FLUID DYNAMICS COMPREHENSIVE
EXAMINATION TEST 2026 COMPLETE
QUESTIONS AND CORRECT ANSWERS
◉How are the losses experienced in a pipe characterized for fluid
flow? How is head loss calculated?. Answer: Frictional losses can be
split into:
- Major losses: energy loss per length of pipe, such as due to surface
roughness
- Minor losses: energy lost due to pipe bends, valves, fittings,
entrance effects, etc.
Frictional major losses is known as head loss, which has the
equation: H = fLV^gD.
- f is the Darcy friction factor, which can be found using the Moody
chart, which can be used by knowing the Reynolds number and the
pipe roughness.
◉Describe the Eulerian vs Lagrangian approach to analyzing fluid
flow.. Answer: Lagrangian approach focuses on a packet of mass or
particle.
Eulerian approach focuses on a fixed window of space.
, ◉What is a streamline?. Answer: A streamline is a flow line whose
tangents show the velocity in the flow field.
◉Describe surface tension, what it does, its units/calculation, and
meaning. Answer: - Surface tension, denoted γ, is a measure of the
force at the interface between two immiscible fluids.
- Molecules of a fluid are attracted to each other due to cohesive
forces. A molecule at the surface of a fluid is missing half its
"neighbors" and therefore will feel an inward-pulling force. As such,
the surface is in tension and works to minimize surface area.
- It is calculated by γ = F/L with units N/m. This is visualized by a U-
shaped frame with a moving side; if a film is in this frame, surface
tension pulls inward on this side with force F.
◉Describe capillary action and how to find capillary rise.. Answer: -
Fluids have cohesive (due to electrostatic forces like polar covalent
bonds and van der Waals) and adhesive (due to
mechanical/chemical/dispersive mechanisms) forces.
- If a fluid's cohesive forces > adhesive forces, it will tend to cause a
liquid to go upward in a capillary, with an upward meniscus.
- If a fluid's adhesive forces > cohesive forces, it will tend to cause a
liquid to go downward in a capillary, with a downward meniscus.
If a capillary is placed in the fluid, the height of the fluid rise/sink
depends on Jurin's Law: h = 2γcosθ / ρgr_0.
EXAMINATION TEST 2026 COMPLETE
QUESTIONS AND CORRECT ANSWERS
◉How are the losses experienced in a pipe characterized for fluid
flow? How is head loss calculated?. Answer: Frictional losses can be
split into:
- Major losses: energy loss per length of pipe, such as due to surface
roughness
- Minor losses: energy lost due to pipe bends, valves, fittings,
entrance effects, etc.
Frictional major losses is known as head loss, which has the
equation: H = fLV^gD.
- f is the Darcy friction factor, which can be found using the Moody
chart, which can be used by knowing the Reynolds number and the
pipe roughness.
◉Describe the Eulerian vs Lagrangian approach to analyzing fluid
flow.. Answer: Lagrangian approach focuses on a packet of mass or
particle.
Eulerian approach focuses on a fixed window of space.
, ◉What is a streamline?. Answer: A streamline is a flow line whose
tangents show the velocity in the flow field.
◉Describe surface tension, what it does, its units/calculation, and
meaning. Answer: - Surface tension, denoted γ, is a measure of the
force at the interface between two immiscible fluids.
- Molecules of a fluid are attracted to each other due to cohesive
forces. A molecule at the surface of a fluid is missing half its
"neighbors" and therefore will feel an inward-pulling force. As such,
the surface is in tension and works to minimize surface area.
- It is calculated by γ = F/L with units N/m. This is visualized by a U-
shaped frame with a moving side; if a film is in this frame, surface
tension pulls inward on this side with force F.
◉Describe capillary action and how to find capillary rise.. Answer: -
Fluids have cohesive (due to electrostatic forces like polar covalent
bonds and van der Waals) and adhesive (due to
mechanical/chemical/dispersive mechanisms) forces.
- If a fluid's cohesive forces > adhesive forces, it will tend to cause a
liquid to go upward in a capillary, with an upward meniscus.
- If a fluid's adhesive forces > cohesive forces, it will tend to cause a
liquid to go downward in a capillary, with a downward meniscus.
If a capillary is placed in the fluid, the height of the fluid rise/sink
depends on Jurin's Law: h = 2γcosθ / ρgr_0.
