Fluids Final
Homework 4
Continuity equations
A closed system is necessarily an isolated system
False
A closed system must be an isolated system
False
A control volume is fixed, identifiable quantity of mass that is isolated from its surroundings by boundaries
False
A fluid can be a liquid, but not a gas
False
A fluid is said to be static if there is no relative motion between adjacent particles
False
A frictionless flow is a viscous flow.
False
A fully-developed flow field in the x-direction means that the pressure is constant in the x-direction.
False
A large Reynolds number indicates that the flow is more likely to be laminar.
False
A magnetic force i an example of a surface force
False
A non-newtonian fluid has linear stress to strain relationship for a given applied shear stress
False
A streamline is a line joining all of the fluid particles that have passed through a fixed point in the flow field
False
A stress is a body force
False
A system cannot be both closed and isolated
False
A viscous fluid must flow very slowly when poured out of a can
False
All fluids are liquids
False
An incompressible fluid is expressed mathematically as rho = 0
False
An inviscid fluid is expressed mathematically as mu = 0 and rho = 0
False
An inviscid fluid is one where the viscosity is constant.
False
As you stir a pot of liquid mercury, you notice that it is hard to stir. This is, it resists your stirring action. This resistance comes entirely from the viscosity of the fluid
False
Density is an extensive property of a system since it is composed of mass and volume, which are both extensive properties
False
Ducts, nozzles, and diffusers are examples of external flows.
False
Enthalpy is an intensive property of a system
False
Flow through a duct system in a building is an example of a channel flow
False
For a steady flow situation, the timelines and streamlines are the same
False
For an unsteady flow situation, the curve representing the pathlines and streamlines are always the same, but the streamlines and streaklines are, in general, different
False
For an unsteady system, the volume flow rate in must equal the volume flow rate out of a control volume
False
For two-dimensional streamline coordinates, the positive n-direction points in a direction perpendicular to the flow direction and away from the convex side toward the concave side
False
For two-dimensional streamline coordinates, the positive n-direction points in a direction perpendicular to the flow direction and away from the convex side toward the concave side.
False
For two-dimensional streamline coordinates, the velocity component in the normal direction, Vn, is never zero (except at an inflection point in the curve)
False
Generally speaking, for an unsteady flow situation, only the pathlines and streaklines are the same
False
Geometric Similarity implies Kinematic Similarity.
False
Geometric similarity implies dynamic similarity.
False
Given an absolute pressure of 90 kPa and an atmospheric pressure of 100 kPa, the gage pressure is 10 kPa
False
Glycerin is an example of a non-newtonian fluid because its slow to pour out of a container
False
If a flow had friction, the total head (H) of the flow would increase.
False
If heat is added to a system and the temperature of a system increases, then the bulk kinetic energy of the system must always increase since the average speed of the molecules has increased
False
If the fluid is incompressible and the flow field is steady, then you can apply the steady Bernoulli equation between any two points on a streamline.
False
If we take the vorticity of the two-dimensional stream function, cz = vx - uy then it is always zero provided it is twice differentiable in x and y
False
Internal flows with viscosity generally have uniform velocity distributions.
False
Kinetic energy is an intensive property of a system
False
Liquid honey can be experimentally verified to be non-newtonian by showing that it pours more slowly than water out of a container
False
Mass is an intensive property of a system
False
Newton's second law of motion states that mass is conserved
False
Pipes with smaller diameters will have less head loss.
False
Stoke's Theorem states that the circulation around a closed contour is equal to the total viscosity within it.
False
Strictly speaking, a gas is not a continuum fluid because it is made up of discrete molecule with lots of space between them (the mean-free path); however, a liquid is a continuum because there is no space between the molecules in a liquid (they're touching)
False
The Hanquist number is a common dimensionless group, which is defined as the velocity of the flow divided by the speed of sound.
False
The Reynolds number is a ratio of pressure forces to viscous forces.
False
The concepts of closed and isolated in regards to a system are independent concepts
False
The continuity equation is derived from the conservation of momentum.
False
The continuity equation is the essential governing equation needed for studying head loss.
False
The continuity equation only applies to turbulent flows.
False
The continuity equation states that momentum is conserved
False
The drag coefficient has units of force.
False
The first law of thermodynamics states that the net force on an object is equal to the mass of the object multiplied by the acceleration of the object
False
The friction factor is only a function of the Reynold's number for turbulent flow.
False
The friction factor is only a function of the pipe roughness for a laminar flow.
False
The fundamental units for the British gravitational system are the slug, foot, and second
False
The fundamental units in the SI system corresponding to mass, length, and time are the gram, meter, and second
False
The hydrostatic equation would not be valid on the moon's surface where the acceleration due to gravity is less than that of earth's (assume the moon ha atmosphere)
False
The kinematic viscosity and dynamic viscosity must have the same dimensions since they both represent the stickiness of the fluid
False
The kinematic viscosity of a fluid is an extensive property of the fluid
False
The motion of a fluid particle can be decomposed into four basic components: kinetic energy, acceleration, momentum, and conservation of mass.
