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Markus March 27, 2007 09:11

poor postprocessing in Fluent
Hi there,

Im working on time dependent simulations and i want to make time dependent postprocessing just like animations and mpg`s.

It is not possible to use Fluent for that work, because the animation software contains so much bugs, that it is not possible to use it.

What the hell is that animations tool for, when it doesn`t work.

Why do we have lots of different models for calculation, when its not possible to produce good animations or graphics.



John b March 27, 2007 10:32

Re: poor postprocessing in Fluent

I completely agree. The user interface in general is excruciatingly bad and is non intuitive. The help files are the most unhelpful files I have ever came across. They're poorly written, badly organised and unclear. I'm trying to do animations just now but I am not getting anywhere fast.

I see fluent as a rusty old land rover with tattered seats and crisps and empy coke lying about the back seat. It doesn't look, handle or feel good. It's been about for a while and has just been patched up all this time. But, under the hood it's got a solid engine and can take you most places if you know how to tinker with it.

I use 3 FEA packages - FLUENT, ABAQUS and COMSOL (formerly FEMLAB). Out of the three, the best package I've used overall, by a long way, is COMSOL. It's strengths are fluents weaknesses and vice versa. It's a memory hog and the meshing is awful and I have no idea what's going on when it's solving (no residual monitors etc) but it's cheap and the help and support is the best I've seen. I use their help files to help me with fluent! They give 100% support for academics. I've got one of their support technicians on fast dial. I've even had lunch with one of them! For just now, I have to put up with fluent because its more robust for what I'm doing. If COMSOL sorts out these problems i.e. meshing, memory hogging, cpu parellelisation and control over solution (I've already seen large improvements in the last 6 months), I'll jump over to them faster than a frog on a hot skillet. Until then.. I feel your pain.

jasond March 27, 2007 16:20

Re: poor postprocessing in Fluent
While I agree that the stock animation setup is little on the buggy side, I don't agree with your assessment of the documentation or the user interface. I have seen way worse on both counts.

On the original post about the animation - the best idea to get good results is to burn storage like there is no tomorrow. I never ask Fluent to generate the movie file - I always generate hardcopy pictures (individual movie frames) and then assemble the animation outside of Fluent. For a recent animation that I made, I generated a frame (as a PPM) every timestep and then saved the solution every 10 timesteps. It took up a lot of storage, but if anything went wrong, it would not take a lot of effort to get to a particular timestep.


efra March 28, 2007 04:27

Re: poor postprocessing in Fluent
thats rigth jasond.

I save every certain time steps for unsteady simulations. and then I write a Journal that automatically reads stored data one by one. For exaple the journal reads file 1 ( t=0 s) then it displays contour of pressure on walls and it can even anotate flow time, make transparent walls, translate walls, overlay pathlines with isosurfaces, etc,etc.

You can make journals to write a Hardcopy for every file it reads, then I use a program called ImageToAVI (free on the net) and create high resolution animations.

tip: Export jpg´s to width and Height 3 or 4 times larger than your window size (as exported using Height and Width set to 0) and then use some standard image editor to reduce the image size back to the fluent size. It works fine!



Dr. Flow Squad March 29, 2007 07:10

Re: poor postprocessing in Fluent
Here is a tool for creating perfect animations out of hardcopy files. Just skip point 1, since it is written for CFX. Remember not to make your hardcopy files as JPEG's but use PPM instead. (Better would have been PNG but that's not supported by fluent).

- Dr Flow Squad

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