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RES120
Oxygen Therapy
204
Health Care
Undergraduate 2
08/27/2008

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Cards

Term
Describe the three states of matter
Definition
solid liquid and gas
Term
What is vaporization
Definition
the change of state from liquid to gas
Term
What does vaporization require in order to change from a liquid to a gas
Definition
"heat energy and according to the First Law of Thermodynamics, this heat energy must come from the surroundings"
Term
Explain evaporation
Definition
"a type of vaporization whereby heat is taken from the air surrounding the liquid thereby cooling the air - i.e. sweat evaporation which cools of the body by transferring the body's heat to water, which is a good conductor of heat and transferring that heat into the surrounding air"
Term
What is condensation
Definition
The opposite of evaporation whereby a gas turns back to a liquid. condensation gives heat back to the surroundings
Term
What happens to kinetic energy when a solid is heated
Definition
it increases and this added internal energy increases molecular vibrations
Term
How is a solid changed into a liquid
Definition
"kinetic energy increases and this added internal energy increases molecular vibrations and if enough heat is applied then the intermolecular attractive forces weaken adn at some point, molecules will break free of their rigid structure and the solid will change into a liquid"
Term
What is the extra heat needed to change a solid to a liquid
Definition
latent heat of fusion
Term
What does all matter posess and what is it called?
Definition
energy and it is called internal energy
Term
What are the two major types of internal energy
Definition
energy of position which is potential energy and energy of motion which is kinetic energy
Term
What is most internal energy in solids and liquids
Definition
"although all matter has some kinetic energy, most internal energy in solids and liquids is potential energy"
Term
What is the potential energy within solids and liquids a result of
Definition
strong attractive forces between molecules. These intermolecular forces cause rigidity in solids and cohesiveness and viscosity in liquids
Term
What is the internal energy of gases
Definition
most of their internal energy is kinetic....the attractive forces are week and the molecules are moving all the time
Term
What is the relationship between temperature and kinetic energy?
Definition
"The temperature of a gas, with most of its internal energy spent keeping molecules in motion, is directly proportional to its kinetic energy whereas the temperature of solids and liquid represent only part of their total internal energy"
Term
What is the international temperature scale?
Definition
SI (systeme internationale) with zero Kelvin
Term
How many degrees are there between freezing and boiling?
Definition
100 making it a centrigrade scale or 100 step scale
Term
What is the difference between kelvin and celcius scales?
Definition
"In Kelvin, 0 degrees is as close to absolute zero as possible whereas 0 celcius is freezing point of water. celcius also has a 100-step system with 100 degrees between freezing and boiling"
Term
What is absolute zero?
Definition
The temperature with which kinetic molecular activity stops
Term
what is the absolute zero temperature on the celcius scale
Definition
-273
Term
How is kelvin converted to celcius?
Definition
subtract 273
Term
How is celcius converted to kelvin
Definition
add 273
Term
What is absolute zero on the Fahrenheit scale
Definition
-460
Term
What is the formula to convert Fahrenheit to Celcius
Definition
C=5/9 (f-32)
Term
How do you convert celcius to Fahrenheit
Definition
f=(9/5xC)+32
Term
What is the First Law of Thermodynamics
Definition
energy can be neither created nor destroyed
Term
"What happens if a substance gains or loses energy, based on the first law of thermodynamics"
Definition
"any energy a substance gains must exactly equal the energy lost and if a substance loses energy, this loss must be offset by an equal gain in the energy of its surroundings"
Term
What is the formula for the first law of thermodynamics
Definition
"U=E+W U is internal energy of an object, E is the energy transferred to or from and W is the external work perfomed on the object"
Term
"In the forumla for the first law of thermodynamics, what is E, or energy, equivalent to?"
Definition
"heat because heating is the transfer of internal energy from a high-temperature object to a low-temperature object. based on this formula, you can increase the internal energy of an object by heating it or by performing work on it"
Term
What does the first law of thermodynamics tell us regarding when two objects exist at different temperatures
Definition
heat will move from the hotter object to the cooler object until the objects' temperatures are equal. two objects with the same temperature exist in thermal equilibrium
Term
What are the four ways heat transfer can be affected
Definition
"conduction, convection, radiation and evaporation/condensation"
Term
How does heat transfer in solids mainly occur
Definition
via conduction which is the transfer of heat by direct contact between hot and cold molecules
Term
What is conduction heat dependent upon
Definition
it depends on both the number and force of molecular collisions between adjoining objects
Term
how is heat transfer beween objects quantified by
Definition
using a measure called thermal conductivity
Term
Which types of substances have high thermal conductivity and which have lower ones?
