4.3 - Fluid Dynamics

Question 1

Viscosity and fluid behavior

Answer 1

• a measure of internal resistance to flow
• high viscosity creates high viscous drag
• low viscosity fluids behave like ideal fluids, which are inviscid

Question 2

Laminar flow and associated flow rate

Answer 2

• laminar flow is smooth, orderly and oft modeled as parallel lines that do not necessarily have equal velocity
• for laminar flow, rate of flow through a confined space can be calculated with Poiseuille’s law

Q=(PIr^4DeltaP)/(8etaL)

Question 3

Turbulent flow and critical speed

Answer 3

• rough, characterized by eddies (typically downstream of disruption)
• may arise in unobstructed flow if certain critical speed is exceeded (may be calculated with a standard equation which involves the Reynolds # constant). Here, laminar flow occurs only in boundary layer adjacent to barrier

Question 4

Continuity equation

Answer 4

-assumes a constant flow rate
Q=V1A1=V2A2
-cardiac system is a closed loop with a non constant flow rate

Question 5

Bernoulli’s equation

Answer 5

• sum of static, dynamic pressure will be constant in closed system for incompressible fluid not experiencing viscous drag
• describes relationship between pressure and linear speed (and height, if elevation change occurs)

Question 6

Pitot tubes

Answer 6

Measurement devices that determine speed of a fluid by taking difference in static and dynamic pressure at different points

Question 7

Venturi effect

Answer 7

-demonstrates direct relationship between cross sectional area and pressure: results from combination of continuity and Bernoulli equations

Question 8

Fluid dynamics

Answer 8

Study of actively flowing fluids

Question 9

Inspiration and expiration

Answer 9

Create a pressure gradient that influences the respiratory system and the venous portion of the circulatory system