False
The static pressure is due to the bulk motion of the fluid.
False
The total head loss consists only of losses due to frictional effects in fully developed pipe flow.
False
The underlying principle that makes the hydrostatic equation valid is a balance between centripetal forces and gravity
False
Turbulent flow in a pipe is expected for Reynolds numbers less than 2300.
False
Velocity is an extensive property of a system
False
When you measure the air in your bike tire your tire gauge is measuring absolute pressure
False
Work is an extensive property of a system
False
Work is an intensive property of a system
False
You are stirring a pot of liquid mercury with a large paddle. You notice a strong resistance to the motion of the paddle from the liquid mercury. The resistance to the paddle's motion is solely due to the viscosity of the fluid
False
A benefit of differential analysis is that it can provide detailed information of the flow field (e.g. pressure and velocity distributions).
True
A closed system is also known as a control mass because no mass can escape the system
True
A control volume is a well-defined region in space that need not correspond to particular fluid particles
True
A dimension is a name given to any measurable quantity
True
A fluid in rigid-body rotation is experiencing shear forces, since the fluid particles are accelerating
True
A main difference between Euler's equations and Navier-Stokes equations is that Euler's equations are used for inviscid flows and Navier-Stokes are used for viscous flows.
True
A newtonian fluid is on the has a linear shear stress to shear strain-rate relationship
True
A normal stress on a static fluid's surface is also known as a pressure
True
A normal stress on a static fluid's surface is also known as pressure
True
A small Reynolds number indicates that the flow is more likely to be laminar.
True
A stress on a fluid particle's surface is defined as a force per unit surface area
True
A system is in steady state if its properties are independent of time
True
A system is said to be homogeneous if its properties are independent of space
True
A tangential stress on an object's surface is known as shear stress
True
A two-dimensional stream function is always constant along a streamline in steady flow.
True
A uniform flow field is independent of all space variables
True
All liquids are fluids
True
An example of fluid statics would be a thermometer
True
An irrotational flow has zero vorticity.
True
An isolated system is necessarily a closed system
True
An open system is a system where mass passes through the system
True
Any contact force that acts on an area of the surface of a fluid particle can be expressed as a stress
True
Archimedes's principle depends on the presence of a vertical pressure gradient
True
Archimedes's principle does not apply to "small" objects, such as the centimeter length scale of smaller. Assume the object is not so small that the continuum assumption fails to hold
True
Archimedes's principle states that a body immersed in a fluid is buoyed up with a force equal to the weight of the fluid displaced by the body
True
Consider a perfectly isolated piston-cylinder assembly that contains a gas. Take the gas to be our system. This system is an example of a closed isolated system
True
Crudely, a fluid is a substance that is easily deformable, and if poured into a container, it takes the shape of the container
True
Crudely, you can recognize a flowing liquid as laminar flow field if you inject a dye into the fluid and the flow looks very smooth and "glass-like"
True
Crudely, you can recognize when a fluid is turbulent if you inject a dye into the fluid and notice the flow field is very unsteady and "bubble" with lots of eddies swirling about, and the dye is quickly spread about and becomes unrecognizable in a short period of time
True
Dynamic similarity implies kinematic similarity.
True
Flow over a wing is an example of external flow
True
For a gas, the physical origins of the effect of viscosity on a small fluid particle of gas come from an exchange of momentum across the particle's boundary owing to random molecular motion plus a difference in bulk motion between the fluid particles and its environment
True
For a steady flow situation, the curve representing the pathlines, streamlines, and streaklines are all the same
True
For a steady system and incompressible flow, the volume flow rate in must equal the volume flow rate out of a control volume
True
For two-dimensional streamline coordinates, if the stream-lines are circular and the flow is steady, then the normal acceleration component, An, always points towards the concave side of the curve.
True
Gage pressure can be negative but absolute pressure can never be negative
True
Geometric similarity requires that the model and prototype be the same shape, and that all linear dimensions of the model be related to the corresponding dimensions of the prototype by a constant scale factor.
True
Head loss increases with flow rate
True
Head loss is typically due to friction.
True
If a fluid is assumed to be a continuum, the fluid's properties vary smoothly from point to point
True
If heat is added to a system and the temperature of a system increases, then the internal energy must always increase
True
If the fluid is incompressible and inviscid, and the flow field steady, then you can apply the steady Bernoulli equation between any two points on a streamline.
True
In a quasi-equilibrium process, the pressure in a system is approximately spatially uniform throughout the system at each moment in time
True
In a static fluid the only stresses present in the fluid are due to pressure
True
In order to properly define the temperature at a point in the flow field, we need the continuum assumption
True
In order to use the non-dimensionalization technique, you must know all of the governing equations and the boundary conditions for the system
True
In order to use the non-dimensionalization technique, you must know all of the governing equations and the boundary conditions for the system.
