Fluid dynamics - mass flow rate -dimensionless number

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Discussion Overview

The discussion revolves around the relationship between mass flow rate, friction losses in piping, and the applicability of dimensionless numbers, particularly Euler's number, in fluid dynamics. Participants explore theoretical implications and seek clarification on the concepts involved.

Discussion Character

  • Exploratory
  • Technical explanation
  • Homework-related

Main Points Raised

  • Some participants question whether low mass flow rates, such as 2g/s, result in negligible friction and other losses in piping.
  • There is a proposal that if losses are negligible, Euler's dimensionless number might be relevant to demonstrate this, but the connection is not clearly established.
  • One participant requests a proof involving Euler's number, while others inquire about alternative dimensionless numbers that could apply.
  • Another point raised is whether the main driving force at low mass flow rates is the vapor pressure of the gas.
  • Some participants encourage attempts to non-dimensionalize governing equations to identify driving terms and constants.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the applicability of Euler's number or the nature of losses at low mass flow rates. Multiple competing views and uncertainties remain regarding the theoretical framework and specific calculations.

Contextual Notes

Limitations include the lack of specific assumptions regarding flow conditions, the dependence on definitions of dimensionless numbers, and unresolved steps in the non-dimensionalization process.

Who May Find This Useful

This discussion may be useful for students and professionals interested in fluid dynamics, particularly those exploring mass flow rates and the implications of dimensionless analysis in practical applications.

JB Mandengue
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(a) Is it true that if the mass flow rate of a gas is low, say 2g/s (grams per second), the friction losses and other losses in the piping will be negligible?

(b) If it is true that losses in the piping are negligible, is it the Euler's dimensionless number that we can use to prove this?

(c) If it is the Euler's dimensionless number, please indicate the proof. If it is not Euler, which one is it?

(d) Is it true that at such low mass flow rates, the main driving force is the vapour pressure of the gas?
 
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If this is homework, please move it to the homework forum.

Thanks
Matt
 
At least throw an attempt and we'd be more likely to help you. Have you non-dimensionalized the governing equations? What terms do you see as constants?
 
minger said:
At least throw an attempt and we'd be more likely to help you. Have you non-dimensionalized the governing equations? What terms do you see as constants?

I haven't tried anything. I am looking for leads to point me in the right direction. The information I put about Euler is what I think it might be conceptually. But actually working it out I haven't tried.
 
Well as I mentioned, non-dimensionalize the equations, using standard non-dimensional terms and you immediately see what terms are driving. What terms can be driving if certain conditions are met.
 

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