Concept of Pressure head and velocity head

In summary: That is Pressure, Velocity, Elevation, and Area. So Pressure Head is the summation of all those terms. Velocity Head is the summation of Pressure and Elevation. Area Head is the summation of both Velocity and Elevation. And finally, Kinetic Energy is the summation of Pressure, Velocity, and Elevation.
  • #1
shiv_99
6
0
I am rather confused regarding the exact definitions of pressure head and velocity head. wikipedia defines pressure head as "a term used in fluid mechanics to represent the internal energy of a fluid due to the pressure exerted on its container. " But how can pressure head represent energy since it has dimension M°L[itex]^{1}[/itex]T°. Please clear my concept.
 
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  • #2
shiv_99 said:
I am rather confused regarding the exact definitions of pressure head and velocity head. wikipedia defines pressure head as "a term used in fluid mechanics to represent the internal energy of a fluid due to the pressure exerted on its container. " But how can pressure head represent energy since it has dimension M°L[itex]^{1}[/itex]T°. Please clear my concept.

This wikipedia definition is awful. Pressure is force per unit area, and the term "head" usually refers to how high a given pressure can raise a static column of liquid (typically water). I think of internal energy as a thermodynamic concept, and, although pressure affects the internal energy of a material, it is not its internal energy. Pressure has units of energy per unit volume, so some people think of it as an energy concept, but this conceptualization has never worked for me. Velocity head relates to the stagnation pressure of a liquid or gas. Basically, how high a column of water the stagnation pressure could support.
 
  • #3
Bernoulli's equation is an energy conservation equation, with relations of a specific point along a streamline:
Velocity --> kinetic energy
elevation --> potential energy
pressure --> internal energy

one way to look at it is from PV=nRT
or P = nRT/V
since internal energy U is a function of T ...

also
P = F/A = (F d ) / (A d ) = W / V = energy / volume

Most people when manipulating Bernoulli, think of the parts of the equation in the same way Chestemiller describes, at least I do.
 

Related to Concept of Pressure head and velocity head

1. What is the concept of pressure head?

The concept of pressure head is a measure of the potential energy of a fluid due to its pressure. It is defined as the vertical distance between a point in a fluid and a reference point where the pressure is zero.

2. How is pressure head related to pressure?

Pressure head is directly proportional to pressure, meaning that as pressure increases, so does pressure head. This is because the higher the pressure, the greater the potential energy of the fluid.

3. What is the significance of pressure head in fluid mechanics?

Pressure head is an important concept in fluid mechanics as it helps us understand and analyze the behavior of fluids in various systems. It is used to calculate the total energy of a fluid and is crucial in determining the flow rate and velocity of a fluid in a pipe or channel.

4. What is velocity head?

Velocity head is a measure of the kinetic energy of a fluid due to its velocity. It is defined as the vertical distance between a point in a fluid and a reference point where the velocity is zero.

5. How is velocity head related to velocity?

Similar to pressure head, velocity head is directly proportional to velocity. This means that as the velocity of the fluid increases, so does the velocity head. This relationship is important in understanding the energy balance of a fluid and its behavior in different systems.

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