

Answer

Positive displacement pump

Answer

Magnetic-drive pump

Question 11

The velocity profile in a turbulent boundary layer can be best approximated by:

Accepted Answer

Logarithmic relationship

Answer

Linear relationship

Answer

Parabolic relationship

Answer

Exponential relationship

Question 12

To reduce friction drag in pipe flows, one can:

Accepted Answer

Polish the pipe surface

Answer

Increase the fluid temperature

Answer

Add roughness elements to the pipe wall

Answer

Increase fluid viscosity

Question 13

In fluid dynamics, which dimensionless number is used to determine the transition from laminar to turbulent flow?

Accepted Answer

Reynolds Number

Answer

Mach Number

Answer

Froude Number

Answer

Weber Number

Question 14

In laminar flow, the velocity profile is:

Accepted Answer

Parabolic

Answer

Linear

Answer

Exponential

Answer

Hyperbolic

Question 15

The ratio of inertial forces to viscous forces is quantified by which dimensionless number?

Accepted Answer

Reynolds number

Answer

Froude number

Answer

Weber number

Answer

Euler number

Question 16

Which dimensionless number characterizes fluid flow in a porous medium?

Accepted Answer

Darcy number

Answer

Reynolds number

Answer

Prandtl number

Answer

Stanton number

Question 17

In microfluidics, the dominant force responsible for fluid flow is:

Accepted Answer

Viscous forces

Answer

Gravity

Answer

Inertial forces

Answer

Pressure forces

Question 18

Fluid flows characterized by high Reynolds numbers and chaotic flow patterns are:

Accepted Answer

Turbulent flows

Answer

Laminar flows

Answer

Couette flows

Answer

Poiseuille flows

Question 19

The critical Reynolds number is significant because it:

Accepted Answer

Indicates the transition from laminar to turbulent flow.

Answer

Represents the maximum Reynolds number for which laminar flow is stable.

Answer

Determines the fluid velocity at which turbulence occurs.

Answer

Is independent of fluid properties and flow conditions.

Question 20

A common type of drag force in viscous flow is:

Accepted Answer

Skin friction drag

Answer

Pressure drag

Answer

Form drag

Answer

Wave drag

Question 21

Steady viscous flow is distinguished from unsteady viscous flow by having:

Accepted Answer

Constant fluid properties

Answer

Time-varying fluid properties

Answer

Closed system boundaries

Answer

Open system boundaries

Question 22

In a circular pipe, the velocity profile for fully developed turbulent flow is:

Accepted Answer

Logarithmic

Answer

Parabolic

Answer

Linear

Answer

Exponential

Question 23

The Navier-Stokes equations are a set of:

Accepted Answer

Partial differential equations

Answer

Algebraic equations

Answer

Ordinary differential equations

Answer

Integral equations

Question 24

The boundary condition for fluid flowing over a stationary solid surface is:

Accepted Answer

Zero velocity

Answer

Zero shear stress

Answer

Zero pressure gradient

Answer

Zero temperature gradient

Question 25

Which of the following is a defining characteristic of laminar flow?

Accepted Answer

Smooth, orderly fluid motion

Answer

High fluid velocity

Answer

Presence of eddies and turbulence

Answer

Rapid mixing of fluids

Question 26

The flow regime of a fluid can be characterized by which dimensionless parameter?

Accepted Answer

Reynolds number

Answer

Froude number

Answer

Mach number

Answer

Peclet number

Question 27

In fluid dynamics, what does the boundary layer theory analyze?

Accepted Answer

Flow near solid surfaces

Answer

Flow around obstacles

Answer

Compressible fluid flow

Answer

Multiphase flow

Question 28

Which of these is NOT considered a type of fluid machinery?

Accepted Answer

Internal combustion engines

Answer

Centrifugal pumps

Answer

Axial flow turbines

Answer

Heat exchangers

Question 29

The viscosity of a fluid relates to its:

Accepted Answer

Resistance to flow

Answer

Density

Answer

Compressibility

Answer

Surface tension

Question 30

Which dimensionless parameter represents the ratio of inertial forces to viscous forces in fluid flow?

