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-   -   [ICEM] Learning strategy (http://www.cfd-online.com/Forums/ansys-meshing/94097-learning-strategy.html)

TheBearJew November 5, 2011 03:36

Learning strategy
 
Hi all!

I would like to ask to the more experienced users some tips on ICEM learning strategy.

I am quite new to CFD meshing and I am trying, and I am sure I will, to learn it by my own.

I want to use ICEM CFD for setting up grid for external flow simulation.

Well, I am quite inside Computationl Fluid Dynamics and Grid Generation Principles and Philosophy but when I make Tutorials it seems I am a monkey-like doing things without understanding them.

So the real point is, what's the best reference to get inside ICEM CFD in a such "theorical way", something better than ICEM User Manual and Tutorial.

cdegroot November 6, 2011 10:53

Quote:

Originally Posted by TheBearJew (Post 330800)
So the real point is, what's the best reference to get inside ICEM CFD in a such "theorical way", something better than ICEM User Manual and Tutorial.

I wish I could have found what you are looking for! ICEM's learning curve is steep, but it does produce excellent meshes when you finally figure out how it works. To be honest, the way I learned ICEM was through doing all of the tutorial problems and then struggling through meshing the geometries I was interested in (while referring back to relevant tutorial problems and the user manual). There was a lot of trial and error. If you get stuck talk to someone who knows the problem or post to these forums.

Far November 6, 2011 11:41

If you plan to use the structured meshing, then I suggest you to practice Hexa tutorials, may be two to three times each. In this way you will get hold of the basic commands and how ICEM works (If you term this as monkey like, then I am happy to tell you that I learned many things in this way :p) Then move to your problem and try to make a base mesh and then try to increase quality. IF you get the problem , you may ask for help from ICEM support, your colleagues and/or post your problem with some pics here. But with patience because good meshing is more a art then science.

Far November 6, 2011 11:44

Quote:

So the real point is, what's the best reference to get inside ICEM CFD in a such "theorical way", something better than ICEM User Manual and Tutorial
If some one wants to learn Chinese then who would be the better language teacher than Chinese?

TheBearJew November 6, 2011 12:20

Thanks for the answers.

And your saying is supporting me cause it is what I'm doing.

Probably I overreact when I have to cope with new difficulties trying to learn as more things as possible in the less time I can.

Often new concepts just need time to be completely comprehended.

Far November 6, 2011 13:01

I should have been more polite :) Actually it is lot easier to learn gambit or Gridgen which are based on bottom up approach and gives you pretty good meshes. You can see many journal papers with these meshing tools.

Even I have six plus years experience of CFD with meshing in gridgen and gambit, but still I find it difficult to learn ICEM CFD. Becuase to decide where to split the block and where not to, a priori, is very much difficult. But once you learn it you would be able to get a very good high quality mesh in very less time. ICEM CFD's O-grid blocking is very strong feature as compared to gambit and gridgen. Since to create O-block manually around a 3D complex geometry is very much difficult.

PS. I would like to suggest you to take a look on GridPro, which is based on same philosophy but with very excellent quality meshes. Also it has many advance features like nesting, wrapping, automatic mesh smoothing based on some proprietary algorithm and many advance features which ICEM CFD does not posses.

sameben December 21, 2011 06:25

If you are from the academia, you can request for a free copy of GridPro!

Far December 21, 2011 06:51

Quote:

If you are from the academia, you can request for a free copy of GridPro!
Yeah but for one month and 250 blocks limitations. :p And you know GridPro creates too many blocks even for simple 3D airfoil (with unit depth) you may end up with more than 250 blocks

sameben December 21, 2011 07:21

Yes Far,its a 250 block version, but the duration is 1 year!

PSYMN December 22, 2011 13:04

Commenting on Fars comment about Gambit and Gridgen being easier to learn...

I would say you are experiencing a paradigm shift. After putting in so many years with certain tools, it can be very tough to make that shift.

ICEM CFD is a top down hexa mesher and those others are bottom up. I have demonstrated many times that it usually takes much fewer steps to get where you want with a mostly top down approach (ICEM CFD also has the option to do bottom up, but I use it sparingly). And the ICEM CFD Ogrid tool makes that even more clear.

If you start in a bottom up world, it is a tough mental shift to go to the top down one.

We see the same thing in the other direction. ICEM CFD users who try Gridgen or Gambit often complain about how hard it is to learn. Again, I think they are mostly getting stuck on the paradigm shift.

The trick in migration is too keep your understanding of what a good blocking looks like and accept that you will be using a different philosophy to get there.

As for Gridpro, it doesn't offer nearly the control or quality of ICEM CFD or Gambit, but automation is nice when it works.

Far December 22, 2011 13:38

Quote:

ICEM CFD also has the option to do bottom up, but I use it sparingly
How to use this feature and can we use both features at the same time i.e. top down for main block and then adding the few special parts in blocking through bottom top approach.

PSYMN December 22, 2011 14:59

Sure, look at the options under Blocking (tab) => Create blocks.

You could to top down for most of it, and then pick any face you want to extrude out a block. Or you could create a block from verticies to fill a tight spot in an otherwise top down blocks. Or you could take some blocks and copy/rotate them around. Or your could start with 2D blocking (created top down) and extrude/revolve that from 2D to 3D. Or you could load two separate blocking files and go from there.

Lots of options really. It is possible to work completely top down, but then the index control is useless and you run into other hassles and issues.

The problem is when users start this way because that is how they have always done it. They often think ICEM CFD Hexa is hard, but they are missing all the faster and easier to use top down tools like split block, Ogrid, etc.


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