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mech-eng
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I would like to ask you that why pressure drop is constant through pipe? How can we know that dP/dx=constant?
Thank you.
Chestermiller said:If it's an incompressible fluid, how does the fluid know that the conditions in one part of the pipe are different from another part of the pipe?
Chestermiller said:The average fluid velocity is the same everywhere.
Chestermiller said:If the fluid velocity is constant throughout the pipe, then everything else about the flow must also be constant, including the axial pressure gradient. What other possibility is there?
boneh3ad said:What is your existing background in fluid mechanics? Have you ever taken a course in the subject?
Try reading the first few chapters of Transport Phenomena by Bird, Stewart, and Lightfoot.mech-eng said:I do not know what other possibility is but I want to study it. Under what topics of fluid mechanics, can I find this situation. And would you like to explain with what equation or from where do we know that if fluid velocity is constant then all other things should be constant. This means that all other things only the function of velocity as well.
So, I will study more but I need guidance.
Thank you.
What if the substance is a gas (axially varying velocity) or if the temperature is varying axially (axially varying viscosity). The the pressure gradient is not constant for these situations. Do you still maintain that this is the definition of the the pressure loss?Rx7man said:The equation posted is the definition of pressure loss over the length at a given velocity.. (Initial pressure-final pressure)/length...
I agree. But it's certainly not a definition.Rx7man said:I'd say so... the formula given doesn't account for any variation of other parameters...
If you wanted a formula to include different flow rates, viscosities, pressures, compressability, etc it would get complicated really quickly..
As presented, at a given pressure, flow, and viscosity, you can find the pressure drop per unit length.
Chestermiller said:If it's an incompressible fluid, how does the fluid know that the conditions in one part of the pipe are different from another part of the pipe? The average fluid velocity is the same everywhere.
Pressure drop is the decrease in pressure that occurs as fluid flows through a pipe. This can be caused by factors such as friction between the fluid and the pipe walls, changes in elevation, and obstructions in the pipe.
The pressure drop in a pipe can be calculated using the Darcy-Weisbach equation, which takes into account factors such as pipe diameter, fluid velocity, and pipe roughness. Other methods, such as the Hazen-Williams equation, may also be used depending on the specific situation.
Head loss is the decrease in energy or pressure that occurs as fluid flows through a pipe. It is often used interchangeably with pressure drop, but technically refers to the energy loss rather than the decrease in pressure.
Head loss in pipe flow can be caused by various factors, including friction between the fluid and pipe walls, changes in elevation, and obstructions in the pipe. These factors contribute to the overall energy loss of the fluid as it moves through the pipe.
Head loss can be reduced by increasing the pipe diameter, smoothing out the interior surface of the pipe, reducing the fluid velocity, and minimizing obstructions in the pipe. These measures can help to decrease the friction and energy loss in the pipe flow system.