CVS 4 Flashcards
What does the Bernoulli principle state?
Bernoulli’s Equation states that the work done on a fluid as it moves from one place to another is equal to the change in its mechanical energy.
∆𝑊= ∆𝑃𝐸+ ∆𝐾𝐸
(work energy relation)
When a liquid flowing through a pipe of two regions of different diameters, the velocity of the liquid will ____.
change.
The change in velocity involves an acceleration, a, which means there is a…
net force acting upon the liquid (F = ma).
𝑃+1/2 𝜌𝑣^2+𝜌𝑔ℎ=𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡
What does each represent?
Where P is the external pressure, 1/2 𝜌𝑣^2 is the kinetic energy and 𝜌𝑔ℎ is the fluid pressure (potential energy).
Bernoulli’s Equation can only be used given the following assumptions:
- Fluid is incompressible (i.e. its density does not change).
- Fluid is non-viscous (i.e. no appreciable frictional effects).
- Fluid flow is streamline
. - Flow velocity at a fixed point does not change rapidly (i.e. steady state conditions apply).
i.e. Bernoulli’s Equation is only an approximation
If Velocity Increases –>
If Velocity Decreases –>
Pressure Decreases
Pressure Increases
P + 𝜌gh is the _______ term.
pressure
½ 𝜌v2 is the ______ term.
velocity
An aneurysm is a
swelling in a blood vessel which may rupture – can be fatal.
Aneurysms usually occur due to a…
weakness in the wall of the vessel which ‘bubbles’ due to the fluid pressure within the vessel.
Once an aneurysm starts, it will continue to grow until:
- It cannot grow anymore because of an obstruction (bone or tissue obstruction or stent),
- The elastic tension in the vessel wall is large enough to contain it,
- It bursts.
The fact that the aneurysm continues to grow is a direct consequence of the Continuity Principle and the Bernoulli Principle, why?
- Since the fluid pressure acts perpendicular to the surface, it will cause the vessel wall to swell in the region of weakness
- As the cross-sectional area gets bigger, the velocity decreases (Continuity Equation).
As the velocity decreases, the fluid pressure increases (Bernoulli Principle).
Detected aneurysms may be treated by clamping the blood vessel or using a…
stent.
A stent is a…
cylindrical ‘tube’ which can be placed within the lumen of the blood vessel at the location of the aneurysm.
A stent will contain the blood (allowing it to flow through it), but stop…
the fluid pressure from acting directly on the vessel wall where the aneurism exists.