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Fluid mechanics final exam questions and answers 2023
Q1. Incompressible fluid is defined as:
a) fluid, in which pressure is constant everywhere in the fluid
b) fluid, in which density is constant everywhere in the fluid
c) fluid, in which pressure at a point does not change with time
d) fluid, in which density at a point does not change with time
e) both b) and d)
Q2. Let’s assume that you are swimming in a swimming pool with your head just under the water
surface. Later, you dive to the bottom of the pool where you feel more pressure on your ears than near
the water surface. This is because:
a) density is larger at the bottom than the top
b) pressure is larger at the bottom than the top
c) according to linear momentum theory, a force will be generated due to the fluid moving around
your ears as you swim.
d) both a) and b)
e) both b) and c)
Q3. Fig. 1 shows the wake generated by a wind turbine. If this wake can be assumed to be a streamtube,
which edges are formed by a streamline, and if air at these low speeds can be assumed to be
incompressible, then which statement is true?
a) Since air cannot pass through the streamtube walls, only those air particles which entered the
streamtube through area A1 will pass through the wind turbine’s rotor disc (A) (Fig. 1a).
b) Since conservation of mass has to be maintained, particles passing through the wind turbine’s
rotor disc (A) must enter through an equal area (A2 = A) located at the streamtube entry plane
(Fig. 1b).
c) None of the above statements is true.
, 2
Fig. 1.
Q4. Consider a propeller surrounded by a Control Volume, as shown in Fig. 2. If we wish to calculate the
thrust generated by the propeller by applying the Linear Momentum theorem, then we would need to
know the following data:
a) velocity, pressure and density at the propeller disc only
b) the number and shape of propeller blades and the rotational frequency of the propeller
c) velocity, pressure and density at the propeller disc as well as the number and shape of the
propeller blades and the rotational frequency of the propeller
d) velocity, pressure and density at the inlet (station 1) and outlet (station 2) of the Control Volume
e) velocity, pressure and density at the inlet (station 1) and outlet (station 2) of the Control Volume
as well as the number and shape of the propeller blades and the rotational frequency of the
propeller.
Fig. 2. Side view of a propeller.
Q5. In essence, the Control Volume approach of analyzing fluid flows builds upon
a) the Lagrangian viewpoint of Fluid Mechanics
b) the Eulerian viewpoint of Fluid Mechanics
c) Pascal’s law
d) all of the above
e) none of the above
Fluid mechanics final exam questions and answers 2023
Q1. Incompressible fluid is defined as:
a) fluid, in which pressure is constant everywhere in the fluid
b) fluid, in which density is constant everywhere in the fluid
c) fluid, in which pressure at a point does not change with time
d) fluid, in which density at a point does not change with time
e) both b) and d)
Q2. Let’s assume that you are swimming in a swimming pool with your head just under the water
surface. Later, you dive to the bottom of the pool where you feel more pressure on your ears than near
the water surface. This is because:
a) density is larger at the bottom than the top
b) pressure is larger at the bottom than the top
c) according to linear momentum theory, a force will be generated due to the fluid moving around
your ears as you swim.
d) both a) and b)
e) both b) and c)
Q3. Fig. 1 shows the wake generated by a wind turbine. If this wake can be assumed to be a streamtube,
which edges are formed by a streamline, and if air at these low speeds can be assumed to be
incompressible, then which statement is true?
a) Since air cannot pass through the streamtube walls, only those air particles which entered the
streamtube through area A1 will pass through the wind turbine’s rotor disc (A) (Fig. 1a).
b) Since conservation of mass has to be maintained, particles passing through the wind turbine’s
rotor disc (A) must enter through an equal area (A2 = A) located at the streamtube entry plane
(Fig. 1b).
c) None of the above statements is true.
, 2
Fig. 1.
Q4. Consider a propeller surrounded by a Control Volume, as shown in Fig. 2. If we wish to calculate the
thrust generated by the propeller by applying the Linear Momentum theorem, then we would need to
know the following data:
a) velocity, pressure and density at the propeller disc only
b) the number and shape of propeller blades and the rotational frequency of the propeller
c) velocity, pressure and density at the propeller disc as well as the number and shape of the
propeller blades and the rotational frequency of the propeller
d) velocity, pressure and density at the inlet (station 1) and outlet (station 2) of the Control Volume
e) velocity, pressure and density at the inlet (station 1) and outlet (station 2) of the Control Volume
as well as the number and shape of the propeller blades and the rotational frequency of the
propeller.
Fig. 2. Side view of a propeller.
Q5. In essence, the Control Volume approach of analyzing fluid flows builds upon
a) the Lagrangian viewpoint of Fluid Mechanics
b) the Eulerian viewpoint of Fluid Mechanics
c) Pascal’s law
d) all of the above
e) none of the above
