Aerodynamics - Three-Dimensional Incompressible Flow Quiz(MCQ)

1 .

Is three dimensional source method is used for simulating incompressible potential flows?

A)

True

B)

False

C)

Can Not Say

D)

None of the above

Correct Answer : True

Explanation : A three dimensional source method for simulating incompressible potential flows around a deforming body without the kutta condition. A three dimensional source vorticity method that does not use the kutta condition is proposed.

2 .

Is three dimensional incompressible potential flows around a body accompanied by a wake vortex?

A)

True

B)

False

C)

Can Not Say

D)

None of the above

Correct Answer : True

Explanation : The three dimensional incompressible potential flows around a body accompanied by a wake vortex, surface singularity methods have been employed extensively owing to their ease of use and low solution times. In the case of vertical flow, the kutta condition is applied.

3 .

Is potential and current sources are defined at each node?

A)

True

B)

False

C)

Can Not Say

D)

None of the above

Correct Answer : True

Explanation : Potential and current source are defined at each node. In the three dimensional, each interior node is connected to the six surrounding nodes by impedance branches. Potentials and current sources are defines at each successive nodes.

4 .

Is three dimensional aerodynamic are considering irrotational, inviscid flow?

A)

False

B)

True

C)

Can Not Say

D)

None of the above

Correct Answer : True

Explanation : Three dimensional aerodynamics by considering the simple case of irrotational, inviscid flow. When compressibility can also be neglected, we consider a solution to Laplace’s equation in three dimensional just as in the two dimensional case.

5 .

Is wake vortex will produce around the three dimensional flow?

A)

True

B)

False

C)

Can Not Say

D)

None of the above

Correct Answer : True

Explanation : The three dimensional incompressible potential flows around a body accompanied by a wake vortex, surface singularity method have been employed extensively, owing to their ease of use and low solution times.

6 .

Is source and sink are equal?

A)

True

B)

False

C)

Can Not Say

D)

None of the above

Correct Answer : True

Explanation : The source and sink are equal but opposite strength located at points O and A, as sketched. The distance between the source and sink is l. consider an arbitrary point p located a distance r from the sink and a distance from the source, so source and sink are equal but opposite in strength.

7 .

Is three dimensional doublet is defined as the strength of the doublet?

A)

False

B)

True

C)

Can Not Say

D)

None of the above

Correct Answer : True

Explanation : The three dimensional doublet is defined as the strength of the doublet, compare equation with its two dimensional counterpart given in equation. Note that the three dimensional effects lead to an inverse squared variation.

8 .

Which of these flows is numerically computed using panel method technique?

A)

Anelastic flow

B)

Compressible flow

C)

Pseudo-incompressible flow

D)

Incompressible flow

Correct Answer : Incompressible flow

Explanation : Panel method is a technique that is used to numerically compute the inviscid, incompressible flow around any arbitrary body. The panel method incorporates laying panels of source/doublet/votices distribution over the body to obtain the aerodynamic properties.

9 .

Is three dimensional effect lead to an inverse squared variation?

A)

True

B)

False

C)

Can Not Say

D)

None of the above

Correct Answer : True

Explanation : The three dimensional effects lead to an inverse squared variation and introduce into the two dimensional case. The stream lines of this velocity field are sketched in the figure are the stream lines in the planes.

10 .

Is axisymmetric flow sometimes labeled as two dimensional flow?

A)

True

B)

False

C)

Can Not Say

D)

None of the above

Correct Answer : True

Explanation : The axisymmetric flow is sometimes labeled as two dimensional flow. However, it is quite different from the two dimensional planar flows discussed earlier. In reality, axisymmetric flow is degenerate three dimensional flow.

11 .

Which approximations are made in case of panel method in case of subsonic problems?

A)

Triangular panels with constant sink

B)

Quadrilateral panels with constant sink

C)

Quadrilateral panels with constant source strength

D)

Curved panels with constant source strength

Correct Answer : Quadrilateral panels with constant source strength

Explanation : In case of panel method, the entire body is approximated into several smaller quadrilateral panels having constant source strength. Although when the bodies get complex, higher order panel technique is used, which makes use of curved panels with variable source strengths.

12 .

In how many categories is the panel method grouped into?

A)

6

B)

4

C)

3

D)

2

Correct Answer : 2

Explanation : Panel method is generally divided into two categories-Surface panel method and mean-surface panel method. Surface panel method is more precise and accurate as the number of panels can be increased based on the complexity of the body.

