Finding out Shear rate of a bent pipe which has different bend radius values

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Discussion Overview

The discussion centers on calculating the shear rate in a bent pipe with varying bend radii, specifically addressing the complexities introduced by the geometry of the pipe and the flow characteristics. Participants explore theoretical approaches and practical considerations related to fluid dynamics in curved pipes.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant presents a formula for shear rate in simple pipes and questions how to adapt it for a bent pipe with different radii.
  • Another participant expresses skepticism about deriving the geometry of the system from the initial description.
  • A participant notes that the shear rate at the wall varies around the circumference in curved sections, suggesting that a single value cannot be assigned to the flow.
  • It is proposed that if the radius of curvature is large compared to the pipe diameter, the shear rate can be approximated as if the pipe were straight.
  • One participant mentions specific dimensions (50 mm radius of curvature and 40 mm diameter) and inquires about a ratio to determine if the shear rate can be considered negligible.
  • Another participant suggests a ratio of 10:1 for evaluating the significance of the shear rate in this context.
  • Some participants express difficulty in finding established calculations for bent pipes and question whether experimentation is the only viable method.
  • It is suggested that research on laminar flow in curved pipes or toroidal flow may provide relevant insights.

Areas of Agreement / Disagreement

Participants express differing views on the feasibility of calculating shear rates in bent pipes, with some proposing approximations while others highlight the complexities involved. The discussion remains unresolved regarding the best approach to take.

Contextual Notes

Limitations include the lack of consensus on the applicability of various ratios and the absence of established formulas specifically for bent pipes. The discussion also reflects uncertainty about the adequacy of theoretical models versus experimental methods.

Baybora
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which has different radiuses at both end. Its actually two pipes merging after the entrance going straight and somewhere close to middle of the pipe it's bent 90°.

So for simple pipes it's
=4*Q
π*r^3

But what for the pipe I mentioned? Is there any way to solve that or at least minimize the error?
 
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Do you really think we can figure out the geometry of the system from your description?
 
bent pıpe.png


here is the shape I was talking about. Hope this helps
 
bump
 
Baybora said:
View attachment 97168

here is the shape I was talking about. Hope this helps
The shear rate at the wall varies with position around the circumference for the curved sections, so there is no one value of the shear rate that you can assign to the flow. However, if the radius of curvature of the bends is large compared to diameter of the pipe, a good approximation is to use the shear rate as if the pipe were not curved.
 
Chestermiller said:
The shear rate at the wall varies with position around the circumference for the curved sections, so there is no one value of the shear rate that you can assign to the flow. However, if the radius of curvature of the bends is large compared to diameter of the pipe, a good approximation is to use the shear rate as if the pipe were not curved.
It looks like the curve Radius is 50 mm and the pipe diameter before the curve is 40 mm. Is there any specific ratio to determine if the result of fixed shear rate could be negligible?
 
Baybora said:
It looks like the curve Radius is 50 mm and the pipe diameter before the curve is 40 mm. Is there any specific ratio to determine if the result of fixed shear rate could be negligible?
I would go by 10:1
 
I couldn't find anything regarding to calculation of a bent pipe. Is there even a way other than experimenting?
 
Baybora said:
I couldn't find anything regarding to calculation of a bent pipe. Is there even a way other than experimenting?
You should be able to find Laminar Flow in curved Pipe or Toroidal flow
 

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