Transient flow solver

nbulleid · February 21, 2011, 07:50

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?

Thanks

christian_gross · March 1, 2011, 09:34

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, 10:03

Thanks for the reply Christian. I also found this paper which outlines some method for studying rarefied gas flow, http://www.nist.gov/data/PDFfiles/jpcrd540.pdf.

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, 05:58

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

February 21, 2011, 07:50	Transient flow solver	#1
nbulleid New Member Join Date: Jan 2011 Posts: 3 Rep Power: 3	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? Thanks

March 1, 2011, 09:34		#2
christian_gross New Member Christian Gross Join Date: Oct 2009 Location: Germany Posts: 5 Rep Power: 4	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.

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March 1, 2011, 10:03		#3
nbulleid New Member Join Date: Jan 2011 Posts: 3 Rep Power: 3	Thanks for the reply Christian. I also found this paper which outlines some method for studying rarefied gas flow, http://www.nist.gov/data/PDFfiles/jpcrd540.pdf. 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.

March 2, 2011, 05:58		#4
christian_gross New Member Christian Gross Join Date: Oct 2009 Location: Germany Posts: 5 Rep Power: 4	Thanks for the link to the paper. Since I want to study the gas flow through apertures it is very helpful.