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Hairpin vortices in turbulent channel flow using DNS |
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November 21, 2016, 17:06 |
Hairpin vortices in turbulent channel flow using DNS
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#1 |
New Member
Nitin
Join Date: Mar 2012
Location: Bombay
Posts: 16
Rep Power: 14 |
Hello Foamers
I am performing DNS of turbulent channel flow to understand the relationship b/w hairpin vortices and heat transfer associated with it. In the literature, the formation of hairpin vortices is explained as follows: First of all, vortices formation in spanwise (z) direction due to gradient of streamwise velocity (du/dy) in wall normal (y) direction. Stretching and lifting of spanwise (z) vortices results in two counter-rotating vortices in streamwise (x) direction. These vortices elongate further in x direction and eventually connect at y+=15 and results in formation of hairpin. I am not able to understand the driving force behind stretching and lifting? Please share your experience and understanding. |
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November 21, 2016, 17:40 |
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#2 | |
Senior Member
Filippo Maria Denaro
Join Date: Jul 2010
Posts: 6,892
Rep Power: 73 |
Quote:
to understand this issue, start from the Helmholtz equation for the dynamics of the vorticity. The key is in the term (w. Grad v) that is non-vanishing in 3D. Such term (stretching term) is responsible for the alignemnt of the vortex tube along the stream-wise direction and the reduction of the tube section. |
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November 21, 2016, 18:52 |
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#3 | |
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Jingchang.Shi
Join Date: Aug 2012
Location: Hang Zhou, China
Posts: 78
Rep Power: 14 |
Quote:
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