FLUIDS and FLOW-CH5 Flashcards
Fluids is a term used to describe
Liquid or gas
Important characteristic of fluids and gases
Flow
Hydrostatic
study fluids are not moving
Hydrodynamics
fluids in motion
Both hydrostatic and hydrodynamics involve
pressure and density
Pressure in a liquid is calculated using
density and height of the fluid
P in a liquid formula:
dhg (pressure = density * height*gravity )
To include pressure exerting force on the liquid’s surface, simply add it to equation
P2 is the ________ and P1 is the
P2 = P1 + dhg
pressure in the liquid; pressure of the gas added.
Calculate the pressure of a depth of 1000m below the surface on the ocean. Density is 1.03x10^3. 1 atm = 101325
P2 =P1 +dhg
P2= 1.07 x10^7
Definition of flow
Quantity of fluid passing a point per unit of time
Flow (definition formula)
V / t
Pressure =
relating to flow
F x R
P= pressure
F= Flow
R= Resistance
Change in flow written as
Q= QDot
2 types of flow
Laminar flow
Turbulent flow
Laminar flow most important factor : Remember mnemonic:
VISCOSITY
LVS
Laminar flow reynolds number:
<2000
Turbulent Flow Reynolds number
Reynolds >3000
Turbulent flow most important factor
Density
Molecules close in the center moving faster in (because of drag)
Laminar
Turbulent flow has a
continuous varying pattern of flow , chaotic and abruptly changing.
Best way to measure flow
POUISELLE”S LAW
What POUISELLE”S LAW
Flow = P /R
Turbulent flow occurs at _____velocity
High
Bigger factor for turbulent flow
density
Viscosity represented by and is defined as __________
n; Viscosity is the resistance a fluid offers to the motion of a solid through it
POUISEILLE’s LAW (KNOW THIS )
F = Pir^4 change P/ 8 nl
Resistance to flow
R = 8nl/Pi r^4
Pouiseille’s Law
F flow in L/s n= viscosity in Pa/s P= Pressure in pascals r= radius l= length
Double length
Flow in half
Biggest factors that affect vessel
Radius of vessel
Radius increase by
area changes power of 4
Volume increases by power of 8
Calculate aortic blood flow
Blood viscosity = 0.0015Pas. Pressure of 13000pa, is applied r=0.0010 ; l= 1.0
F= 3.4 x 10 ^-2 m^3/s