Turbulence Kinetic Energy in pipe flow

In summary, the equation used to estimate the turbulence kinetic energy per unit volume in pipe flow is 0.5*(U^2), where U is the average velocity in the pipe. This equation can also be used to solve for the velocity if the head loss and friction factor are known. There are also other equations and models, such as the k-ε model, that use turbulent kinetic energy to represent the turbulent properties in CFD simulations. However, for everyday use in practical pipes, the flow is primarily turbulent and the kinetic energy can be approximated using the 0.5*(U^2) equation.
  • #1
Richardf
2
0
What is the equation to estimate the turbulence kinetic energy per unit volume in pipe flow? Any information is appreciated.

Thanks.
 
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  • #3
In most practical pipes for everyday use, the flow is primarily turbulent. The kinetic energy would just be 1/2 m*v^2, where m is the mass of a section of fluid in the pipe and v is the velocity of that fluid where you picked it.

You could solve backwards for the velocity if you knew the head loss and friction factor in the pipe (can get off a Moody chart using pipe surface roughness and the turbulence of the flow).
http://en.wikipedia.org/wiki/Darcy_friction_factor

http://en.wikipedia.org/wiki/Moody_chart
 
  • #4
Turbulent kinetic energy is particularly useful when looking at CFD turbulence models. For example, the very standard k-ε model uses turbulent kinetic energy as one of the "transported" variables representing the turbulent properties.
 
  • #5
Thanks for your replies.

I agree that the MEAN kinetic engergy per unit mass can be approximated as,

0.5*(U^2) where U is the average velocity in pipe.

Is there a similar equation that can be used to estimate the Turbulence kinetic energy per unit mass in pipe flow? such as

0.5*f(U'^2) wehre f is the friction factor

Or some other equations?
 

Related to Turbulence Kinetic Energy in pipe flow

1. What is turbulence kinetic energy in pipe flow?

Turbulence kinetic energy in pipe flow is the measure of the energy associated with the chaotic, random motion of fluid particles within a pipe. It is a key parameter in understanding the behavior of fluids in pipes and is an important factor in determining the efficiency of fluid transport and mixing processes.

2. How is turbulence kinetic energy calculated?

Turbulence kinetic energy is typically calculated using the Reynolds stress tensor, which is a mathematical representation of the turbulent fluctuations in fluid flow. This tensor is then used to calculate the variance of the fluid velocity, which is then converted to turbulence kinetic energy.

3. What factors affect turbulence kinetic energy in pipe flow?

There are several factors that can affect turbulence kinetic energy in pipe flow, including the velocity of the fluid, the diameter of the pipe, the viscosity of the fluid, and the roughness of the pipe surface. Additionally, any changes in the flow rate or flow direction can also impact turbulence kinetic energy.

4. How does turbulence kinetic energy impact fluid flow in pipes?

Turbulence kinetic energy can have a significant impact on fluid flow in pipes. It can lead to increased mixing and transport of particles, as well as increased friction and energy losses. In some cases, turbulence kinetic energy can also cause damage to pipes and equipment due to the high intensity of the fluid motion.

5. Can turbulence kinetic energy be controlled or reduced in pipe flow?

Yes, turbulence kinetic energy can be controlled or reduced in pipe flow through various methods such as increasing the pipe diameter, decreasing the roughness of the pipe surface, or using flow control devices. Additionally, controlling the flow rate and direction can also help to reduce turbulence kinetic energy in pipe flow.

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