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Re: 3D version of ETesla

Original poster: "Mark Broker" <mbroker@xxxxxxxxxxxxxxxx>

On Thu, 07 Jul 2005 18:16:36 -0500, Tesla list <tesla@xxxxxxxxxx> wrote:

Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Mark,

The constraints are trivial.

I took "me" weeks to get it right 0:o)

Well, to be honest, all the hard work has already been done! Now it would really just take what is already done in ET6 and revolving it around the coil (Z) axis. The "special boundaries" would be set up using some simple boxes and spheres that could be inputted using dialog boxes or something (no hard coding necessary).


(IIR, it made the code harder to read, so speed was sacrificed in the name
of readability.)  It's also possible to use fixed point math using
integers, which "may" crunch faster than floating point numbers.


In this case, the "idea" of the program is now fairly well understood and
known.  Now, we need speed!!!  I used to set the alarm to wake me up at
3:30am so I could load the next test E-Tesla BASIC model on the
laptop...  Now the computer can do that model in 15 seconds!!!  I now run
500 x 500 arrays like it is no big deal!!!

I remember the first time I ran it in ~March of 2000 I spent about 3 hours on "medium acuracy" on my Athlon 500. I think everyone who uses it is grateful for the speed improvements!


The "display" is the hardest part for sure!!!  No "free" program I know of
can do it well, if at all...  Slices are fairly easy if you like
math....  The different OS GUIs get messy now too...  StarOffice, Excel,
MathCad...  are pretty easy to use and can be "found" by many...  I note
that the fancy video card in my computer with it's eight processors and
massive fan and power needs can run video games fine even with two models
running and using 100% of the hyperthreading CPU...  Not sure if the "video
card" could just "do it"....  That takes more computer knowledge than I
will ever dream of having...  I think the video cards are OS/CPU platform
independent at least...

No need for fancy video stuffs. Basically at the end of computations there will be this 3-dimensional array that we want to view. Therefore a plane would have to slice through the 3D grid to produce a 2D grid that would form a surface plot. Basically, slice the 3D "box" to create the 2D "square" that ET6 spits out. That isn't super tricky. The "hard" part is realistically defining the cutting plane. (FWIW, *all* of the good CAD packages will automagically project 2D views of a 3D solid, and many have been doing so for decades.)


To date I can only recall three instances where I could have used a 3D
version of ETesla - I was wondering how the proximity of a grounded rod
would affect things, I was wondering how a radial streamer/spark affected
the tuning, and yesterday when I was wondering what the potential of a
"floating" object would be.


That "floating" potential things is messy for sure!!!  I have no idea how
that would be handled....

Basically the control grid would have a unique value for a floating object in which adjacent cells would be averaged and the average applied to all the cells. I did this as a Laplacian surface experiment in the spring or fall of 2000 (in MathCAD!).


Maybe iterate the 500 x 500 x 500 array 250000 times :o)))

Perhaps with some careful grid setup, the number of iterations could be significantly reduced. I believe I had suggested that about ET6 while it was still a BASIC program (no pun intended!)


Next is to make the program handle "dynamic" cases....  That
will easily blow today's computers clean out of the water...  Have to hook
up a massive parallel array of old GameBoys or something...

My head hurts to merely think about a dynamic case. Massively Parallel Array of GameBoys - that's pretty funny! :o)


"I" don't think it is worth it...  I just don't see the great need and I
can't imagine the end resulting program that we could use...  A direct test
or experiment could provide the answer in the rare cases far faster...  It
would "be cool to have", but I just can't see the great need...

Indeed, this is the answer I expect from most on the list - "fun" idea with some use, but too much work for the result.


As an afterthought I had just as I was about to click the send button,
this really is just a standard FEA problem.  Although I don't know of any
free FEA applications out there, there are discounted student copies (and
illegal copies) of many of the commercial ones.  Has anyone thought of
and/or looked into this?


It has been about 9 years now since I played with any and they "might" have
made them better since :o)))  I played with Algor back then...  But it was
all thermal and mechanical stuff...  If there is a good commercial package
that would do the trick, there might be someone out there that could run
the "one problem" a year through it for us...  This recent problem of
Dave's is pretty cool!!

I don't have any direct experiences with electrostatic FEA packages. I had an ME class on FEA in school, which featured Algor (using the book the prof wrote on the subject). I believe that Algor had a "button" for electrostatic analysis, but I never tried it. I'm looking for a "free trial copy" of Algor 16 to see what it can do.


The advantage of having our own code is that we
can modify it just the way we want like ScanTesla...

In reality, the part unique to "us" is setting up the Tesla Coil boundary conditions, which we have done in ET6 to spectacular accuarcy. Pretty much "all the rest" is "standard FEA stuff."


Cheers!

Mark Broker
The Geek Group