Turbulent Flow in Engineering Mechanics: Master Your Fluid Dynamics Knowledge

Question 1

In fluid dynamics, which parameter is the primary determinant in distinguishing between laminar and turbulent flow?

Accepted Answer

Reynolds number

Answer

Flow velocity

Answer

Fluid viscosity

Question 2

The Reynolds number is primarily used to determine:

Accepted Answer

The balance between inertial and viscous forces in fluid flow

Answer

The pressure drop in a pipe

Answer

The velocity of a fluid

Answer

The density of a fluid

Question 3

Which factor generally leads to an increase in drag force in turbulent flow?

Accepted Answer

Increased fluid density

Answer

Decreased flow velocity

Answer

Smoother pipe surfaces

Answer

Lower Reynolds number

Question 4

What is the main difference between laminar and turbulent flow?

Accepted Answer

Turbulent flow occurs at high Reynolds numbers, while laminar flow occurs at low Reynolds numbers

Answer

Laminar flow has low friction, while turbulent flow has high friction

Answer

Laminar flow exhibits chaotic patterns, while turbulent flow is smooth

Answer

Laminar flow is characterized by eddies, while turbulent flow is not

Question 5

Which of the following is a characteristic of turbulent flow?

Accepted Answer

Random velocity fluctuations and chaotic behavior

Answer

High viscosity and laminar layers

Answer

Steady and smooth flow

Answer

Uniform velocity distribution across the flow section

Question 6

The Reynolds number is a dimensionless quantity used to primarily characterize:

Accepted Answer

Flow regime and transition between laminar and turbulent flow

Answer

Drag force acting on a body

Answer

Boundary layer thickness

Answer

Heat transfer rate

Question 7

In turbulent flow, the friction factor is typically:

Accepted Answer

Proportional to Reynolds number

Answer

Constant and independent of Reynolds number

Answer

Proportional to Reynolds number squared

Answer

Inversely proportional to Reynolds number

Question 8

How does turbulence affect boundary layer characteristics?

Accepted Answer

Increases thickness, distorts velocity profile, increases shear stress

Answer

Increases thickness, flattens velocity profile, decreases shear stress

Answer

Decreases thickness, distorts velocity profile, increases shear stress

Answer

Decreases thickness, flattens velocity profile, decreases shear stress

Question 9

In turbulent flow characterization, which dimensionless number signifies the transition from laminar to turbulent flow?

Accepted Answer

Reynolds number

Answer

Froude number

Answer

Mach number

Answer

Grashof number

Question 10

In turbulent flow analysis, the Reynolds stress tensor represents:

Accepted Answer

Shear stress due to turbulent velocity fluctuations

Answer

Shear stress due to mean velocity gradients

Answer

Normal stress due to mean pressure gradients

Answer

Total stress acting on the fluid

Question 11

In a turbulent pipe flow, the region near the pipe wall influenced by viscous effects is known as the:

Accepted Answer

Viscous sublayer

Answer

Buffer layer

Answer

Transition layer

Answer

Turbulent core

Question 12

Which of the following is NOT a distinguishing characteristic of turbulent flow?

Accepted Answer

Laminar layers

Answer

High Reynolds number

Answer

Unpredictable and chaotic flow patterns

Answer

Increased drag

Question 13

The Reynolds number is a dimensionless parameter that represents the ratio of:

Accepted Answer

Inertia forces to viscous forces

Answer

Pressure forces to viscous forces

Answer

Gravitational forces to inertia forces

Answer

Elastic forces to viscous forces

Question 14

The significant increase in drag in turbulent flow compared to laminar flow is primarily attributed to:

Accepted Answer

Formation of eddies and vortices

Answer

Increased friction between fluid layers

Answer

Higher kinetic energy of the fluid

Answer

Reduced pressure gradient

Question 15

Which flow regime is characterized by the highest shear stress?

Accepted Answer

Turbulent flow

Answer

Laminar flow

Answer

Poiseuille flow

Answer

Couette flow

Question 16

Turbulent flow is commonly modelled using which set of governing equations?

Accepted Answer

Navier-Stokes equations

Answer

Bernoulli equation

Answer

Euler equations

Answer

Continuity equation

Question 17

Which dimensionless parameter indicates the transition between laminar and turbulent flow?

Accepted Answer

Reynolds number

Answer

Froude number

Answer

Weber number

Answer

Mach number

Question 18

The turbulent kinetic energy (TKE) primarily represents:

Accepted Answer

The average kinetic energy of the turbulent eddies

Answer

The energy dissipated due to friction

Answer

The potential energy of the fluid

Answer

The heat transfer rate

Question 19

The energy cascade in turbulent flow describes:

Accepted Answer

The transfer of energy from large eddies to smaller ones

Answer

The dissipation of energy into heat

Answer

The increase in energy with flow distance

Answer

The formation of vortices

Question 20

Prandtl's mixing length theory is based on the assumption that:

Accepted Answer

The turbulent eddies have a characteristic length scale

Answer

The turbulent eddies are isotropic

Answer

The turbulent viscosity is proportional to the shear stress

Answer

The mean velocity profile is parabolic

Question 21

A limitation of using Reynolds-averaged Navier-Stokes (RANS) equations is that:

Accepted Answer

They cannot capture unsteady and large-scale turbulent structures

Answer

They require a significant amount of computational resources

Answer

They are unsuitable for flows with complex geometries

Answer

They are not accurate for low Reynolds numbers