Re: 1 billions cells: useless?
 

Sarah Palin does come across a lot like her namesake. Keep up the lip-service... :)

gorgeous bush almost ex-presidento

Re: 1 billions cells: useless?
 

Take a look at OpenFoam it work with polyhedral meshes in the mid-90: Slide 3: http://powerlab.fsb.hr/ped/kturbo/Op...shHandling.pdf

Re: 1 billions cells: useless?
 

Sarah you sound pissed!

Re: 1 billions cells: useless?
 

poly existed way before the mid-90s.

Re: 1 billions cells: useless?
 

now can you move aside and let me take charge of this thing.

Re: 1 billions cells: useless?
 

do you feel wet???

Re: 1 billions cells: useless?
 

Yessir :)

Georgeous Bush ex-Presidento

Re: 1 billions cells: useless?
 

No doubt. ASC (aka ANSYS CFX) was doing this in 1985. See CFX TASCflow. CVFEM forms a polyhedral mesh.... implicitly in the solver... :).

Re: 1 billions cells: useless?
 

Funny how you did not get your facts straight. The solver was FLUENT, not CFX. The Italy team was the only one in the top three or four not using CFX.

Re: 1 billions cells: useless?
 

OK, I read this article.

Meshing a single case with 1 billion cells and solving it end to end is a lot different than meshing a case with 1e9/40 cells and copying 40 times.

So, give me a break. What ANSYS and CD have done here is apples and oranges. Someone with FLUENT actually meshed the entire boat or keel or whatever, and solved it... not made copies of some mesh. It's totally different.

I also like the words about CCM++ "modern architecture". FLUENT has been this way for a long long time... longer than CCM++!!

Re: 1 billions cells: useless?
 

oh yes, please bring it on.

he he ....
 

we also broke a 1 billion mark record in November albiet of different sort. We spent 1 billion of campaigning alone.

Breaking into 1 billion is nothing for us. huh.

Re: 1 billions cells: useless?
 

Ok Sarah might not work for an$y$ but I think it is a safe bet that Joe does!

Re: 1 billions cells: useless?
 

Sarah these guys are pulling you. After what you have achieved i.e. one billion cells barrier, you have become a celebrity.

Re: 1 billions cells: useless?
 

Joe have you actually used ccm+? If so you will realise how ridiculous it is to compare it to fluent, I have used both and will never move back to fluent.

P.s. where is ansys 12 ;)

Re: 1 billions cells: useless?
 

"So, give me a break. What ANSYS and CD have done here is apples and oranges."

Apples: One billion polyhedral cells

Oranges: One billion tetrahedral cells a year late.

Not even the American Supreme Court or the FIA would give it to the Oranges.

"I also like the words about CCM++ "modern architecture". FLUENT has been this way for a long long time... longer than CCM++!!"

So Fluent has had a modern architecture for "a long long time". Didn't it occur to you that this fact alone means that the architecture isn't modern.

JV

Re: 1 billions cells: useless?
 

Well if someone has used both of them and understands how engineering is evolving he knows that the difference between fluent and ccm is huge. ccm is so far behind that this is not even funny.

With all the names of modern architecture all you have got is shinning GUI done is java swing. and that is just GUI not solver.

In past Fluent has been providing you with
[*] pressure based solver[*] density based compressible solver (not present in ccm)

In terms of rubustness:[*] AMG solver[*] Geometric or full multigrid (not present in ccm+)

This was in older versions of Fluent. So with modern solver ccm+ has not even caught up with old archaic solver Fluent.

And how about AMG with RPM methods to solve very difficult systems. This is very modern. Where is this type of modern tech in ccm+.

If I will start to touch models that Fluent gives you for example how about LES versions that Fluent allows you to chose. I think ccm+ does not even provide half of them.

For a modern solver ccm+ is pretty archaic. (lot of catching for them to do).

Re: 1 billions cells: useless?
 

I am not sure anyone is likely to argue that the range of physics in ccm+ are comparable to fluent, but then one code is about 5 times older than the other so that is to be expected. I admit when I first moved from fluent I was somewhat nervous for the same reason but then modern industrial cfd is so much more than just physics. And ccm+ is catching up very fast...

