[vtkusers] Streamlines vs. Lagrangian drifters

[christopher moore]

Hi Avan & other users,

I don't have any technical advice for your tcl problem, but I wanted to
make a point that I'm sure you know (but others might not). "Animating" a
streamline is not quite the same as what most folks call a tracing a
particle path, or the path a drifting particle might take in a fluid-flow
problem.  If the velocity field is "steady" it is not a problem, but a
velocity field that changes with time will cause a tracer (or particle, or
drifter) to trace out a path different than the streamline traces at the
same initial position.

Those of us who do oceanography or fluid dynamics might benefit from a
class like vtkStreamer that, instead of rendering streamlines, animates
the path of a drifting particle.  Perhaps someone has done this already
that might help us out?  I was hoping for something with an accurate
time-stepping scheme - perhaps a Runge-Kutta (as opposed to simple
forward-euler)?  I'm a hack of a developer, but if nobody else has done
this I'll give it a try.  You'll have to promise not to laugh at my code,
though....

Yours,
______________________________________________________________
Christopher Moore                             tel 206.526.6779
Research Scientist, Oceanography              fax 206.526.6744
University of Washington/JISAO/NOAA-PMEL
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> Date: Thu, 07 Dec 2000 11:09:27 +0100
> From: Avan Suinesiaputra <avan at science.uva.nl>
> To: Berk Geveci <berk.geveci at kitware.com>, vtkusers at public.kitware.com
> Subject: Re: [vtkusers] Accessing streamer array in vtkStreamer
> 
> 
> I want to make a tracer particle animation over a streamline.
> First I put spheres in my streamline's start positions.
> Then I animate the spheres using a vtkStreamArray's object to track
> position of each sphere in a specified time.
> Do you know a method to do that without vtkStreamArray.
> I created the processing in C++ and it works good.
> 
> Avan
> 
> Berk Geveci wrote:
> 
> >         Those two methods are excluded from tcl wrapping because there
> >         is no tcl equivalent of vtkStreamArray in tcl (vtkStreamArray
> >         is an ordinary C++ class, it does not inherit from vtkObject).
> >         Why do you want to access the stream array from tcl ?
> >