True
In the ideal gas model the internal energy, u, is a function of temperature alone
True
Inertial forces are fictitious forces that resists a change in velocity of an object.
True
Kinematic similarity implies geometric similarity.
True
Kinematic similarity is a necessary, but not sufficient, requirement for dynamic similarity.
True
Liquid honey and paint are examples of non-newtonian fluids
True
Loosely speaking, the viscosity of a fluid is the "stickiness" of the fluid
True
Mass is an extensive property of a system
True
Momentum is an extensive property of a system
True
Newton's second law of motion states that the net force on an object is equal to the mass of the object multiplied by the acceleration of the object
True
Paint is an example of a pseudoplastic in that it is a shear-thinning fluid
True
Particle linear deformation is related to volumetric strain
True
Particle rotation is related to angular velocity and vorticity
True
Pascal's law is one of the main underlying principles at work in hydraulic systems
True
Pascal's law states that if a gas is maintained at a constant temperature, then its volume will be inversely proportional to its pressure
True
Pascal's law states that pressure applied to an enclosed fluid is transmitted undiminished to every portion of the fluid and to the walls of the container
True
Pipe roughness, e, has units of length
True
Pressure is an intensive property of a system
True
Specific Volume is an intensive property of a system
True
Suppose the Buckingham Pi Theorem approach leads to one equation with one dependent non-dimensional parameter Π1, and two independent parameters, Π2 and Π3. Then, without knowing anything about the function itself, the resulting non-dimensional functional relationship is of the form: Π1=f(Π2,Π3).
True
Temperature is an intensive property of a system
True
The Buckingham Pi Theorem approach can be applied to situations where you don't know the explicit governing equations.
True
The Buckingham Pi Theorem approach requires experimental intervention to discover the functional relationship(s) between the parameters.
True
The Eulerian (or field) approach to describing fluid motion describes the flow field as a function of space and time
True
The Moody diagram relates pipe roughness, Reynold's number, and the friction factor.
True
The Reynolds number is a ratio of inertial forces to viscous forces.
True
The constant in the steady Bernoulli equation depends on the streamline that you're on (i.e., on the initial condition).
True
The continuum assumption for a fluid means that if the fluid was cut in half and in half again ad infinitum that the fluid's intensive properties, such as pressure and temperature, would be well defined in the limit at each point in space
True
The dynamic viscosity (mu) of a fluid has a fundamental SI units of kg/(m*s)
True
The equation F = 9.8m for the weight of an object is an example of a restrictive homogeneous equation
True
The equation W = int(P dV) is dimensionally consistent, where W = work, P = pressure, and V = volume
True
The equation v^2 = v0^2 + 2ax is dimensionally consistent
True
The equation x = t(v + 1/2at) is dimensionally consistent
True
The equation y = 4.9t^2 for a body falling from rest is an example of a restrictive homogeneous equation
True
The expansion of steam in a piston-cylinder is a situation well-suited for using a control volume analysis
True
The fundamental units in the SI system corresponding to mass, length, and time are the kilogram, meter, and second
True
The kinematic viscosity, when written in terms of the fundamental units, is independent of mass
True
The kinetic energy correction factor, α, is generally close to unity for turbulent flows.
True
The mathematical representation for an incompressible fluid is p (rho) is constant
True
The motion of a fluid particle can be decomposed into four basic components: translation, rotation, linear deformation, and angular deformation
True
The non-dimensionalization technique is most useful when you are able to identify characteristic properties of the flow field.
True
The parameters ρ, V, and L composing the inertia force term are idea candidates for repeated parameters since the inertia force shows up in so many non-dimensional parameters.
True
The shear-strain rate on an object is a measure of the object's rate of deformation to an applied shear force
True
The specific weight can be defined as g/v where g is gravity and v is the specific volume
True
The stagnation pressure (sometimes called total pressure) is essentially the sum of the static and dynamic pressures at a given location in the flow field.
True
The velocity field V = u(x,y)i + v(y)j is an example of planar flow
True
Turbulent flow is flow with fluctuating and disorderly motion.
True
Two flows are dynamically similar when the two flows have force distributions such that identical types of forces are parallel and are related in magnitude by a constant scale factor at all corresponding points.
True
Two flows are kinematically similar when the velocities at corresponding points are in the same direction and differ only by a constant scale factor.
True
Two-dimensional stream function is always constant along a streamline in steady flow
True
Volume is an extensive property of a system
True
Water flowing in a pipe is an example of an internal flow
True
Water flowing in a river is an example of a channel flow
True
When using the ideal gas law, you must use an absolute temperature scale
True
When you measure your body temperature in degrees Fahrenheit you are using a relative temperature scale
True