13 .

Is uniform flow around a sphere is obtained?

A)

True

B)

False

C)

Can Not Say

D)

None of the above

Correct Answer : True

Explanation : Numerical solutions of the transient uniform flow around a sphere are obtained. The transition takes place between an initial potential flow and a fully developed viscous field. The fluid is incompressible and homogeneous around the sphere.

14 .

Is recirculatory wake appears at Re 1-1000?

A)

True

B)

False

C)

Can Not Say

D)

None of the above

Correct Answer : True

Explanation : The range of Reynolds number studied at Re 1-1000 .where a recirculatory wake appears and the nonlinear terms are essential, that is they cannot be neglected or approximated. The flow is assumed to be axisymmetric through this range.

15 .

Is vorticity transport is obtained by constructing a finite difference approximation?

A)

True

B)

False

C)

Can Not Say

D)

None of the above

Correct Answer : True

Explanation : The is obtained by constructing a finite difference approximation to the vorticity transport equation on an expanding spherical polar grid system. Central difference of second order accuracy both in time and space is utilized.

16 .

Which of these panels is distributed over a non-lifting body to analyze three-dimensional flow?

A)

Sink panel

B)

Source panel

C)

Vortex panel

D)

Doublet panel

Correct Answer : Source panel

Explanation : In case of non-lifting bluff bodies, source panels are distributed to analyze the three-dimensional potential flow unlike distribution of both vortex and source panels in case of lifting bodies.

17 .

Which of these panels is distributed over a lifting body to analyze three-dimensional flow?

A)

Sink panel

B)

Vortex panel

C)

Source panel

D)

Both source and vortex panels

Correct Answer : Both source and vortex panels

Explanation : Unlike non-lifting bodies which makes use of only source panel, lifting doies have a distribution of both source and vortex panels to assess the three-dimensional potential flow.

18 .

Is second order accuracy occurs at a time?

A)

True

B)

False

C)

Can Not Say

D)

None of the above

Correct Answer : True

Explanation : Central differencing of second order accuracy both in time and space is utilized. Experiments with numerical stability show an appreciable deviation from linearized stability analysis due to the large gradients of vorticity in the field.

19 .

Which of these distributions is required in the wake region of the lifting body?

A)

Sink

B)

Source

C)

Dipole

D)

Doublet

Correct Answer : Dipole

Explanation : Lifting bodies have a trailing edge which leads to a wake region. In the wake region, there is formation of vortices due to the disturbances in the flow. In this region, a dipole or vorticity singularity is used.

20 .

Which panels are used in case of higher-order panel method?

A)

Square panels

B)

Triangular panels

C)

Curved panels

D)

Quadrilateral panels

Correct Answer : Curved panels

Explanation : Higher-order panel method came into being when the panel method became computationally demanding for complex bodies. This method makes use of curved panels with variable source strength.

21 .

Is skin friction drag is formed due to pressure distribution?

A)

True

B)

False

C)

Can Not Say

D)

None of the above

Correct Answer : True

Explanation : The pressure distribution, skin friction, and drag as well as to understanding the changes in the wake organization and vortex dynamics with the Reynolds number. The unsteady turbulent flow is computed using detached eddy simulation.

22 .

Is large eddy simulation will occur for both subcritical and supercritical solution?

A)

True

B)

False

C)

Can Not Say

D)

None of the above

Correct Answer : True

Explanation : The large eddy simulation in the regions away from solid surfaces. For both the subcritical and supercritical solutions, the agreement with experimental measurements for the mean drag and pressure distribution over the sphere is adequate.

23 .

Which of these flows can be modelled by the panel method?

A)

Rotational flow

B)

Supersonic flow

C)

Compressible flow

D)

Incompressible flow

Correct Answer : Incompressible flow

Explanation : Panel method is idea for design analysis for only incompressible flows. It lacks the ability to model viscous flow, rotational flow w and supersonic flow. A panel method performs best when modeling fully-attached, high-reynolds-number (> 105), subsonic (Mach number < 1) flow.

24 .

Who developed the panel method?

A)

Ludwig Pradtl

B)

Hess and Smith

C)

Karl Wieghardt

D)

Theodore Von Karman

Correct Answer : Hess and Smith

Explanation : In order to model the wing section there were two methods used-Conformal mapping and Airfoil Theory. But these methods were not general and hence basic panel method was developed by Hess and Smith at the Douglas Aircraft Co. in the late 1950s and early 1960s.