Accepted Answer

Reynolds number

Answer

Froude number

Answer

Mach number

Answer

Euler number

Question 31

The pressure drop in a pipe is primarily caused by:

Accepted Answer

Friction

Answer

Gravity

Answer

Expansion

Answer

Acceleration

Question 32

Laminar flow is characterized by:

Accepted Answer

Low fluid velocity and high viscosity

Answer

High fluid velocity and low viscosity

Answer

High fluid velocity and high viscosity

Answer

Low fluid velocity and low viscosity

Question 33

The boundary layer is the region of the fluid:

Accepted Answer

Immediately adjacent to the solid surface

Answer

At the center of the pipe

Answer

Where the velocity is zero

Answer

Where the pressure is highest

Question 34

Turbulent flow is characterized by:

Accepted Answer

Irregular and chaotic fluid motion

Answer

Smooth and orderly fluid motion

Answer

High pressure and low velocity

Answer

Low pressure and high velocity

Question 35

The Reynolds number is a dimensionless parameter used to determine:

Accepted Answer

Flow regime (laminar or turbulent)

Answer

Fluid velocity

Answer

Fluid viscosity

Answer

Pipe diameter

Question 36

The transition from laminar to turbulent flow in a pipe depends on:

Accepted Answer

A combination of fluid velocity, viscosity, and pipe diameter

Answer

Fluid velocity only

Answer

Viscosity only

Answer

Pipe diameter only

Question 37

The Navier-Stokes equations are a set of partial differential equations that describe:

Accepted Answer

Flow of a viscous fluid

Answer

Laminar flow in a pipe

Answer

Turbulent flow in a boundary layer

Answer

Flow of an inviscid fluid

Question 38

In viscous flow, the shear stress within a fluid is proportional to the:

Accepted Answer

Velocity gradient

Answer

Fluid density

Answer

Pressure gradient

Answer

Gravitational acceleration

Question 39

Which of the following accurately describes the characteristic motion of laminar flow?

Accepted Answer

Smooth, orderly fluid motion with distinct layers

Answer

Irregular, unpredictable fluid motion with significant turbulence

Answer

High pressure drop and energy loss

Answer

Formation of eddies and vortices

Question 40

The primary application of boundary layer theory is in analyzing fluid flow behavior near which type of surfaces?

Accepted Answer

Solid surfaces

Answer

Free surfaces

Answer

Curved surfaces

Answer

Heated surfaces

Question 41

Which of the following factors is not considered in the calculation of the Reynolds number?

Accepted Answer

Fluid temperature

Answer

Fluid velocity

Answer

Pipe diameter

Answer

Fluid viscosity

Question 42

In a pipe, the transition from laminar to turbulent flow typically occurs when the Reynolds number surpasses:

Accepted Answer

2500

Answer

2000

Answer

3000

Answer

3500

Question 43

A significant application of viscous flow principles in fluid machinery is found in the:

Accepted Answer

Design of pumps and turbines

Answer

Analysis of flow in pipelines

Answer

Optimization of aircraft aerodynamics

Answer

Modeling of combustion processes

Question 44

Which of the following accurately characterizes turbulent flow?

Accepted Answer

High energy dissipation

Answer

Low pressure drop

Answer

Predictable flow patterns

Answer

Thin boundary layers

Question 45

Which of the following most clearly distinguishes laminar flow from turbulent flow?

Accepted Answer

Laminar flow has smooth, well-defined layers, while turbulent flow is characterized by random, chaotic motion.

Answer

Laminar flow is observed at higher Reynolds numbers than turbulent flow.

Answer

Turbulent flow leads to lower pressure drop compared to laminar flow.

Answer

Laminar flow is preferred for high-precision applications, while turbulent flow is favored for high-efficiency applications.

Question 46

What is the critical significance of the boundary layer in viscous flow?

Accepted Answer

The boundary layer is the region near a solid surface where fluid velocity is influenced by viscous forces.

Answer

The boundary layer thickness increases with increasing distance from the surface.

Answer

The boundary layer is only significant in low-speed flows.

Answer

The boundary layer can significantly contribute to pressure drag on objects in a flow.

Question 47

What is the primary function of the Darcy-Weisbach equation?

Accepted Answer

Calculating pressure drop in pipe flow

Answer

Determining the velocity profile in a boundary layer

Answer

Predicting the Reynolds number for a given flow

Answer

Estimating the onset of turbulence in a pipe flow

Question 48

In a centrifugal pump, what type of flow typically occurs within the rotating impeller?

Accepted Answer

Turbulent flow

Answer

Laminar flow

Answer

Viscous flow

Answer

Potential flow

Question 49

Which parameter is crucial in determining whether a flow can be classified as creeping flow?

Accepted Answer

Reynolds number

Answer

Froude number

Answer

Mach number

Answer

Weber number