Fine if you want to be doing academic/R&D level type studies then I would suggest fluent may well be the way to go if there is a very specific "niche" model you need. But if you are doing the day in day out industrial cfd that modern engineering requires then ccm+ is a valid alternative (and in my case preferable). Fluent is just a solver after all, how do you prepare and mesh your geometries?

The other thing to think about is that one code has a future the other doesn't, ansys need a follow on code that will keep both cfx and fluent users happy. The fact that they are still struggling to integrate fluent into workbench, so much so they have missed their yearly release, stands testament to the problems they are having.

I think anyone who has used both and understands how engineering is evolving would know all this. Fluent user, have you used both in an industrial setting?

Re: 1 billions cells: useless?
 

hi,

i agree with what you say.

my comment was because i am seeing that people come out and rubbish fluent when compared to ccm+, and that too just because gui of ccm+ is cooler.

Re: 1 billions cells: useless?
 

It comes down to more than the GUI though. No one can argue against the that Fluent used to rule the world when it came to solver technology, but like all old software the rate of development has slowed to a crawl, especially since ANSYS try to hammer it into workbench like a square peg into a round hole.

Re: 1 billions cells: useless?
 

Google for "Wayne Smith FLUENT CCM+".

Fluent 6 was delayed by some years because a lot of developers left Fluent and joined CD-Adapco and started developing CCM+.

So ccm+ is a much newer solver than fluent developed with the combined knowledge of fluent and cd-adapco.

And is also has a coupled solver and AMG and ... Try to inform yourself before posting rubbish.

Re: 1 billions cells: useless?
 

especially since ANSYS try to hammer it into workbench like a square peg into a round hole.

This part i agree with you, i also feel after ansys has taken over, their workbench mania has done more harm than good.

In fact fluent 6.3 versions and higher are slower than 6.2 versions.

with this rate they might end up in dump.

Re: 1 billions cells: useless?
 

So ccm+ is a much newer solver than fluent developed with the combined knowledge of fluent and cd-adapco.

ccm+ newer solver and thats all. It does not mean that they have added new terms to navier stokes equations or invented new ways to descretizise it. In fact both solver has almost same implementations. But fluent provide you with little bit more options where it matters. One such example is interpolation of pressure to control volume faces, fluent gives you 3-4 options for it where as i do not see where i can even select that in ccm+. (based on documentation of ccm+ version 2.10.013 ).

And is also has a coupled solver and AMG and ... Try to inform yourself before posting rubbish.

Yaa i must admit it was my mistake to say coupled solver was not provided by ccm+. I shall rewrite it pressure based coupled solver is not available with ccm+.

Further, now how about you reread my posting, where did i say that ccm+ does not provide AMG. I said it does not provide geometric or full multigrid. (how about you informed yourself for a change this time).

Further just by saying that both provide AMG it does not mean they are same. Here also Fluent provides you with more, for example smoothing part of AMG in ccm+ has gauss siedel and jacobi. Where as you could use ILU based smoother in Fluent (other than Gauss Seidel).

Further you could use BiCGStab based multigrid (AMG), I do not see that in ccm+. And off course RCM was another useful method that is absent in ccm+ (as I already mentioned).

So new does not mean better and more. New may mean that they have some catching up to do.

At the moment Fluent has more there is no doubt about it.

Re: 1 billions cells: useless?
 

typo

it should read RPM not RCM

Re: 1 billions cells: useless?
 

i forgot to add one more thing about AMG,

Fluent gives you option of using aggregative or selective AMG methods.

(I think ccm+ only has aggregative , not sure about it though).

Re: 1 billions cells: useless?
 

OK this is getting tedious.

What you are saying is that: 1. ccm+ has a (much)better GUI 2. ccm+ is a (much)newer solver but 3. Fluent is better because it has four different options for pressure extrapolation and four different multigrid implementations.

Does it not occur to you, that having so many options, is a bad thing?

