Uniform & Non Uniform Flow Types

[MatthewMansfield]

Hello all

I am trying to understand the difference between different types of fluid flow specifically Uniform and Non Uniform flow.

My understanding is that uniform flow can be defined as "fluid flow in which the fluid characteristics such as velocity, pressure, density at a point or area (depending on your control volume) does not change with respect to the cross section / area / length."

My understanding of non uniform flow is "fluid flow in which the fluid characteristics such as velocity, pressure, density at a point or area (depending on your control volume) changes with respect to the cross section / area / length."

With this definition in mind if i had a pipe with a constant cross section with fluid flowing through it then if the fluids properties such as velocity, pressure density etc did NOT change as the fluid traveled through the pipe then the fluids flow can be defined as uniform.

Similarly if I had a pipe where the cross section varied along the pipe then as the fluid flowed through the pipe its properties such as velocity, pressure density etc did change then the fluids flow can be defined as non uniform.

If this is correct then what if i had a situation where i had a constant cross section pipe and fluid traveled through it and the fluids properties such as density, velocity, pressure etc did change then would this is defined as uniform or non uniform flow?

You thoughts?

Thank you.

 

[TrussBridgeboy]

Based on your own definitions, then you've answered your own question - non-uniform. Is your pipe "full" or an open channel type flow as in a drain pipe? It's been a long time since I've broached the subject but hydraulic jump comes to mind of your situation if it's open channel type flow.

 

[1503-44]

Uniform flow is when there is no depth change. What you said, but not with respect to channel width or cross-section. It is with respect to channel slope. Uniform flow in an open channel occurs at the one particular slope where flowing friction loss equals the gravitaional energy gained by the decrease in elevation. If the slope is too steep, flow in the channel will accelerate as it moves downhill ... and depth will decrease. If the slope is too shallow, the flow will decellarate ... and depth will increase.

“What I told you was true ... from a certain point of view.” - Obi-Wan Kenobi, "Return of the Jedi"