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kk February 15, 2007 17:33

laminar flow mechanism
Does anyone have the information on how Fluent deal with laminar flow? I've been trying to look for laminar modeling equations in Fluent USER's Guide line but could get anything yet.

Freeman February 15, 2007 17:59

Re: laminar flow mechanism
well what do you mean by 'laminar modeling equations'? fluid flow is either laminar/turbulence. so during problem definition if none of the turbuelnce models is turn on, it automatically assume the flow to be laminar. Thus only solves the N-S for u,v, and w, and any other equations being energy or etc. Check their tutorials, I think they've sample problem and then you can follow individual links.

all the best

kk February 16, 2007 00:42

Re: laminar flow mechanism
How does Fluent treat the wall area when I use laminar then?

zxaar February 16, 2007 00:55

Re: laminar flow mechanism
this is the mystry question. I also need to know the exact answer to this, manuals do not mention it clearly.

Freeman February 16, 2007 17:35

Re: laminar flow mechanism
i'm not sure what you use to generate your grid. as does most commercial CFD codes( fluent, etc.) any area not specified with bc, a default boundary which is wall is assumed. if you use GAMBIT as your grid generator, you should have specified all your 'important' bcs there, although they can be changed in the fluent too by selecting, boundary->boundary name->etc. so, any surface which is given any type of boundary, when it's exported to fluent, wall be assumed for that. you can always check this in fluent. I'll advice that you do grid check in fluent to see if all your surfaces are well defined including volume domain, etc.

Now back to your question, once again, what do you mean by 'wall area'? Laminar is laminar. unlike turbulence where wall treatment is the key aspect, especially your yplus value, in laminar flow it's not a key parameter and might even 'exist'. you might want to refine the mesh close to the wall espcially if there're a lot of curve areas. be sure that you don't have negative volumes though, since fluent solver might complain about it. also, it'll be equally better off to do 'global' grid independence test instead. There's no special wall-treament or equation solves for the wall-area as I know off from fluid mechanics and let alone found that in CFD code. I might be wrong but you could cross-check it from either Fluent support/fluent's forum, or other sources. I hope this helps.

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