CE 330 Concept Questions
True or False: A requirement for laminar flow near a flat plate is that the Reynold's number is greater than or equal to 3000
False
True or False: Component head loss is associated with fully developed flow in conduits, and it is caused by shear stresses that act on the flowing fluid.
False
True or False: Dynamic pumps function best at low discharge rates?
False
True or False: If pressure force is uniform all around the control surface then the net pressure force is equal to Mass*Acceleration
False
True or False: Pipe head loss is associated with fully developed flow in conduits, and is caused by shear stresses that act on the flowing fluid.
False
True or False: The Mass Flow rate equation is outflow-inflow
False
True or False: Turbulent Flow can be 1-D, 2-D, or 3-D
False
True or false? Does similitude have the same force that acts on corresponding masses in the model and the prototype?
False
True or false? In turbulent boundary layers the velocity profile is not uniform away from the wall.
False
True or False: Couette Flow involves flow of a viscous fluid between two surfaces, one of which moves tangentially to the other.
True
True or False: Pipe head loss is associated with flow through devices such as valves, bends, and tees.
True
True or False: The viscosity equation is useful for calculating the shear stress in a flowing fluid.
True
True or False: When calculating drag force you need to factor in all of the following: coefficient of drag force, the reference area, density and velocity.
True
True or false: Dimensional analysis is the process for applying pi-groups to analysis, experiment design, and the presentation of results.
True
True or false: The sum of forces on an object equal the rate of momentum out minus the rate of momentum in. (as long as there is no stored momentum within the CV)
True
True or False: In order for shear stress to occur a solid must be present to interact with the fluid.
False (technically, you can have shear stress between 2 immiscible fluids of different viscosities)
Which of the following is not an assumption made when Bernoulli's equation is used? a) the flow must be steady b) the flow must be incompressible c) viscous forces are not negligible d) none of the above
c) viscous forces are not negligible
The Reynold's number for turbulent flow over a flat plate is equal to: a) Re < 300,000 b) Re > 300,000 c) Re < 500,000 d) Re > 500,000
d) Re > 500,000
Which among the following is not a fundamental dimension? a) [L] b) [M] c) [T] d) [Kg]
d) [Kg]
Which one of the following options is not one of the four most important factors that influence drag force? a) shape of an object b) size of the object c) density of the fluid d) speed of the fluid e) these are all important factors
e) these are all important factors
The laminar boundary layer is a___ a) Smooth flow b) Rough flow c) Uniform flow d) Random flow
a) Smooth flow
Open channel flow in which the velocity is lower than the critical velocity and the water depth is higher than the critical depth is: a) Subcritical flow b) Supercritical flow c) Critical flow
a) Subcritical
Select all that apply: which of these statements is true about terminal velocity? a) maximum velocity attained by a falling body b) minimum velocity attained by a falling body c) occurs once the upward force(drag) equals the net downward force (weight minus buoyant force) d) it is a constant speed
a) maximum velocity attained by a falling body c) occurs once the upward force(drag) equals the net downward force (weight minus buoyant force) d) it is a constant speed
When is Q and W positive? Select all that apply. a)when work is done on surroundings b)when work is done on a system c)when energy is transferred into a system d)when energy is transferred out of a system
a) when work is done on surroundings c) when energy is transferred into a system
The specific energy within a channel that experiences a change in depth will be which of the following? a)E2 < E1 (depends on whether change in depth is an increase or decrease) b)E2 > E1 c)E2 = E1
a)E2 < E1 (depends on whether change in depth is an increase or decrease) b)E2 > E1
Circle all of the potential sources of head loss in conduit flow: a)Friction b)Contractions c)Pumps d)Sharp bends e)Valves
a)Friction b)Contractions d)Sharp bends e)Valves
Stability of a floating body depends on what? Circle all that apply: a)Position of the center of gravity b)Centroid of displaced fluid c)Center of buoyancy d)velocity e)Mass of object
a)Position of the center of gravity b)Centroid of displaced fluid c)Center of buoyancy e)Mass of object
Q: ___________ flow is flow that is driven by a moving wall. a) Unsteady Flow b) Couette Flow c) Non-Uniform Flow d)Uniform Flow
b) Couette Flow
If conditions for an upstream reservoir were not completely still or the pipe had vibration, the Reynolds number would be ________ than if conditions were ideal. a) Larger b) No Change c) Smaller d) Unknown
b) No Change
What is the main use of dimensional analysis is? a) To obtain the hydraulic and energy grade lines. b) To analyze model studies and correlate results. c) To obtain the energy equation and determine the type of flow. d) To convert units of energy, flow rate, and pressure.