Definition
"metals - transfer heat rapidly therefore if you touch metal like silver, copper, aluminum, iron, lead, etc. it feels cold because the object is ""taking"" your heat. vs. solids and liquids exhibit low thermal conductivity - air, wool cork board, fiberglass all have low thermal conductivity with ice, glass, concrete, water, hydrogen, helium, snow all in the middle"
Term
How is heat transferred in both liquids and gases
Definition
mainly by convection which involves the mixing of fluid molecules at different termperatures. air (even though poor conductor of heat) can transfer heat by convection by being warmed in one location and then circulated to carry heat elsewhere
Term
solid
Definition
"solid internal order, molecules move less and maintain shape because atoms are kept in place by strong mutual attractive forces called van der waals forces"
Term
Liquid
Definition
"mutual attraction but much weaker than solids, molecules move about freely which explains why they take shape of container and are capable of flow, liquids are similar to solids in that they are dense and cannot easily be compressed"
Term
gas
Definition
"molecular attractive forces are weak, lack restriction to movement, exhibit rapid, random motion with frequent collisions. No inherent boundaries, easily compressed and expanded and they can flow. "
Term
Which two states of matter are considered fluids
Definition
liquids and gases because gases and liquids can both flow
Term
What are fluid movements carrying heat energy called
Definition
convection currents
Term
how does radiant heat transfer
Definition
It transfers without direct contact and occurs even when in a vacuum such as the sun heating the earth
Term
How is radiant energy similar to that of light
Definition
"radiant energy given off by objects at room temperature is mainly in the infrared range, which is invisible to the human eye. Whereas objects such as an electrical stove burner or a kerosene heater radiate some of their energy as visible light. Commonly used to keep newborn infants warm."
Term
What is the formula that defines the rate at which an object gains or loses heat by radiation
Definition
E/t=ekA(T2-T1)
Term
"In the radiation energy equation (E/t=ekA(T2-T1) what is E/t, what is e, k, A, T1, T2"
Definition
"E/t is heat loss or gain per unit time, e is the emissivity of the object or its relative effectiveness in radiating heat. k is StefanBoltzmann constant (based on mass and surface area) A is the area of the radiating object and T1 and T2 are temperatures of environment and object respectively - for an object with a given emissivity (relative effectiveness in radiating heat) the larger the surface area and the lower the surrounding temperature, the greater is the radiant heat loss per unit time"
Term
What does freezing do with regard to energy to the surroundings
Definition
"just as melting requires large amounts of externally applied energy, you would expect freezing to return this energy to the surroundings"
Term
What does the First Law of Thermodynamics say about energy required to freeze and melt a substance
Definition
That they must equal each other and therefore the freezing and melting points of a substance are the same
Term
What is buoyancy
Definition
variations in liquid pressure within a container producing upward supporting force
Term
"What helps explain viscosity, capillary action and surface tension"
Definition
"although melting weakens intermolecular bonding forces, liquid molecules still attract one another adn the persistence of these cohesive forces among liquid molecules explain the physical properties of viscosity, capillary action and surface tension"
Term
What does the pressure exerted by a liquid depend on
Definition
both its height (depth) and weight density (weight per unit volume)
Term
what is the equation form of pressure exerted by a liquid
Definition
PL=h x dw
Term
pL=h x dw - what do the letters stand for
Definition
"pL is statis pressure exerted by the liquid, h is the height of the liquid column, and dw is the liquid's weight density"
Term
What is Pascal's principle
Definition
liquid's pressure acts equally in all directions
Term
What is Archimede's principle
Definition
buoyancy - liquids exert buoyant force because the pressure below a submerged object always exceeds the pressure above it and this difference in liquid pressure creates an upward or supporting force. This buoyant force must equal the weight of the fluid displaced by the object
Term
How is the buoyant force calculated as with B being buoyant
Definition
B=dw * v
Term
What happens if the weight density of an object is less than that of water
Definition
It will displace a weight of water greater than its own weight and the buoyant force will overcome gravity and the object will float
Term
