# Would greater flow take precedence over velocity in pressure

• hongiddong
In summary, there are two equations that determine pressure in a pipe: the Bernoulli equation, which applies to "inviscid" flow with no resistance, and the equation for pressure, which assumes a viscous flow with a constriction. In the case of an artery, it is considered upstream of a viscous restriction, making the equation for pressure more relevant in determining pressure on the arterial walls.
hongiddong
The equation for mean arterial pressure = flow * resistance, however, if we increase flow we would increase velocity by the equation Velocity = flow/ cross sectional area, and velocity would decrease pressure according to bernoullies law?

Which would take precedence in generating more pressure on the arterial walls?

hongiddong said:
The equation for mean arterial pressure = flow * resistance, however, if we increase flow we would increase velocity by the equation Velocity = flow/ cross sectional area, and velocity would decrease pressure according to bernoullies law?

Which would take precedence in generating more pressure on the arterial walls?
Bernoulli is for "inviscid" flow -- no resistance. You have a pipe with approximately the same pressure at inlet and outlet and find that the pressure varies depending on the flow velocity. Center of the constrictions = low pressure. Wide points = ambient pressure.

An equation for pressure = flow * resistance assumes the opposite. A viscous flow. You have a pipe with a constriction. Upstream of the constriction you have a high pressure, downstream you have low pressure. The pressure drop scales with flow and with resistance. Upstream of constriction = high pressure, downstream = low pressure.

An artery is pretty much by definition "upstream" of a viscous restriction (the capillaries).

[Caveat: I have zero real world experience with medicine, blood pressure and fluid dynamics]

hongiddong

## 1. What is flow and velocity in relation to pressure?

Flow refers to the volume of fluid passing through a given area in a specific amount of time, while velocity is the speed at which the fluid is moving. In terms of pressure, flow and velocity are both important factors that can affect the pressure of a fluid.

## 2. Why is greater flow important in regards to pressure?

Greater flow means that more fluid is passing through a given area, which can lead to an increase in pressure. This is because the force of the fluid against the walls of the container or pipe increases as more fluid is present, resulting in a higher pressure.

## 3. How does velocity affect pressure?

Velocity also plays a significant role in determining pressure. As the velocity of a fluid increases, the pressure of the fluid decreases. This is due to the Bernoulli's principle, which states that as the velocity of a fluid increases, its pressure decreases.

## 4. Which of the two, flow or velocity, has a greater impact on pressure?

It depends on the specific situation. In some cases, a higher flow rate may result in a higher pressure, while in others, a higher velocity may cause a decrease in pressure. Both flow and velocity should be considered when analyzing the pressure of a fluid system.

## 5. How can flow and velocity be manipulated to control pressure?

Flow and velocity can be manipulated by altering the size of the container or pipe, changing the fluid's properties (such as density or viscosity), or adjusting the amount of fluid being introduced into the system. By controlling flow and velocity, the pressure of a fluid can be controlled as well.

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