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 sara September 4, 2008 15:35

axisymmetrical flow

Dear my friends

I want to validate my result in two dimentional laminar axisymmetrical flow.but my result show center velocity(umax) is 1.5 mean velocity(umax=1.5*umean).I read in fluid mechanic references in internal laminar flow in pipe that respect is 2 (umax=2*umean). could anyone tell me axisymmetrical flow's result is equal to intennal flow in pipe and what is correct result.

best regards sara

 ag September 4, 2008 16:32

Re: axisymmetrical flow

For a laminar pipe (assuming no variation in the circumferential direction) the max velocity is twice the average velocity. This result can be found in a closed form solution (see for example Fluid Mechanics by White).

 sara September 5, 2008 00:41

Re: axisymmetrical flow

I want to know 2d axisymmetrical flow calculation's result is equal to 3d pipe flow result.help me many tanks

 ag September 5, 2008 08:46

Re: axisymmetrical flow

If you are running a 2D axisymmetric laminar calculation, then the max velocity should be twice the mean. If you have fully 3D flow (with nonzero velocity components in all 3 directions) then the max velocity may not be twice the mean.

 sara September 5, 2008 09:42

Re: axisymmetrical flow

dear my friend thanks for your paid attention for my case.could you calculate max velocity twice the mean. i can't .i calculate 1.5.

regards

 ag September 5, 2008 15:02

Re: axisymmetrical flow

I don't understand what you are asking for here - the classic laminar result is that the max velocity is twice the mean, whether I compute it or not. I don't have your code, so I have no way of determining where your error is. I would suggest that you first make sure that the velocity profile has a parabolic shape. If your velocity profile is correct, then the error may be where you compute the average velocity.

 sara September 6, 2008 08:11

Re: axisymmetrical flow

dear my friend

my result show umax/umean=1.5.for this reason i am not sure result . my velocity profile is parabolic .if is possible send me your email then i send velocity profile for you .

regards

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