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parabolic flow derivation
Posted Jun 10, 2010, 6:17 a.m. EDT 3 Replies
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dear all
i'm particularly new to comsol, and currently using comsol 3.3.
i'm interested in the fluid dynamics side of things, and understand that comsol uses this equation as the boundary equation for initial velocity (if using the inlet velocity) to describe a parabolic flow:
4*vmax*s*(1-s)
the multiplier is 6 if using vmean.
my question is: how is this derived? i know how the equation for a steady state flow in a circular pipe looked like, and it's nothing remotely similar to the above equation. and what is 's', by the way?
thanks for reading.
-nahrizul
i'm particularly new to comsol, and currently using comsol 3.3.
i'm interested in the fluid dynamics side of things, and understand that comsol uses this equation as the boundary equation for initial velocity (if using the inlet velocity) to describe a parabolic flow:
4*vmax*s*(1-s)
the multiplier is 6 if using vmean.
my question is: how is this derived? i know how the equation for a steady state flow in a circular pipe looked like, and it's nothing remotely similar to the above equation. and what is 's', by the way?
thanks for reading.
-nahrizul
3 Replies Last Post Jun 12, 2010, 5:13 a.m. EDT
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Posted:
1 decade ago
It is to enter a parabolic velocity profile:
bit.ly/a6Etlu
s is the Arc Length parameter. Take a boundary line, 0 is the beginning of the vector and 1 is the end of it. Something like y/H.
bit.ly/a6Etlu
s is the Arc Length parameter. Take a boundary line, 0 is the beginning of the vector and 1 is the end of it. Something like y/H.
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Posted:
1 decade ago
hi danial
thanks for the quick response :-)
thanks for the quick response :-)
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Posted:
1 decade ago
Hi
Just check regularly that "s" is really going from 0, to 1, this is MOSTLY the case, but I have had some surprises !
in 3D with s1, s2 its slightly more complex, and one should there too check regularly the ranges
It's just to plot "s" along the arc
Note that with V4 there are sometimes changes in the directions (flip of 0, and 1) w.r.t. 3.5 and the depending on the geometry, old habits should be renewed/updated with V4 ;)
Have fun Comsoling
Ivar
Just check regularly that "s" is really going from 0, to 1, this is MOSTLY the case, but I have had some surprises !
in 3D with s1, s2 its slightly more complex, and one should there too check regularly the ranges
It's just to plot "s" along the arc
Note that with V4 there are sometimes changes in the directions (flip of 0, and 1) w.r.t. 3.5 and the depending on the geometry, old habits should be renewed/updated with V4 ;)
Have fun Comsoling
Ivar