What happens if the weight density of an object is greater than that of water
Definition
it will sink
Term
How is Achimides' principle used in the clinical setting
Definition
It is used to measure the specific gravity of certain liquids
Term
What helps keep solid particles suspended in gases
Definition
"buoyancy. these suspensions, called aerosols, are important in the role of the respiratory therapist"
Term
What is viscocity
Definition
the force opposing a fluid's flow
Term
What is a fluid's viscocity in direct proportion to
Definition
"the cohesive forces between its molecules. the stronger these cohesive forces, the greater is the fluid's viscosity. the greater a fluid's viscosity the greater is its opposition to flow"
Term
When is viscosity most important
Definition
when fluids move in discrete cylindrical layers called streamlines
Term
What is a pattern of motion whereby fluids move in discrete cylindrical layers called streamlines
Definition
laminar flow
Term
What does laminar flow consist of
Definition
concentric layers of fluid flowing parallel to the tube wall at velocities that increase toward the center
Term
What is the difference in velocity of the layers within laminar flow called
Definition
the shear rate
Term
"What is the shear rate, the difference in velocity of the layers within laminar flow a measure of"
Definition
how easily the layers separate
Term
How easily the layers of shear rate separate are dependent upon which two factors
Definition
the pressure pushing or driving the fluid called the shear stress and the viscosity of the fluid
Term
"In uniform fluids such as water or oil, how is viscosity related to temperature"
Definition
the viscosity varies with temperature
Term
why does viscosity vary with temperature in uniform fluids
Definition
"because higher temperatures weaken the cohesive forces between molecules, heating a uniform fluid lowers viscosity. a lower temperature increases its viscosity (like a car engine in the morning, the oil is too viscous to move through the engine)"
Term
How much higher is the viscosity of blood compared to water and why
Definition
blood has a viscosity approximately five times greater than water because blood is a complex fluid that contains not only liquid but cells in suspension
Term
Why does the heart work harder to pump blood than it would if it were pumping water
Definition
becasue the heart must perform more work if when blood viscosity increase as occurs with polycythemia
Term
What is the attractive force between like molecules called
Definition
cohesion
Term
what is the attractive force between unlike molecules
Definition
adhesion
Term
How can the forces of adhesion and cohesion be observed
Definition
by placing a liquid in a small-diameter tube where the top of the liquid forms a curved survace or meniscus. when the liquid is water the meiscus is concave because the water molecules at the surface adhere to the glass more strongly than they cohere to each other but mercury meniscus is convex because the cohesive forces pulling the mercury atoms together exceed the adhesive forces trying to attract the mercury to the glass
Term
What is surface tension
Definition
a force exerted by like molecules at a liquid's surface
Term
What is surface tension quantified by?
Definition
"measurement of the force needed to produce a ""tear"" in a fluid surface layer."
Term
"For a given liquid, how does surface tension vary?"
Definition
"It varies inversely with temperature thus, the higher the temperature, the lower is the surface tension"
Term
What does surface tension do the the pressure inside a ball?
Definition
"like a fist compressing a ball, surface tension increases the pressure inside a liquid drop or bubble. Laplace's Law states that this pressure varies directly with the surface tension of the liquid and inversely with its radius."
Term
What plays a key role in the mechanics of ventilation
Definition
"because the lungs alveoli resemble clumps of bubbles, it follows that surface tension plays a key role in teh mechanics of ventilation"
Term
What does abnormality of alveolar surface tension result in?
Definition
Collapse of alveoli due to high surface tension
Term
What is capillary action
Definition
"a phenomenon in which a liquid in a small tube moves upward, against gravity"
Term
What two forces does capillary action involve?
Definition
both adhesive and surface tension forces
Term
What does the adhesion of water molecules to the walls of a thin tube cause
Definition
an upward force on the liquid's edges and produces a concave meniscus
Term
"Because surface tension acts to maintain the smallest possible liquid-gas interface, instead of just the edges of the liquid moving up, what happens"
Definition
the whole surface is pulled upward
Term
What are two applications of capillary action?
