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-   -   Periodic flow boundary condition problem (http://www.cfd-online.com/Forums/fluent/33591-periodic-flow-boundary-condition-problem.html)

 sudha April 27, 2004 08:33

Periodic flow boundary condition problem

Hi folks,

I am solving unsteady heat transfer problem in FLUENT. My problem I allowing to pass the coolant thru 650 channels thru a rect. wall cut in a such way tht thr will some solid portion in the wall thru whch conduction is taking place .coolant is taking heat load frm both the top and bottom walls.

so I have modeled the problem by taking one the channels. (i.e. 2 halfs of the cvty and 2 solid walls) so at the end I have specified Periodic B.C. at each end. I have exported mesh succesfully in FLUENT.

so for periodic condition it will ask for spc mass flow rate which I have given total mass flow/650*2 since only half portion of cvty is taken. So is it correct?

for pressure I have specified 10 pa/m value. and other things like relaxation and iterations I ve taken default values.

but after initialzing I am getting "segment Violation" error. so wht may tghe problem? and also I am wondering how FLUENT will take care of all flow thru 650 channels? tht means computations of all geometry. I am totally confused with this.

I have trying to find solution for this problem but i couldn't?

could u plz shed some light on this problem.

could somebody give me more explation on this periodic flow problem?

any help is appreciated.

will w8 for ur suggestions eagerly.

 Trilok April 28, 2004 06:09

Re: Periodic flow boundary condition problem

For your query no.1(mass flow rate) Yes it is the correct way of giving boundary consition..If you can explain the problem more clearly i may help.Take some time and write the problem clearly.plz dont use short cuts in your words..very difficult to understand ur sentences.. Trilok

 sudha April 28, 2004 08:16

Re: Periodic flow boundary condition problem

Hi users, I am really stuck on this problem. plz help me out. plz send me tricks.

 sudha April 28, 2004 08:40

Re: Periodic flow boundary condition problem

Thanks trilok for ur response. I have a wall (of dimensions1 by 0.01 by 1.85 m. cavities of size 6 by 1 mm are cut along 1m length). through cavities I am allowing the kerosene to pass through it . there is solid thickness of 2 mm on either side of the cavity.

So I have modelled half cavity from each side and in between thses two halves solid thickness of 2mm is present.

I have linked extreme two walls in gambit and defined it as a periodic boundary condition (in GAMBIT) itself.

then I exported the geometry to fluent successfully.

I have defined translational periodic boundary condition.

I have specified mass flux of 0.0008 which total mass flow rate/no. of channels * 2(since i have taken half portion of cavity that's 2 is appearing)

but my question is , 1.how FLUENT will take care of all 650 cavities which I have cut along 1 m length? (as it is not asking inputs like no. of cavities or total lenght or frequency of periodic boundary conditions.this i bothering me) 2. FLUENT is giving "SEGMENTATION VIOLATION" error at the start of first iterration. it is bcoz of wrong specifiacation of boundary conitions or wrong modelling of the problem. I don't know. To solve this prob. i specified each every boudary condition separately . and different types like Interior,Internal instead of wall. but I am getting same error again and agian.

so where is the bug I am unable to locate.

so kindly look at the mail. thanks in advance. regards.

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