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Code accompanying The Lattice Boltzmann Method: Principles and Practice
http://lbmbook.com
MIT License
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Is it possible to extract physical parameters of a multiphase Shan-Chen simulation? (chapter 9) #6

Closed a-rostek closed 3 years ago

a-rostek commented 3 years ago

Hi,

is it possible to extract real physical values from a multiphase simulation which uses Shan-Chen forces? I've been trying to do this with code from chapter 9, but so far with no success.

Also, how does one set a value of G (Shan-Chen force attraction parameter) in a simulation? Is it just trial and error until your simulation matches experiment?

I tried extracting conversion factors between lattice units and physical ones by looking at kinematic viscosity, delta pressure (laplace pressure) and matching them to real substances (for example water). But the derived conversion factors give me ridiculous values when I try to calculate physical density and other quantities.

And now I am questioning whether it's possible at all, since I am not sure if that Shan-Chen parameter G or Shan-Chen equation of state represent anything real.

timmkrueger commented 3 years ago

The G parameter has no direct real-world meaning. It is an effective parameter describing the interaction of different fluids (or self-interaction of a single fluid). The usual approach is to change G and "measure" the resulting surface tensions via the Laplace test. The conceptual simplicity of the Shan-Chen model means that you cannot directly map the real world to the simulations and vice versa. There are some more recent papers where more realistic equations of state have been included in the Shan-Chen approach, though.

a-rostek commented 3 years ago

Thank you for answering. And thank you for writing this great book :)