Definition
the basis for blood samples obtained by use of a capillary tube adn the absorbent wicks used in sme gas humidifiers
Term
What are the two forms of vaporization
Definition
boiling and evaporation
Term
What is the boiling point of a liquid
Definition
the temperature at which its vapor pressure equals atmospheric pressure
Term
What happens to its molecules when a liquid boils
Definition
its molecules must have enough kinetic energy to force themselves into the atmosphere against the opposing pressure
Term
What causes a greater boiling point
Definition
"because the weight of the atmosphere retards the escape of vapor molecules, the greater the ambient pressure, the greater is te boiling point"
Term
What happens to the boiling point when atmospheric pressure was low
Definition
"liquid molecules escape more easily, and boiling occurs atlower temperatures "
Term
WHat is the energy required to vaporize a liquid
Definition
the latent heat of vaporization
Term
what is the number of calories required to vaporize 1 g of a liquid at its normal boiling point
Definition
latent heat of vaporiztion
Term
Why does vaporization require more energy than melting
Definition
melting weakens attractive forces between molecules but vaporization eliminates them. elimination of these forces converts essentially all of a substances' internal energy into kinetic energy
Term
What is evaporation
Definition
a liquid can change into a gas at temperatures lower than its boiling point
Term
"when at temperatures lower than the boiling point, how does water enter the atmosphere?"
Definition
"through evaporation. the liquid molecules are in constant motion, as in the gas phase. although this kinetic energy is less intense than in the gaseous state, it allows some olecules near the surface to escape into the atmosphere"
Term
what is the invisible gaseous form of water called and which other forms is it distinguished from
Definition
molecular water vs visible particulate water such as mist or fog
Term
Molecular water obeys the same physical principles as other gases and therefore exerts a pressure called what
Definition
water vapor pressure
Term
does evaporation require heat
Definition
"yes - the heat energy required for evaporationn comes from the air next to the water surface. As the surrounding air loses heat energy, it cools. This is the principle of evaporation cooling"
Term
What happens to water vapor molecules inside a closed container
Definition
"it continues to enter the air unti it can hold no more water. At this point, the air over the water is saturated with water vapor. vaporization does ot stop once saturation occurs. instead, for every molecule escaping into the air, another returns to the water reservoir. These conditions are referred to as a state of equilibrium"
Term
What factor influences evaporation the most
Definition
temperature
Term
WHat two ways does temperature affect evaporation
Definition
"the warmer the air, the more vapor it can hold therefore the capacity of air to hold water vapor increases with temperature. the warmer the air contacting a water surface, the faster is the rate of evaporation. second, if water is heated its kinetic energy is increased and thus more molecules are helped to escape from its surface. 1-capcity to hold molecular water is increased 2 - water vapor pressure is increased"
Term
What does water vapor pressure represent
Definition
the kinetic activity of water molecules in air
Term
What is absolute humidity
Definition
measured by weighing the water vapor extracted from air using a drying agent
Term
What is relative humidity
Definition
the ratio of its actual water vapor content to its saturated capicity at a given temperature
Term
"At 100% relative humdity, what does even slight cooling of gas cause?"
Definition
the water vapor to return back to a liquid state called condensation which deposits on any available surface which could even include particles suspended in the gas
Term
What does condensation do with regard to temperature
Definition
"returns heat to and warms the surrounding environment, whereas vaporization of water cools teh adjacent air"
Term
What is the temperature at which condensation begins
Definition
the dew point
Term
what happens if a saturated gas is cooled below its dew point
Definition
it causes increasingly more water vapor to condense into liquid water droplets
Term
What is the influence of pressure on vaporization
Definition
"if the surrounding air pressure is high, there will be more opposing air molecules and vaporization will decrease"
Term
WHat is the influence of surface area on a gas
Definition
"The greater the available surface area of the gas in contact with air, the greater is the rate of liquid evaporation. i.e. dry air water on flat plate vs. moist air and liquid in a glass"
Term
What properties of gases are shared with liquids and how are gases different?