b) To analyze model studies and correlate results
When analyzing an unknown flow in a pipe system, the engineers acquired a Reynolds number of 600,000. What type of flow is this? a) laminar b) turbulent c) viscous d) not enough information given.
b) turbulent
According to the Buckingham II theorem, how many dimensionless variables will there be if there are 5 variables and three primary dimensions? a) 5 b) 3 c) 2 d) 4
c) 2
Multiple choice: Which of the following is not correct regarding viscous flow over a flat surface? (Circle all that apply) a) Laminar boundary layer: Re<500,000 b) Laminar boundary layer: Re<300,000 c) Mixed boundary layer: Re>300,000 d) Mixed boundary layer: Re>500,000
c) Mixed boundary layer: Re>300,000
Which of the following is NOT an assumption the energy equation is based on: a) Steady state; no energy accumulation in CV. b) The CV has one inlet and one outlet. c) The flow must be irrotational d) Streamlines are straight and parallel at each section. e) All thermal energy terms (except for head loss) can be neglected.
c) The flow must be irrotational
During which types of flow is f influenced by wall roughness? a) Laminar flow b) Turbulent flow, smooth tube c) Transitionally rough turbulent flow d) Fully rough turbulent flow
c) Transitionally rough turbulent flow d) Fully rough turbulent flow
How do engineers design a scaled model that represents the real world condition? a) geometric similitude b) dynamic similitude c) Both a and b d) none of them above
c) both a and b
Reynold's number for turbulent conduit flow must be a) 1000 < Re < 3000 b) <3000 c) >3000 d) >5000
>3000
Which object shapes produce higher Drag Coefficients?
Blunt objects
True or False. The Buckingham Pi theorem states that the number of pi groups for a problem is equal to the number of basic dimensions minus the number of important variables.
False
How do different pipe shapes affect head loss and flow?
Different shapes have different surface contact with fluid so different friction losses.
(True or False) Assuming Bernoulli's equation applies for momentum relies on the pipe flow being laminar.
False
T/F. Open channel flow results from pressure differences within the channel
False
T/F: A Conduit is any pipe, tube or duct that is partially filled with a flowing fluid.
False
T/F: A Reynold's number of 2300 or less is considered turbulent?
False
T/F: A mixed boundary layer is a boundary layer that starts as Turbulent flow then transitions to Laminar flow.
False
T/F: A more viscous fluid will have a smaller μ
False
T/F: A pump takes energy away from a system.
False
T/F: Both solids and fluids resist force by deforming
False
T/F: For steady flow, velocity does change with time.
False
T/F: Form drag is a portion of drag force that is due to shear stress distribution
False
T/F: Free jets have a momentum force at the control surface.
False
T/F: Fully developed conduit flow is uniform and has a constant pressure gradient.
False
T/F: Gravity is a negligible force to assume when evaluating open channel flows
False
T/F: Gravity is a surface force
False
T/F: In Euler's equation, viscous forces are calculated.
False
T/F: Positive displacement pumps move fluid along by changing discharge.
False
T/F: Reynold's Transport Theorem can be used for any intensive property.
