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espressomd / espresso

The ESPResSo package
https://espressomd.org
GNU General Public License v3.0
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Inaccuracy in the lattice boltzmann tutorial #4804

Closed sH4MbLe5 closed 9 months ago

sH4MbLe5 commented 10 months ago

In espressomd/espresso/tree/python/doc/tutorials/lattice_boltzmann/lattice_boltzmann_sedimentation.ipynb the 'dist' parameter of the espressomd.shapes.Wall object should be set to spacing not to 1.

jngrad commented 10 months ago

Thank you for your feedback. As far as I remember, this spacing value was deliberately chosen such that the ceiling wall wouldn't exert a non-bonded force on the top layer of the particle cloud during the first time step. For the LB algorithm, the distance is actually rounded down, thus a distance of 1.0 or 1.22 will in either case create a LB boundary of thickness 1. The user guide doesn't seem to mention this rounding-down feature, though. I've opened a PR to add a paragraph to that effect (see 99f4275d:doc/sphinx/lb.rst).