Richard,
As with all modeling methods the choice of step size is the key to
convergence to credible results.
From my experience, unless the computer runtime is very large,
running the simulation with decreasing step size and watching the difference
between runs until a reasonable difference (maybe ooo 10-3 or smaller) is
achieved.
In the olden daze, I worked with a program that took 4 or 5 cpu
hours to converge to a reasonable result and we were limited to 1 cpu hour
per nite by the computer center folks on an IBM 370 so we could run one case
per week - which, by today's standards, seems horribly slow. (Plus my
laptop has more computing horsepower today than that machine).
At best, you will be able to run a simulation in a few minutes per
case; at worst, you might have to lite it off and go to bed and look for the
results in the morning (which I have seen done).
Anyway, have fun chasing your result. Simulation has become such an
important part of engineering practice. I'm absolutely amazed at what is
being done today - not only for traditional electrical circuit design
analysis or mechanical design analysis but now for thermal analysis or emc
field analysis. Not like the olden daze BC (= Before Computers) when we did
all of the calculations with a sly drool (ooops, slide rule) and used a
burnt stick to record the results on a scrap of paper. I remember as a
graduate EE student asking an old-timer electronics designer how much he
depended upon writing PDE circuit equations an solving them; his response
was that it was all too difficult and time consuming so the methodology
depended upon rules of thumb which guided him to make changes in circuits
and measuring the improvement/change then reiterating again. (It seems
easier to do this with my computer than breadboarding it). But these guys
drove astounding changes in electronics business with this trial and error.
So much for the ramblings of another OF (Old Fellow, in polite
company.
:>) br, Pete
Peter E Perkins, PE
Principal Product Safety Engineer
PO Box 23427
Tigard, ORe 97281-3427
503/452-1201 fone/fax
[email protected]
-
This message is from the IEEE Product Safety Engineering Society
emc-pstc discussion list. Website: http://www.ieee-pses.org/
To post a message to the list, send your e-mail to [email protected]
Instructions: http://listserv.ieee.org/request/user-guide.html
List rules: http://www.ieee-pses.org/listrules.html
For help, send mail to the list administrators:
Scott Douglas [email protected]
Mike Cantwell [email protected]
For policy questions, send mail to:
Jim Bacher: [email protected]
David Heald: [email protected]
All emc-pstc postings are archived and searchable on the web at:
http://www.ieeecommunities.org/emc-pstc
______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please visit http://www.messagelabs.com/email
______________________________________________________________________