At the end of the day, what matters is producing accurate repeatable results. If, in order to get a reasonable solution, you have to resort to "voodo magic" - like changing your pressure extrapolation scheme - it's a fairly good indication that your results are solver setting dependent and neither accurate or repeatable.

This kind of manually tuned CFD engineering is all but dead, replaced by process oriented simulation, in which engineers are able to explore a design space through simulating multiple design configurations: something that you can only do with a modern GUI (see 1 above).

Re: 1 billions cells: useless?
 

Does it not occur to you, that having so many options, is a bad thing?

This is really interesting comment.

Why do you think it is a bad thing, some implementions work well in some situtations. Having more options means more versatile solver.

To appreciate what fluent provides one need to understand the benefits of those solvers.

Do you know that RPM method could be used for linear systems those could not be solved by normal AMG methods.

This thread is getting long but the things i mentioned they have their benefits and i can not write everything here.

And yaa i also forgot to mention all the fractional step based non iterative solvers Fluent provide us. (not there in ccm+)

:-D

Re: 1 billions cells: useless?
 

this thread has not only become but also , as you put it, has become tedious.

Jasak (openFOAM) and Jemcov, A published some works. Have a look :

http://www.h.jasak.dial.pipex.com/Hr...blications.bib

Probably Jasak can himself enlighten you guys why BiCGStab method precondtioned with AMG has advantages.

Or why RPM method is needed.

I think this ccm+ Fluent debate will go on, so i shall better shut up now.

Re: 1 billions cells: useless?
 

Can we have this thread stopped, or at least can a mod remind people that this forum is not a place for commerical CFD codes to be plugged.....

Re: 1 billions cells: useless?
 

You can't just stop debate about code choice commercial or otherwise. I find it very hypocritical the clear and blatant bias there is to openfoam on these boards, if a vendor posts on these boards then they are immediately shouted at for free advertising but it is fine for the fathers of foam to plug their code, say how great it is and how it can do everything you need. Bear in mind these are the same people who are profiting from Foam, not through software sales but through support and training.

If this is not a place for commercial codes to be plugged neither should it be a place for openfoam to be praised 24 hours a day.

Re: 1 billions cells: useless?
 

Have to agree with you on that one. Enough about openfoam already.

And yes, I consider 1 billion cells useless. Nice for the sake of breaking records, but beyond that, BFD.

Re: 1 billions cells: useless?
 

Open foam is useless piece of shit. If you want to get good results and get them in time, then you have to use commercial code. 1 billion cells with present technology is no big deal, but Sarah thought she performed a miracle. Bless her, she needs to learn little bit more about CFD.

Re: 1 billions cells: useless?
 

Abe, I agree with you sentiments completely.

But let me explain why I have posted about Fluent vs ccm+.

Over the last year or two, i have been listening to people on this board, who always come out and say something like - "ccm+ is new hence better". "ccm+ gui is shining hence better"

Nobody ever tells whats so great about these new solvers?

Only comments i will here is that since everyone says they are better , they shall be better.

I read manuals of CFX , CCM+ and Fluent very closely. In fact i have all the manuals of Fluent from version 5.2 and tkae lots of interest in how the solver was implemented.

Other than that i have not only read their solver part, i have tried their ways in my unstructured grid based segregated solver code. (Both Fluent's way and ccm+ way).

I found that Fluent's way is much stable. (acurate or not is another debate, but it is more stable).

What i think is people who says ccm+ is better or openFOAM is better are the people who only learn software by its GUI. The person who understands underlying maths, knows one can make other solvers behave very similar if not same.

(It means if i had to work with ccm+ i could make it work exactly the same as Fluent would have for me).

Your point about openFOAM is very valid. I do thing it is praised too much on cfd-online. But i do not use it.

I mentioned the links about jasak, because he with Jemcov (from Fluent) published some work on next generation of solvers. Where my interest lies.

(In fact I have recently come across a phd thesis, whose multigrid implementation was much better than what Jemcov and jasak did. I am spending time with it, by trying to implement it myself in my code.