Definition
"gases exert pressure, are capable of flow and exhibit the property of viscosity. unlike liquids, gases are readily compressed and expanded and fill the spaces available to them through diffusion"
Term
Why is most of a gas's internal energy kinetic energy
Definition
because a gas's intermolecular forces of attraction are so weak
Term
WHat is the velocity of gas molecules directly proportional to
Definition
temperature
Term
what happens as a gas is warmed
Definition
"its kinetic activity increases, its molecular collisions increase, and its pressure rises. when a gas is cooled, molecular activity decrees, particle velocity and collision frequency decline, and the pressure drops"
Term
What is Avogadro's Law
Definition
"states that 1 g atomic weight of any substance contains exactly the same number of atoms, molecules, or ions. "
Term
what is STPD
Definition
standard temperature and pressure dry
Term
what is the ideal molar volume of any gas at standard temperature and pressure dry (STPD)
Definition
22.4 L
Term
What is density
Definition
the ratio of a substance's mass to its volume. dense substance has heavy particles packed closely together. and a low density substance has a low concentration of light atomic particles er unit volue.
Term
what is a good high and low density gas example
Definition
high density - uranium and low density - hydrogen
Term
"In the clinical setting, what is often substituted for mass?"
Definition
weight and thus weight density is actually measured
Term
what is the most common unit of weight density in gases
Definition
grams per liter
Term
What does weight density equal
Definition
weight divided by volume
Term
What is diffusion
Definition
the process whereby molecules move from areas of high concentration to areas of low concentration
Term
what is the driving force behind diffusion
Definition
kinetic energy because gases have high kinetic energy so they diffuse most rapidly
Term
"Besides gases, where else does diffusion occur"
Definition
in liquids and sometimes solids
Term
How are gas diffusion rates quantified
Definition
graham's law - diffusion of a gas is inversely proportional to the saquare root of its gram molecular weight
Term
what will quicken diffusion
Definition
anything that increases molecular activity therefore heating and mechanical agitation
Term
what do all gases exert
Definition
pressure
Term
"in physiology, what is the term often used to refer to pressure exerted by gases when dissolved in liquid"
Definition
tension
Term
what does a gases tension or pressure depend on
Definition
mainly on its kinetic activity
Term
HOw does gravity affect gas pressure
Definition
"increases gas density, thereby increasing the rate of molecular collision and gas tension"
Term
what is pressure the measure of
Definition
force per unit area
Term
How can pressure be measured indirectly
Definition
"as the height of a column of liquid, as is commonly done to determine atmospheric pressure"
Term
what device is used to measure atmospheric pressure
Definition
barometer
Term
what does a barometer consist of
Definition
an evacuated glas tube appox 1 m long. its closed at the top end and the lower end is immersed in a mercury reservoir. the pressur eof the atmosphere on the mercury forces mercury u the vacuum tube a distance equivalent to the force exerted. the height of the mercury column represents the downward force of atmospheric ressure. barometer pressure is reported with readings such as 30.4 inches of mercury or 772 mm hg which means the atmospheric pressure is great enough to support a column of mercury 772 mm hg tall
Term
what is torr
Definition
a term alternatively used in pressure readings and is short for torricelli - seventeenth century inventor of the mercury barometer
Term
what does 1 torr equal in mm hg
Definition
1 torr is the same as 1 mm hg
Term
what affects a barometers mercury level besides pressure
Definition
temperature
Term
what must be corrected for accuracy in a barometer pressure reading
Definition
temperature
Term
who provides temperature correction factors for barometric pressure readings
Definition
US Weather Bureau
Term
what kinds of columns are used in clinical practice
Definition
"predominantly mercury, some water columns used in low pressure situations"
Term
What are water and mercury columns being replaced with for the measurement of pressure
Definition
electronic and mechanical devices
Term
what must a mechanical or electronic device be measured against in order to be properly calibrated for pressure measurement
Definition
against a mercury or water column
Term
what is the simplest mechanical pressure gauge
Definition
aneroid barometer and it consists of sealed evacuated metal box with a flexible spring-supported top that responds to external pressure changes. this motion activates a geared pointerwhich provides a scale reading analogous to pressure
Term
what is a strain-gauge pressure transducer
Definition
"flexible chamber that can be used to measure pressure electronically. pressure changes expand and contract a flexible metal diaphragm connected to electrical sires. the physical strain on the diaphragm changes the amount of electricity flowing thourgh the wires. by measuring this change in electrical flow, we are indirectly measuring changes in pressure"
Term
what is partial pressure
Definition
the pressure exerted by a single gas in a mixture
Term
what does dalton's law describe with regard to the total pressure in a gas mixture
Definition
the relationship among the partial pressure and the total pressure in a gas mixture
Term
"If you know the percentage of a specific gas, how can total pressure be calculated?"
