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nbulleid February 21, 2011 08:50

Transient flow solver
Hi all, got an annoying problem here. I started looking into CFD because I want to model particles in a low pressure flow. After doing some research I've found that the Knudsen number of the flow is somewhere between 1 and 10, which is a difficult area to solve. Does anyone know of any programs or methods that can solve in this regime?


christian_gross March 1, 2011 10:34

I'm currently investigating in the same field. So although I'm looking for answers myself, I can give you a short list of methods and implementations that look at least promising:

  • Particle methods: based on the kinetic theory with reduced number of particles
    • Discrete-Element-Method: see link for implementations; LAMMPS has a direct simulation monte carlo for low-density gases module
    • Corpuscular Method: LS-DYNA (mainly used for airbag inflation; a few publications available if you google for it (esp. by Lars Olovsson)
  • Lattice Boltzmann Methods: see link for implementations; reported problematic for high mach numbers

Hope that helps.

nbulleid March 1, 2011 11:03

Thanks for the reply Christian. I also found this paper which outlines some method for studying rarefied gas flow,

I'm currently using Star-CCM+ to study the particles in the continuum regime. This should help me find the best way to continue with my problem.

christian_gross March 2, 2011 06:58

Thanks for the link to the paper. Since I want to study the gas flow through apertures it is very helpful.

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