# Users group on GetDP ?

Georgia Psoni and Robert Struijs gpsoni at free.fr
Wed Feb 28 22:04:45 CET 2001

```Dear Sirs,

Since short, I am a newbie user of your software GetDP.

Let me first remark that I am very impressed with the quality
and the possibilities of GetDP. I have no time to develop a 3D
code for the specific goal I'm interested in, and your flexible
way to define the problem comes in very handy. Even on my "old"
Pentium 166, a 3D problem is within reach. I have a background
in finite volume methods for aeronautical application, and I
appreciate the effort and skill you put in your program.

I was wondering if there is a users group where I can put forward
some questions. Your documentation is fairly complete, and thanks
to your examples I manage to get the computation going, but evidently
not every option is clarified in detail. Instead of bothering you,
I'd like to contact other users, keeping you as a last resort :) .
Also, occasionally I could contribute my calculations to a pool of
examples.
Perhaps also some of my notes might help another newbie user, especially

on background litterature. In aeronautics the finite volume method is
commonly used. Standard works on Finite Elements in our domain do not
treat edge based elements for divergence free solutions.
An exchange between users on the use of boundary conditions would be
quite interesting.

My actual problem is to extract an integral value from a solution.
In an electrostatic problem in a conductor, I impose the potential
at conducting surfaces, and solve for the potential in the material.
This gives me the electric field, and hence the current densities.
After reading the manual and trying many combinations of postprocessing,

I didn't manage to compute the surface integral of the current density
at the conducting surface, to obtain the total current.
Any hint is appreciated.
Also if possible some clarification on the use of the Print function
to extract the value of a variable at a certain node. I didn't get the
Printf function to work.
Since it seems I'm shamelessly presenting my wish-list, a detailed
example on the network options would be welcome.
I like your explanation on p. 13 of "Dof" ; on the other hand, I can
only
approximately understand the terms 0-form ...2-form on p. 44 (section
4.4).
What is meant by a 3-form is quite a mystery. Do you have some
references
for an interested engineer ?
Are examples available for the use of the Green functions, section 4.2.3
?
Do you have an example on how to use your gnuplot files with gnuplot ?
Gnuplot is a software I don't use very often, and I didn't manage to
the files.

As a side remark, I didn't find the files mentioned in chapter 6
of the manual on the webside, so I extracted them from the .pdf version
from the manual (version 0.76).
It appears that there is just a typo on p. 65 in Jacobian_Lib.pro :
"JacobianMethod" should be "Jacobian".

Just for curiosity, I was wondering if you plan to include upwind
biased weighting functions for the computation of fluid dynamics.
I have no intentions to use it in the near future, it is just
that I have been working in a related field.
Another question is if you plan to issue parallel versions of the code,
either in multi-threading or using a parallel library ?

I apologize for the long mail and many questions, but I send you these
remarks in an effort to contribute constructively to your very useful
software.

If I can be of help assembling some documentation for new users like me,

I'd be willing to put in some effort.

Sincerely Yours,

Robert Struijs

28, Av. de Gascogne
31170 Tournefeuille
France
e-mail : gpsoni at free.fr

```