Difference between 2.5D and 3D simulation tools?

[wangyan]

in the realworld , there is no 2.5D object. I thought 2.5D=2D+line, that is, 2D move around line ; the shell of trajectory is 2.5D;

 

[rautio]

Hi Wangyang -- As for definition of 2.5-D see my first posting above (way back there!). I notice the article I posted is no longer there, don't know if I did something wrong or what. If you send me an email, I will reply with the article attached if you like.

Also incidentally, one thing that is the same about 3-D arbitrary and 3-D planar (what some people like to call 2.5-D even though the term has problems in this use, as described in my paper) is that they all fail to analyze real world objects, and they all give the wrong answer.

(Wow! Did Rautio really say that?) Yes I did. They all give the wrong answer. The only question we can hope to answer is how much wrong the answer is. All computer modeling is an abstraction from reality. It is not and never will be reality. It can only give us a hint as to what will really happen when we really build it.

To answer the question of how wrong is it, we can use handwaving discussion to indicate possibilities in a most general and uncertain fashion. If one stops there for a real project, one is not doing engineering and does not deserve the title of engineer. If you want to do engineering, when things like "How wrong is it?" are important, you have to do numerical experiments and quantify it. Engineers (real engineers) want numbers. But quantifing error is another topic and I have quite a few papers on that if people are interested, feel free to start a new topic. -- Jim Rautio

 

[loucy]

Among other things, Dr. Rautio must be referring to the stripline benchmark problem for which we can find interesting and impressive details on Sonnet's website. Anyone using EM solvers shouldn't miss that.

In the reference list (on Sonnet's website), there are two papers (letters in a column about MIC simulation in IJMMW) whose titles suggest some exchange with Zeland on the problem. I think that must be very interesting, but unfortunately I don't have access to those volumes of the Journal. I would deeply appreciate it if Dr. Rautio or some one else can post the relevant materials here.

I notice that EM3DS offers an example on simulation of thick stripline, which I don't see being discussed on Sonnet's website. Obviously the purpose of that example is to show the accuracy of EM3DS' 3D model. The conductor is however perfect, thus the currents stay on the surface and the reuslt of that example doesn't say too much about the 3D model. It would be very interesting to compare the results for a thick lossy stripeline between Sonnet and EM3DS.

 

[cheng]

Loucy, I agree with you that a good comparison would be to compare the thick lossy stripline and other structures with Em3DS, Sonnet and possibly others. I can run the Em3DS sim and present results here if someone is interested. but we have no access to Sonnet, hence, someone else should run that part.
Please let me know.

Best regards,

Cheng

P.S I can also run in 2.5D mode (em3ds) and compare too should that be of interest to anyone.

 

[rautio]

Hi Loucy -- Sorry for taking so long to reply, I just got back from travel. Will be very pleased to discuss this topic further, but I think it is maybe a bit off topic now. Perhaps you would be willing to start a new topic with your comments above. It would also be helpful to do that for those who are not interested in surface vs volume meshing but are interested in accuracy and error in EM analysis.

Hi Cheng -- Please re-post your comments on the new thread as well. I think I have some useful information for you, including a nearly exact solution for lossless thick stripline.

I will throw in one comment that is way off topic: My travel was to present a lecture on the life of James Clerk Maxwell at Purdue. If you have a chapter of the IEEE near you and you would like to have me visit, go to www.mtt.org and click on New DML Lecturers for 2005.

 

[loucy]

Thanks a lot. Dr. Rautio. Please go to