Analysis of results

Results processing

HemeLB stores output data in a compressed *.dat file. To make this human-readable use the hemeXtract tool provided in the download files. There are multiple options for how files can be convertedbut the most straightforward is:

hemeXtract -X output.dat > readable-output.txt

Where output.dat is the address of the file you wish to convert and readable-output.txt is the file to which it is converted too.

The readable-output.txt file contains all the data from the simulation. To observe transient evolution of a model, or results at a specific step, it can be easier to split this into separate files for each output step. This can be achieved with the provided paraviewProcessing.sh script. This splits the readable-output.txt file into sequentially numbered paraview-file-name text files.

bash paraviewProcessing.sh readable-output.txt paraview-file-name

Whilst many visualisation softwares are available, this tutorial will use Paraview. This toolkit is one of the more widely used in the scientific fields.

Visualising results

  1. Import paraview-file-nameXX.txt files: File $\rightarrow$ Open $\rightarrow$ Navigate to folder $\rightarrow$ double-click on paraview-file-name..txt (type GROUP)

  2. Click green apply button on LHS

    After importing files

  3. Change default comma (,) in Field Delimeter Characters to a space ( )

  4. Click green apply button on LHS (this is a recurring theme in Paraview)

    Correcting for file format

  5. Filters $\rightarrow$ Alphabetical $\rightarrow$ Table To Points

  6. Change Y Columns to ‘gridY’ and Z columns to ‘gridZ’

  7. Click green apply button on LHS

    Converting to points

  8. Ensure RenderView panel is active and click on eye next to TableToPoints1 in Pipeline

  9. Change rendering option from ‘Solid Colour’ to ‘velZ’

  10. Use Play and rescale options to watch time evolution

    Evolution of inlet

This is just a basic introduction to Paraview. It is a powerful tool that can permit much more complex visualisation of data.

Velocity vector field throughout the bifurcation

End of tutorial

You have completed the first simulation tutorial for HemeLB.

Previous