Definition
"if you have an amount of 21% and you know atmospheric pressure, take .21 times atmospheric pressure and that gives the total pressure"
Term
What do high atmospheric pressures exert in the atmosphere
Definition
the PIO2
Term
What are pressures above atmospheric pressure called
Definition
hyperbaric pressure - underwater diving or hyperbaric chamber
Term
"66 feet under water, pressure is at 2280 mmhg so what is the oxygen in an air mixure breathed by a diver?"
Definition
PO2 of .21x2280 or approx 479 mm hg which is nearly three times the PO2 at sea level
Term
how are hyperbaric chambers used clinically
Definition
hyperbaric chambers are used together with oxygen to treat a variety of conditions including carbon monoxide poisoning and gangrene
Term
can gases dissolve in liquids
Definition
"yes, i.e. carbonated water and soda"
Term
what is Henry's Law
Definition
it predicts how much of a given gas will dissolve in a liquid. at a given temp the volume of a gas that dissolves in a liquid is equal to its solubility coefficient
Term
How does temperature affect gas solubility
Definition
high temp decreases solubility and low temp increases solubility which is why an open can of soda may still fizz if left in teh refrigerator but quickly goes flat when left at room temp
Term
what is temperature's effect on solubility a result of
Definition
changes in kinetic activity
Term
what happens to kinetic activity of any dissolved gas as a liquid is warmed
Definition
"it is increased and this increases the molecules' escaping tendency and partial pressure. as an increasing number of gas olecules escape, the amt left decreases rapidly"
Term
What are the three basic assumptions underlying all gas laws
Definition
"no energy is lost during molecular collisions, the volume of th eolecules themselves is negligible, no forces of mutual attractio exist between these molecules "
Term
what is the effect of water vapor on gas law calculations
Definition
water vapor takes up space therefore dry volume of a gas at a constant pressure and temp is always smaller than its saturated volume and the opposite is also true
Term
"The pressure exerted by water vapor is independent of other gases with which it mixes, depending only on the temp and RH therefore what?"
Definition
the addition of water vapor to a gas mixture always lowers the partial pressures of the other gases present
Term
what is the highest temperature that a substance can exist as a liquid called
Definition
critical temperature
Term
what is the pressure needed to maintain equilibrium between the liquid and gas phases of a substance
Definition
critical pressure
Term
"what together, represent the critical point of a substance"
Definition
the critical temperature and critical pressure
Term
What can be applied to distinguish between a true gas and a vapor
Definition
concept of critical pressure
Term
What concept helps explain how gases are liquified
Definition
the concept of critical temperature
Term
what are the two ways a gas can be liquified
Definition
by cooling it to below its boiling point or cooling it to its critical temperature and then being compressed
Term
Can a gas existing above its critical temperature ever be liquified by pressure alone?
Definition
no
Term
Can a gas with a critical temperature above ambient (as in room temperature) be liquified by pressure alone?
Definition
yes
Term
what gases can be stored at room temp in liquid form
Definition
CO2 and N20
Term
how is liquid oxygen stored
Definition
in insulated containers at temps below -183 C or 297F
Term
what is flow
Definition
the bulk movement of a substance through space
Term
what is the study of fluids in motion
Definition
hydrodynamics
Term
what does a static liquid's pressure depnd solely upon
Definition
the depth and density of the fluid
Term
what does the pressure exerted by a liquid in motion depend upon
Definition
the nature of the flow itself
Term
explain the pressure exerted by a static fluid on a liquid column
Definition
"it is dependent only upon height of the liquid column. when the fluid flows out through the bottom tube, the pressure progressively falls all along the tube length. the decrease in pressure between each of the equally spaced vertical tubes is the same."
