Bernoulli principle or due to Viscosity?

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Discussion Overview

The discussion centers around the reasons for the variation in water speed within a smooth flowing stream, specifically questioning whether this phenomenon is due to adhesion, cohesion, viscosity, or the Bernoulli principle. The scope includes theoretical considerations and conceptual clarifications related to fluid dynamics.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions the relevance of the Bernoulli principle in explaining the speed variation, asking for a definition of a streamline.
  • Another participant asserts that viscosity is the primary factor, suggesting a need to understand the concept of a boundary layer.
  • A different viewpoint applies Bernoulli's principle, arguing that higher pressure at the sides due to adhesion and cohesion results in lower velocity, while lower pressure in the middle allows for higher velocity.
  • Another participant supports the viscosity argument, explaining that viscosity leads to a no-slip condition at the walls, resulting in zero velocity at the wall and a faster flow in the middle.

Areas of Agreement / Disagreement

Participants express differing views on the primary cause of the speed variation, with some advocating for viscosity and others for the Bernoulli principle. The discussion remains unresolved with multiple competing perspectives.

Contextual Notes

Participants reference concepts such as adhesion, cohesion, viscosity, and the Bernoulli principle without reaching a consensus on their applicability or interrelation in this context.

abrowaqas
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Why the speed of water in the middle of the smooth flowing stream is high than its speed on the sides?

Is it due to Adhesion or cohesion forces or viscosity or Bernoulli principle holds here?
Kindly tell me exact reason .
 
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What is your precise reasoning for thinking Bernoulli might be relevant here?
In particular:
What is a streamline?
 
It is due to viscosity. You should look read about a boundary layer.
 
But if we apply bernoulli's principle here: I-e
" where the pressure is high in a fluid there is low velocity and where the pressure is low in a fluid motion , velocity will be higher..
We know that at sides there is more pressure due to Adhesion and Cohesion forces hence speed is low.
However at middle only cohesion forces are available that low pressure hence more velocity ..
 
Like RandomGuy88 said, all you have to think about is viscosity. Viscosity enforces the no-slip condition, i.e. the velocity at the wall relative to the wall is zero, hence you have zero velocity at the wall. In the middle it is obviously faster than zero.
 

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