Quick questions about Area-Velocity relation

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Discussion Overview

The discussion revolves around the validity of the area-velocity relation in fluid dynamics, particularly in the context of real gases and specific duct shapes. Participants explore its applicability to compressible versus incompressible flows and the implications of using this relation in practical scenarios.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant questions the validity of the area-velocity relation for real gases, suggesting that its derivation relies on isentropic flow assumptions.
  • Another participant asserts that the area-velocity relation can only be applied to incompressible flow, where density remains constant, referencing the continuity equation.
  • A different participant presents a specific formulation of the area-velocity relation, indicating a mathematical expression involving Mach number.
  • A follow-up inquiry seeks clarification on the meaning of Mach number and the applicability of the area-velocity relation to different types of gases, emphasizing that the continuity equation is not applicable to gases as they are compressible fluids.
  • One participant identifies Mach number as a key variable and expresses skepticism about the accuracy of results derived from the area-velocity relation for experimental purposes, while still acknowledging its usefulness.

Areas of Agreement / Disagreement

Participants exhibit disagreement regarding the applicability of the area-velocity relation to real gases and compressible flows, with no consensus reached on its validity in these contexts.

Contextual Notes

There are limitations regarding the assumptions made about flow conditions, particularly the distinction between compressible and incompressible fluids, which remain unresolved in the discussion.

Who May Find This Useful

This discussion may be of interest to students and professionals in fluid dynamics, particularly those exploring the behavior of gases in various flow conditions and the mathematical relationships governing fluid motion.

piano_girl
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Is it valid for real gases? My initial thought would be no, since the derivation is based on the assumption that the flow is isentropic.

Is it valid for square ducts?
 
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area velocity relation?

the continuity equation?

It can only be applied to incompressible flow, the density must remain constant.
 
No, the area velocity relation is dA/A = (M^2 -1) dV/V
 
hi piano girl-
what is the M?-can u tell us about this equation more clear?,and please tell us which kind of gases this equation can be applied?-continuity equation can't be applied for the gases-its only as Mr:mybsaccownt said-for incompressible flow-and the gases is an compressible fluids-in which the density not constant.
waiting you to tell us about this equation-it might be important,thanks .
 
Last edited:

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