The velocity at cross-stream of a turbulent wake is calculated using the formula\(\frac{U_{max}-U}{U_{max}-U_{min}}=b(\frac{y}{b})\) Note:Umax→ Maximum velocity at a particular cross-sectionUmin→ Minimum velocity at a particular cross-sectiony → Distance in the cross-stream direction from the centre line at the cross sectionb → Cross-stream half widthU → Velocity at the distance ‘y’The minimum velocity here corresponds to _____________

Velocities of the surrounding free stream

Velocities just downstream of the object

Velocities of the surrounding free stream

Which of these is correct for turbulent jets?Note:Umax → Maximum velocity at a particular cross-sectionUmin → Minimum velocity at a particular cross-sectiony → Distance in the cross-stream direction from the centre line at the cross sectionb → Cross-stream half widthU → Velocity at the distance ‘y’.

\(\frac{U}{U_{max}-U_{min}}=a(\frac{y}{b})\)

\(\frac{U_{max}-U}{U_{max}-U_{min}}=b(\frac{y}{b})\)

\(\frac{U-U_{min}}{U_{max}-U_{min}}=c(\frac{y}{b})\)

\(\frac{U}{U_{max}}=d(\frac{y}{b})\)

Which of these is correct for mixing layer turbulent flows?Note:Umax → Maximum velocity at a particular cross-sectionUmin → Minimum velocity at a particular cross-sectiony → Distance in the cross-stream direction from the centre line at the cross sectionb → Cross-stream half widthU → Velocity at the distance ‘y’.

\(\frac{U}{U_{max}-U_{min}}=a(\frac{y}{b})\)

\(\frac{U_{max}-U}{U_{max}-U_{min}}=b(\frac{y}{b})\)

\(\frac{U}{U_{max}}=c(\frac{y}{b})\)

\(\frac{U-U_{min}}{U_{max}-U_{min}}=d(\frac{y}{b})\)

Turbulent entrainment leads to ___________

Decrease in the magnitude of the velocity gradients in the cross-stream direction

Increase in the magnitude of the velocity gradients in the flow direction

Increase in the magnitude of the velocity gradients in the cross-stream direction

Decrease in the magnitude of the velocity gradients in the flow direction

Decrease in the magnitude of the velocity gradients in the cross-stream direction

The velocity of a free turbulent flow at any particular distance in the cross-stream direction is a function of ___________

The ratio of the distance in the cross-stream direction from the centreline and half-width at that cross section

The cross-stream velocity of the source

The velocity in the flow direction of the source

A turbulent jet is formed because ___________

A region of high-speed flow is surrounded by a stationary fluid

Interaction between an object and a fast moving fluid

Interaction of fast and slow moving fluids

10 + Mcqs in Free Wall Turbulence in Computational Fluid Dynamics Page 1 McqOptions

1.	The velocity at cross-stream of a turbulent wake is calculated using the formula\(\frac{U_{max}-U}{U_{max}-U_{min}}=b(\frac{y}{b})\) Note:Umax→ Maximum velocity at a particular cross-sectionUmin→ Minimum velocity at a particular cross-sectiony → Distance in the cross-stream direction from the centre line at the cross sectionb → Cross-stream half widthU → Velocity at the distance ‘y’The minimum velocity here corresponds to _____________
A.	Velocities at the edges
B.	Velocities just downstream of the object
C.	Velocities of the surrounding free stream
D.	Velocities at the centreline
Answer» C. Velocities of the surrounding free stream

Discussion

2.	The mean velocity gradient is zero at the centreline for ___________
A.	jets
B.	mixing flows
C.	mixing flows and wakes
D.	jets and wakes
Answer» E.

Discussion

3.	Which of these is correct for turbulent jets?Note:Umax → Maximum velocity at a particular cross-sectionUmin → Minimum velocity at a particular cross-sectiony → Distance in the cross-stream direction from the centre line at the cross sectionb → Cross-stream half widthU → Velocity at the distance ‘y’.
A.	\(\frac{U}{U_{max}-U_{min}}=a(\frac{y}{b})\)
B.	\(\frac{U_{max}-U}{U_{max}-U_{min}}=b(\frac{y}{b})\)
C.	\(\frac{U-U_{min}}{U_{max}-U_{min}}=c(\frac{y}{b})\)
D.	\(\frac{U}{U_{max}}=d(\frac{y}{b})\)
Answer» E.

Discussion

4.	If y is the distance in the cross-stream direction from the centre line at a particular cross-section b → Cross-stream half width. The mean velocity gradients and all the velocity fluctuations become zero when the value \(\frac{y}{b}\) ___________
A.	goes above unity
B.	goes below unity
C.	goes above zero
D.	goes below zero
Answer» B. goes below unity

Discussion

5.	Which of these is correct for mixing layer turbulent flows?Note:Umax → Maximum velocity at a particular cross-sectionUmin → Minimum velocity at a particular cross-sectiony → Distance in the cross-stream direction from the centre line at the cross sectionb → Cross-stream half widthU → Velocity at the distance ‘y’.
A.	\(\frac{U}{U_{max}-U_{min}}=a(\frac{y}{b})\)
B.	\(\frac{U_{max}-U}{U_{max}-U_{min}}=b(\frac{y}{b})\)
C.	\(\frac{U}{U_{max}}=c(\frac{y}{b})\)
D.	\(\frac{U-U_{min}}{U_{max}-U_{min}}=d(\frac{y}{b})\)
Answer» E.

Discussion

6.	Turbulent entrainment leads to ___________
A.	Increase in the magnitude of the velocity gradients in the flow direction
B.	Increase in the magnitude of the velocity gradients in the cross-stream direction
C.	Decrease in the magnitude of the velocity gradients in the flow direction
D.	Decrease in the magnitude of the velocity gradients in the cross-stream direction
Answer» D. Decrease in the magnitude of the velocity gradients in the cross-stream direction

Discussion

7.	The velocity of a free turbulent flow at any particular distance in the cross-stream direction is a function of ___________
A.	The ratio of the distance in the cross-stream direction from the centreline and half-width at that cross section
B.	The source velocity
C.	The cross-stream velocity of the source
D.	The velocity in the flow direction of the source
Answer» B. The source velocity

Discussion

8.	A turbulent jet is formed because ___________
A.	A region of high-speed flow is surrounded by a stationary fluid
B.	An object disturbs the flow
C.	Interaction between an object and a fast moving fluid
D.	Interaction of fast and slow moving fluids
Answer» B. An object disturbs the flow

Discussion

9.	Which of these terms represent the burst of turbulent activity to the outer region?
A.	Crisis
B.	Intermittency
C.	Turbulent burst
D.	Turbulent jumps
Answer» C. Turbulent burst

Discussion

10.	The process which is responsible for spreading of turbulent flows in the flow direction is __________
A.	Pluming
B.	Entrainment
C.	Turbulent mixing
D.	Turbulent generation
Answer» C. Turbulent mixing

Discussion

Explore topic-wise MCQs in Computational Fluid Dynamics.

The mean velocity gradient is zero at the centreline for ___________

If y is the distance in the cross-stream direction from the centre line at a particular cross-section b → Cross-stream half width. The mean velocity gradients and all the velocity fluctuations become zero when the value \(\frac{y}{b}\) ___________

Turbulent entrainment leads to ___________

The velocity of a free turbulent flow at any particular distance in the cross-stream direction is a function of ___________

A turbulent jet is formed because ___________

Which of these terms represent the burst of turbulent activity to the outer region?

The process which is responsible for spreading of turbulent flows in the flow direction is __________