[Paraview] File Format for Particles

[Ivo Roghair]

Hi Shi,

Saving such amounts of data in ascii format is not going to be 
efficient. We just accepted this fact, otherwise we should go to binary 
formats.

In our group we have discrete particle simulations, and we export vtk 
files (xml format -- an unstructured grid to be precise) that contains 
all the particle data. I have included an example of such a file below. 
You write the point positions of the particles first, followed by data 
concerning the movement of the particle, the diameter and other stuff 
like rotation, temperature, etc... I don't see what you mean by 
redundant data. When you load this file into Paraview choose the glyph 
option, choose 'sphere', set 'radius' to 1 (it is initially set to 0.5), 
scale mode to 'scalar' and scale factor to 1. You can then draw the 
particles. You can color them by velocity, temperature, rotation or 
whatever you included in the file, or you can choose to show arrows 
(another glyph) to display the particle movement.
For the flow field, which is calculated on a structured grid, you can 
use another file format, e.g. rectilinear grid. In all cases the 
kitware/vtk file formats documentation is going to be useful.

Regards,
Ivo Roghair

PhD student at Fundamentals of Chemical Reaction Engineering
University of Twente, The Netherlands

------------------ BEGIN EXAMPLE FILE ---------------------
<VTKFile type="UnstructuredGrid" version="0.1" byte_order="LittleEndian">
  <UnstructuredGrid>
    <Piece NumberOfPoints="3" NumberOfCells="0">
      <Points>
        <DataArray name="Position" type="Float32" NumberOfComponents="3" 
format="ascii">
        0 0 0 1 1 1 0 0 1
        </DataArray>
      </Points>
      <PointData  Vectors="vector">
        <DataArray type="Float32" Name="Velocity" NumberOfComponents="3" 
format="ascii">
        4 4 4 4 0 0 2 2 -2
        </DataArray>
    <DataArray type="Float32" Name="Diameter" format="ascii">
        0.1 0.5 1
        </DataArray>
    <DataArray type="Float32" Name="Temperature" format="ascii">
        273 300 350
        </DataArray>
      </PointData>
      <Cells>
        <DataArray type="Int32" Name="connectivity" format="ascii">
        </DataArray>
        <DataArray type="Int32" Name="offsets" format="ascii">
        </DataArray>
        <DataArray type="UInt8" Name="types" format="ascii">
        </DataArray>
      </Cells>
    </Piece>
  </UnstructuredGrid>
</VTKFile>
---------- END EXAMPLE FILE --------------

Shi Jin wrote:
> Hi there,
>
> I am doing a simulation of fluid-particle interactions, in which I generate a lot of data for particles. I am looking for the efficient file format to store my particle information for visualization with paraview. For example, is there a file format that allows me to store all the particle information at a given time in a single ascii file, which looks like
> #1-id 2-radius 3-rho_p 4-fixed 5-x 6-y 7-z 8-u 9-v 10-z 11-w1 12-w2 13-w3 14-alpha 15-theta 17-phi
> 0 0.500000 1.200000 0 2.077176 2.678227 8.649375 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000
> 1 0.500000 0.800 0 2.728281 0.873571 6.806029 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000
> ...
>
> I guess for the purpuse of visualization, we need radius, rho_p(for color), x,y and z at least. The rotation information would be nice to have but is considered optional at this stage. 
>
> I am thinking to save different time results in different files to make the loading efficient in terms of memory since I have a lot of particles here. Then we can produce animation using time control. I guess we could use VTK formats but that has lots of redundant information.
>
> I saw some very early discussion on a similar topic in the forum but didn't get the conclusive answer. I would appreciate some advice for the current version of paraview.
>
> Thank you very much.
>
>  --
> Shi Jin, PhD
>
>
>
>       
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