# Theory-based Quiz

#### Total number of Questions - 45

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Basics of Fluid Dynamics

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1 / 44

Using the Stokes' approximation, you were asked to calculate the non-dimensional drag coefficient for a creeping flow around a cylinder (under 2D assumptions). What do you find out?

2 / 44

What is the correct value of Poiseuille number for laminar flows in round pipes?

3 / 44

$1/5^{th}$ model of car is tested in a wind tunnel. For the flow over the test model to be dynamically similar to that of the full-scale car, the wind tunnel velocity for the model must be: [Hint: both the model and full-scale car are being tested in the same wind-tunnel].

4 / 44

Which of the following theorems can be used to transform the governing equations from the Lagrangian framework to the Eulerian framework?

5 / 44

An isothermal incompressible fluid flows through a perfectly insulated coiled tube. To describe the problem, how many unknowns need to be solved for from the system of equations ?

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We wish to use CFD to model the air flow around a car. The car is travelling north at a speed of $60$ $mph$. The wind is blowing south with wind speeds of $10$ $mph$. What inlet boundary velocity value should be used?

7 / 44

The force that acts tangential to the surface of a body moving through a fluid is called

8 / 44

To be considered a continuum fluid flow, the value of Knudsen number should be

9 / 44

Consider the manometer shown in the picture. The pressure difference $\Delta p$ is equal to:

10 / 44

An american football is flying horizontally in air. The plot shows the pressure contours of the ball moving from right to left. In which region is the wake located?

11 / 44

In a pitot tube mounted on an aircraft, what is the difference between the total and static pressures inside the total pressure tube?

12 / 44

Which of the following is a non-intrusive (i.e. the measurement process does not disturb the flow) method of measuring temperature?

13 / 44

An altimeter uses _______ to measure altitude.

14 / 44

For a fluid, the relationship between shear stress and velocity gradients is given by _______, where $\tau=$ shear stress, $\mu=$ dynamic viscosity, $u$ is flow velocity, $y$ is the wall normal distance

15 / 44

A static pitot tube is a probe that contains two openings - at the tip and on the side (as shown in the image). The tip and side openings respectively measure the following physical quantities:

16 / 44

What’s an example of a solid behaving like a fluid?

17 / 44

An american football is flying horizontally in air. The plot shows the pressure contours of the ball moving from right to left. Which region has the lowest pressure?

18 / 44

For a fluid flow to be considered a steady flow, it must be:

19 / 44

The sensor connected to the pitot tube on a racing car is sending a record of increasing total pressure values, while the static pressure is constant. This means that the car is

20 / 44

Which of the following is the correct expression for friction factor for laminar flows in round pipes? ($Re_{D}=\frac{\rho \bar{u}D}{\mu}$)

21 / 44

Fluid statics can be used for ______

22 / 44

The surface forces acting on a fluid parcel comprise of?

23 / 44

An airplane is traveling at a Mach Number = $2$. This means the airplane is traveling at the speed which is _______ times the local speed of sound.

24 / 44

Consider the barometer shown in the picture. If the atmospheric pressure decreases, then the height $h$:

25 / 44

In the case of 2D Poiseuille flow in a 2D planar channel, the maximum velocity occurs at:

26 / 44

When comparing with experiments, the validity range of Oseen's approximation for low Reynolds number flows was found to be _____

27 / 44

What is a reasonable simplifying modeling assumption for a water flow through a coiled tube?

28 / 44

In the conservation of mass equation shown below, which of the following terms is always zero under the incompressible flow assumption

$\partial\rho/\partial\ t+\partial(\rho\ u)/\partial\ x+\partial(\rho\ v)/\partial\ y+\partial(\rho\ w)/\partial\ z=0$

29 / 44

The following measurement technique is applicable for measuring velocity :

30 / 44

Which of the following statements are true in the context of an aircraft stall?

31 / 44

The fundamental physical dimensions used in fluid dynamics are:

32 / 44

A system can be considered as an open system when :

33 / 44

Consider the barometer shown in the picture. In order to maintain the same height $h$ for the same atmospheric pressure, on a planet with twice the gravitational acceleration, we could:

34 / 44

When a force is applied to both a solid and fluid, which of the following is true?

35 / 44

Consider an aircraft flying horizontally at an altitude of $8\ km$ with a speed of $250\ m/s$. The lift force is ______ with respect to the direction of motion of the aircraft.

36 / 44

Which of the following equations is the conservation of energy in the Lagrangian framework?

37 / 44

In a vertical circular water pipe $3\ m$ long with constant diameter ($D = 1\ cm$), water is flowing from inlet (bottom) to outlet (top), in a direction opposite to the gravitational force. The static pressure at the inlet is $101\ kPa$ and inlet velocity is $0.001\ m/s$. Assuming water as an incompressible fluid, the static pressure at the outlet:

38 / 44

For a 3D isothermal viscous fluid flow, if compressibility and heat transfer are not considered, which of the following equations can be avoided from solving?

39 / 44

What does the Reynolds Number physically represent?

40 / 44

The peak of Mount Everest is at an altitude of $8.84$ $km$ above sea level. To reach the summit, climbers trek through the Everest base camp, which is at an altitude of $5.4$ $km$ above the sea level. Assuming an isothermal atmosphere (temperature, $T$), what is the ratio of atmospheric pressures at the summit to that of the base camp.

41 / 44

Lift force on a body is influenced by which of the factors?

42 / 44

Brinkman Number is defined as the ratio of

43 / 44

Two different fluids ($A$ and $B$) are flowing through different pipes. The pressure readings from manometers attached near the outlet ends (point $1$) of each pipe is the same. The two fluid velocities (local to point $1$) in each pipe are also equal. If the density of fluid $A$ is four times that of fluid $B$, the total pressure experienced by fluid $B$ is ___________ compared to fluid $A$. (Assume that the hydrostatic term is the same at the outlets)

44 / 44

If the Prandlt number of a fluid is greater than $1$, this means that the thermal diffusion in the fluid is _________ compared to the momentum diffusion.