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velocity profiles of pipe and annulus

Posted 2011年8月17日 GMT-4 04:53 4 Replies

Michael Rembe Certified Consultant
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Hi,

I have bad convergence using a constant velocity (v=Q/A) for a pipe inflow.

Using a parabolic velocity profile I get excellent convergence! The formula is v=2*Q/A*(1-r^2/R^2) with:
r - space coordinate of an axisymmetrical model
R- pipe radius

Does anybody know the formula of the velocity profile of an annulus (axisymmetrical model)?

Thanks
Michael
4 Replies Last Post 2011年8月18日 GMT-4 02:37
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 2011年8月17日 GMT-4 06:14
Hi

in laminar regular flow for an isotropic model its approaching a parabola, that explains probably why you get a better convergence starting closer to the final solution

--
Good luck
Ivar
Hi in laminar regular flow for an isotropic model its approaching a parabola, that explains probably why you get a better convergence starting closer to the final solution -- Good luck Ivar
Michael Rembe Certified Consultant
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Posted: 1 decade ago 2011年8月17日 GMT-4 06:24
Hi Ivar,
yes, this is right. But now I'm looking for a velocity profile (laminar flow) for an annulus (two pipes into one another).

The formula should be similar to v=4*v_max*s*(1-s) in 2D, but just for a 2d-axisymmetric model

Michael
Hi Ivar, yes, this is right. But now I'm looking for a velocity profile (laminar flow) for an annulus (two pipes into one another). The formula should be similar to v=4*v_max*s*(1-s) in 2D, but just for a 2d-axisymmetric model Michael
Lechoslaw Krolikowski
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Posted: 1 decade ago 2011年8月17日 GMT-4 13:55
Hi Michael,
Attached is the velocity profile you are looking for.
BR
Andrzej
Hi Michael, Attached is the velocity profile you are looking for. BR Andrzej
Michael Rembe Certified Consultant
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Posted: 1 decade ago 2011年8月18日 GMT-4 02:37
Hi Andrzej,

thank you very much for the velocity profile!

Best regards
Michael
Hi Andrzej, thank you very much for the velocity profile! Best regards Michael

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