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I am confused as to how quasi-streamwise vortices are formed in a channel.

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Old   May 29, 2017, 07:14
Default I am confused as to how quasi-streamwise vortices are formed in a channel.
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David
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I understand, through reading some literatures, that

First, the streamwise (x) velocity gradient in wall-normal (y) direction forms the spanwise vortices. This is because the difference in the streamwise velocity produces a rotating shear force in the spanwise (z) direction. This is my understanding, if it is wrong please correct me.

Then, I also read that these spanwise vortices are lifted upwards and stretched. This led to the existence of counter-rotating streamwise vortices. The point I cannot understand is that how can the spanwise vortices create the resulting streamwise vortices?

Could anyone please explain this mechanism? Thank you very much in advance.
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Old   May 29, 2017, 07:58
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Filippo Maria Denaro
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That can be demonstrated from the Helmholtz equation written in the main reference system for grad v. The stretching term is responsible of the alignement...
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