[Gmsh] ... electric field lines ...

[Christophe Geuzaine]

Matt Koch wrote:
> Hi All,
> 
> this seems to be a simple matter of solving the following equations for 
> F = (Fx,Fy,Fz) as the vector (yeah right, NOTHING is EVER simple):
> 
> dx/ds = Fx/|F|
> dy/ds = Fy/|F|
> dz/ds = Fz/|F|
> 
> with |F| = sqrt(Fx^2 + Fy^2 + Fz^2)
> 
> Even a dumb Runge-Kutta approach could probably do. I might could give 

Isn't this pretty much what we do in Plugin(StreamLines)? There we
solve dX(t)/dt = V, with X(0) chosen as a bunch of points in space and 
V(x,y,z) interpolated from the vector view.

> it a try, but I'd need to know how to write plugins (how to 
> programmatically access fields calculated by GetDP, how to 
> programmatically draw in GMsh, and such), and perhaps get some feedback 
> from y'all on how long it might take to write a "typical" plugin? Would 
> some sort of Runge-Kutta driver or other ODE solver be accessible to a 
> plugin, or would that have to be developed from scratch, or pulled in 
> from GSL, for example?

Have a look at Plugin/StreamLines.cpp in the Gmsh source code: you'll
see that it's actually pretty simple to write a plugin.



> 
> Thanks,
> 
> Matt Koch
> 
> 
> Christophe Geuzaine wrote:
> 
>> Matt Koch wrote:
>>
>>> Hello there!
>>>
>>> what a wonderful program GMsh is! It takes a little while to get used 
>>> to its GUI, but once you get the hang of it, it is extremely useful 
>>> and intuitive! However, one thing I have not been able to figure out 
>>> yet is how to make electric field lines from an electric field vector 
>>> solution. I looked into the StreamLines PlugIn, but that seems to 
>>> only work off of a velocity field. Any thoughts?
>>
>>
>> Maybe this could be a good idea for a new plugin?
>>
>>
>>>
>>> Thanks,
>>>
>>> Matt Koch
>>> mattkoch at scitex.us
>>> www.scitex.us
>>> _______________________________________________
>>> gmsh mailing list
>>> gmsh at geuz.org
>>> http://www.geuz.org/mailman/listinfo/gmsh
>>>
>>
>>
> 


-- 
Christophe Geuzaine
Assistant Professor, Case Western Reserve University, Mathematics
http://www.case.edu/artsci/math/geuzaine