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dRic2
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According to the book "transport phenomena" by Lightfoot, Byron and Stewart if you take the cross product of the equation of motion (for very small element of fluid) and the position vector ##r## you get the equation of change of angular momentum. After some manipulation of vectors and tensors the equation can be written in such a way that a this term shows up:
$$ -[ \mathbf \epsilon \mathbf : \mathbf \tau ] $$
Where ## \mathbf \epsilon ## is a third-order tensor and ## \mathbf \tau ## is the stress-tensor.
Then the authors say:
What "bulk angular momentum" is? I don't understand, why there are two angular momentum?
$$ -[ \mathbf \epsilon \mathbf : \mathbf \tau ] $$
Where ## \mathbf \epsilon ## is a third-order tensor and ## \mathbf \tau ## is the stress-tensor.
Then the authors say:
If, on the other hand, ## \mathbf \tau## is asymmetric, then the last term describes the rate of conversion of bulk angular momentum to internal angular momentum.
What "bulk angular momentum" is? I don't understand, why there are two angular momentum?