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-   -   Please help!.... (http://www.cfd-online.com/Forums/fluent/30209-please-help.html)

Deadly August 25, 2002 05:49

Please help!....
 
Dear all,

Recently i iterated a half model duct using symmetry planes..but i wasnt sure if my symmetry method produces the same results as my full model... so i decided to try quartermodel of the duct applying symmetry planes again to see if i can achieve the same results as the half model. I stopped ierations halfway to see if they gave somewht the same profiles as my half model but i realise tht they dont... By right, i should be able to get the same results as my half model if i iterate quarter model rite? Plz shade some light on this.. Thnk you

puck

sri August 26, 2002 14:26

Re: Please help!....
 
Hi,

It is always reasonable to compare two converged solutions.I understand this is not so from your notes.Definitely Fluent should give same results provided there are no fluxes across the symmetry plane.

Regards, sri

Deadly August 27, 2002 01:30

Re: Please help!....
 
How to i check whether there are any fluxes across the symmetry plane?

Plz reply...Need to know urgently:P

Puck

sri August 27, 2002 03:08

Re: Please help!....
 
a symmetry plane implies there are no fluxes across it.If there are then the problem formulation is wrong.Anyhow you can check the fluxes through

report -->fluxes in fluent.

hope this helps you

sri

Deadly August 27, 2002 10:24

Re: Please help!....
 
U mean i check have to click the symmetry plane...then go to "report" and check fluxes?

benji August 27, 2002 11:35

Re: Please help!....
 
if i don't make mistake, you must define in your full geometry a plane like the symmetry. If their is no fluxes through this one, you can define as a symmetry.

Sridhar September 3, 2002 10:50

Re: Please help!....
 
Hello,

A little more light on this issue. Generally, if there can be any swirling flow(or in Sri's words- if there is any flux across that plane) near the plane of symmetry (as you call it), then in principle you cannot use a symmetry BC for that plane. You can rather use a periodic BC. Moreover, even periodic BC will not suffice sometimes, say, if you are doing something like a multiple jet problem(in this case your domain needs to have at least two or three of such multiple jets to adequately capture their interaction). So please check out if you have any fluxes/sudden change in the flow phenomenon across the plane. If yes, symmetry is not a good Bc to use. Hope this helps.

Regards, Sridhar.


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