Lesson 20 (Part 1) Flashcards
What are 2 types of flow?
- Laminar
- Turbulent
- non laminar
What are 3 types of laminar flow?
- Plug flow
- Parabolic
- Disturbed flow
Where is plug flow?
At the entrance to tubes
How does blood move in plug flow?
As a unit
What is the speed in plug flow?
The same speed across the vessel
Where is parabolic flow?
After entering the straight tube
What is an example of parabolic flow?
Common carotid artery
Where is the speed the fastest in parabolic flow?
In the center of the tube
Where is the speed the slowest in parabolic flow?
At the tube walls
What is the average flow speed in the parabolic flow?
1/2 the fastest speed
Laminar
Layers
When do you get disturbed flow? (2)
- At a stenosis
2. At bifurcation
What is disturbed flow still considered?
Laminar flow, but the streamlines are not straight
- non-parabolic
When does turbulent flow occur?
Usually after a significant stenosis
Turbulent flow
Chaotic, multidirectional, multispeed flow
- non-laminar
What does turbulent flow have?
Eddies
Eddies
Flowing circles
What is the overall flow in turbulent?
Forwards
What kind of noise could you hear with turbulent flow?
Bruit
- main reason to get an ultrasound
What does turbulent flow depend on?
Reynolds number
What is the critical reynolds number for blood?
2000
What can be produce with critical reynolds?
Turbulent flow
- flow must surpass a critical Reynolds number to cause turbulent flow
What is the formula for Reynolds number?
Re = pvd/n Re = renolds number p = density of fluid v = velocity of fluid d - diameter of pipe n = viscosity
What happens to Re if velocity goes up?
It increases
What happens to Re if the diameter of the vessel increases?
It increases
What happens to Re if viscosity goes up?
It decreases
Re
Reynolds number = turbulence
Stenosis
Partial blockage
Occlusion
Complete blockage