False
T/F: Subcritical flow occurs when the Froude number is greater than 1 and supercritical when the Froude number is less than 1.
False
T/F: The boundary layer is a region near the entrance to a conduit where the flow is not influenced by frictional forces.
False
T/F: The design of rotated/twisted buildings increases wind load and wind speeds
False
T/F: The direction of the force due to surface tension is perpendicular to the surface of liquid-gas interface
False
T/F: There exists a process that is 100% efficient.
False
What are the assumptions made when using Bernoulli's equation?
Inviscid fluid, steady flow
T/F The control volume is an Eulerian concept because it involves analysis of a region in space.
True
T/F: Dimensionless groups that are related to each other are called pi-groups.
True
T/F: Axial Flow pumps are best suited for high-discharge low-head applications.
True
T/F: Buoyant forces are caused by the hydrostatic pressure distribution.
True
T/F: Cavitation is when a liquid turns to a gas?
True
T/F: Drag is the component of force exerted by a fluid on an object in the stream wise direction.
True
T/F: For Lagrangian frame of reference, you are following the particle.
True
T/F: If the pressure force balances the acceleration forces, then a fluid is in hydrostatic equilibrium
True
T/F: In real fluids, viscous forces are never zero.
True
T/F: Poiseuille flow applies to steady, laminar, and fully developed flow of a Newtonian fluid with a Reynold's number less than 1000
True
T/F: Shear stress can be neglected in Inviscid Flow.
True
T/F: The lift force is the component of force perpendicular to the net free stream velocity when a body moves relative to a fluid.
True
T/F: The strong attraction between the molecules at the liquid surface creates membrane or skin
True
T/F: To utilize similitude between a model and prototype, both geometric and dynamic similitude is required.
True
T/F: Turbines extract energy from flowing fluid and pumps provide energy to flowing fluid.
True
T/F: When characterizing a fluid flow, the Lagrangian approach includes describing the fluid motion at various locations in space
True
T/F: sub-critical flow is referred to as tranquil flow?
True
True or False: The response of a Newtonian fluid to shear stress does not depend on the magnitude of shear stress
True
True or False: A conduit is a pipe, tube, duct that is completely filled with flowing fluid
True
True or False: An engineer can design a body shape to minimize the drag force. This process is called stream- lining and is often focused on reducing form drag.
True
T/F: for the momentum equation, velocity is uniformly distributed across the control surface.
True (for the version of the equation we have been using. Not required for the integral form)
What is a consequence of vortex shedding?
Vibration, heat dissipation.
Under which of the following conditions can you apply the Darcy-Weisbach equation? Select all that apply. a) Fully developed flow b) Steady flow c) Laminar flow d) Turbulent flow e) round pipes f) Non-round conduits
a) Fully developed flow b) Steady flow c) Laminar flow d) Turbulent flow e) round pipes
The boundary layer on a flat plate starts out as? a) Laminar b) Turbulent c) Neither
a) Laminar
Fill in the blank with the flow type that corresponds to the following Reynolds numbers for conduits: a)Re ≤ 2000 b)2000 ≤ Re ≤ 3000 c)Re ≥ 3000
a) Laminar b) Unknown c) Turbulent
Pressure is a: a) Scalar b) Vector
a) Scalar
Which of these are major assumptions for the energy equation? (answer is for the form of the energy equation we have worked with - the general, integral form contains no assumptions) a) Steady state; no energy accumulation in CV. b) The CV has one inlet and one outlet. c) Constant density flow. d) All thermal energy terms (except for head loss) can be neglected. e) Streamlines are stra ight and parallel at each section. f) Temperature is constant across each section. g) All of the above.
g) All of the above
Poiseuille flor or Hagen-Poiseuille Flor refers to ________ flow in a _______ tube. .
laminar....cylindrical. (or, in a rectangular channel where channel width >>height)
The maximum velocity attained by a falling body is called _________ velocity.
terminal
