What is the role of $$\hat{\jmath} \times r$$ in computing vorticity?

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Discussion Overview

The discussion revolves around the term $$\hat{\jmath} \times r$$ in the context of fluid motion and its role in computing vorticity. Participants seek clarification on the meaning and implications of this term within the framework of fluid dynamics.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant presents a fluid motion equation involving $$\hat{\jmath} \times r$$ and expresses the need to understand this term to find vorticity.
  • Another participant asks for clarification on the context of $$\hat{\jmath} \times r$$ and requests the full question to provide better assistance.
  • A later reply identifies $$\hat{\jmath} \times r$$ as the cross product of the unit vector $$\hat{\jmath}$$ and the vector $$r$$, questioning whether the inquiry pertains to its computation or its physical meaning.
  • It is noted that $$r$$ is the positional vector of the volume element relevant to the velocity calculation.

Areas of Agreement / Disagreement

Participants express varying levels of understanding regarding the term $$\hat{\jmath} \times r$$, and there is no consensus on its specific implications or how to compute it.

Contextual Notes

There are unresolved aspects regarding the definitions of $$r$$ and the specific physical context in which $$\hat{\jmath} \times r$$ is applied, which may affect interpretations.

shen07
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A fluid motion has velocity $$\underline{u}=\sin{(at)}\hat{\imath}+\hat{\jmath} \times r +\cos{(at)}\hat{k}$$

I need to know what is $$\hat{\jmath} \times r$$ to find Vorticity and other things.
 
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shen07 said:
Hi guys, i am solving a problem but I am unable to figure out what is $$\hat{\jmath} \times r$$? Please help me


Hi shen07, :)

Obviously what is meant by $\hat{\jmath} \times r$ depends on the context. Can you post the full question please?
 
Sudharaka said:
Hi shen07, :)

Obviously what is meant by $\hat{\jmath} \times r$ depends on the context. Can you post the full question please?

I just edited it
 
shen07 said:
I just edited it

I edited the thread title. Please do not use $\LaTeX$ in thread titles. I have also moved this thread.
 
shen07 said:
A fluid motion has velocity $$\underline{u}=\sin{(at)}\hat{\imath}+\hat{\jmath} \times r +\cos{(at)}\hat{k}$$

I need to know what is $$\hat{\jmath} \times r$$ to find Vorticity and other things.
$\hat{\jmath} \times r$ is the cross product of $\hat{\jmath}$ and $r$, but you already know this. Are you asking how to compute it? Then see here. Are you asking what $\hat{\jmath}$ and $r$ are? It looks like $\hat{\imath}$, $\hat{\jmath}$ and $\hat{k}$ are unit coordinate vectors. I don't know what $r$ is. Or are you asking what the physical meaning of the term $\hat{\jmath} \times r$ is?
 
$r$ would be the positional vector of the volume element for which we're calculating the velocity.
 

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