Term
what does the second law in thermodynamics state
Definition
"in any mechanbical process, there will always be a decrease in the total energy available to do work"
Term
"with regard to fluid in a tube, where does frictional resistence to flow exist"
Definition
within the fluid itself (viscosity) and between the fluid and the tube wall
Term
"for any given tube length, flow reistance equals what"
Definition
the difference in pressure between the two points along the tube divided by the actual flow
Term
what are the three primary patterns of flow
Definition
"laminar, turbulent, transitional"
Term
"during laminar flow, how does a fluid move"
Definition
discrete cylindrical layers or streamlines
Term
"what is the difference pressure required to produce a given flow, under conditoins of laminar flow through a smooth tube of fixed size"
Definition
defined by Poiseuille's law
Term
"according to poisulle's law, for fluids flowing in a laminar pattern, what happens to the driving pressure whenever the fluid viscosity, tube length, or flow increases"
Definition
driving pressure will increase
Term
what happens when fluid molecules form irregular eddy currents in a chaotic pattern called what?
Definition
turbulent flow
Term
what does the chageover from laminar to turbulent flow entail?
Definition
dependent on several factors such as: fluid density (d) viscosity (h) linear velocity (v) and tube radius (r)
Term
"what do viscosity, linear velocity and tube radius determine?"
Definition
Reynold's number
Term
"in a smooth-bore tube, when does laminar flow become turbulent"
Definition
when Nr exceeds 2000 (the number is dimensionless)
Term
what are conditions that favor turbulent flow
Definition
"increased fluid velocity, increased fluid density, increased tube radius, or decreased fluid fiscosity"
Term
what law no longer applies when flow becomes turbulent
Definition
Poiseuille's law.
Term
what is the relationship between driving pressure and flow when flow is laminar (Poiseulle's law)
Definition
the relationship is linear
Term
"when flow becomes turbulent, driving pressure varies with the square of the flow. how is flow doubled under laminar conditions?"
Definition
double the driving pressure
Term
how is flow doubled under turbulent conditions
Definition
the driving pressure would need to be indreased four-fold
Term
what is transitional flow the mixture of
Definition
laminar and turbulent flow
Term
"when flow is mainly laminar, how is the pressure varied"
Definition
linearly with the flow
Term
"when flow is mainly turbulent, how does driving pressure vary"
Definition
exponentially with the flow
Term
what is the contrast of flow vs velocity
Definition
flow is bulk movement of a volume of luid per unti of time (L/min or L/sec) vs. velocity as a measure of linear distance traveled by the fluid per unit of time (cm/sec)
Term
what is the key factor relating velocity to flow
Definition
cross-sectional area of the conducting system
Term
what is the law of continuity
Definition
velocity of a fluid moving through a tube at a constant flow varies inversely with the available cross-sectional area
Term
What is the bernouli effect
Definition
"when a fluid flows through a tube of uniform diameter, pressure decreases progressively over the tube length however when fluid passes through a constriction, pressure drop is greater. total energy at a given point in a fluid stream must be the same throughout the tube. because a moving fluids velocity and lateral pressure sum must always be equal, they must vary inversely with each other"
Term
what happens when a flowing fluid encounters a very narrow passage
Definition
its velocity can increase greatly
Term
what happens when a flowing fluid encounters a very narrow passage that causes a rise in velocity that is so great that the fluid's lateral pressure falls below that of the atmosphere
Definition
"if an open tube is placed distal to such a constriction, this negative pressure can actually pull another fluid into the primary flow stream and is called fluid entrainment"
Term
what is a venturi tube
Definition
"a modified entrainment device developed by giovanni ventura and it widens just after its jet or nozzle and as long as the angle of dilation is less than 15 degrees, this widening helps restore fluid pressure back toward prejet levels"
Term
what is the major drawback of a venturi tube
Definition
any buildup of pressure downstream from the entrainment port decreases fluid entrainment
Term
how does a pitot tube overcome the drawback of a venture tube
Definition
"rather than restoring fluid pressure, a pitot tube restores fluid velocity which lessens the effect of downstream pressure on fluid entrainment"
Term
what is fluidics
Definition
"the branch of engineering that appies hydrodynamic principles in flow circuits for purposes such as switching, pressure and flow sensing and amplification"
Term
what is the coanda effect and what device uses this effect
Definition
used in most fluidic circuitry. when fluid flows through a small orifice with property contoured downstream surfaces a phenomenon called wall attachment occurs
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