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Tutorial: Multi-Species Lattice Boltzmann Models and Applications

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Kinetic theory of rarefied gas mixtures<br />

Full <strong>Boltzmann</strong> equations<br />

Indifferentiability Principle <strong>and</strong> H–theorem<br />

Indifferentiability Principle: when all the masses m σ <strong>and</strong><br />

cross-sections K σς are identical, the total distribution f = ∑ σ f σ<br />

obeys the single species <strong>Boltzmann</strong> equation.<br />

H–theorem: in the case of a mixture, the entropy inequality<br />

(H–theorem) is<br />

∑<br />

∫<br />

Q σ log(f σ )dξ ≤ 0. (6)<br />

σ<br />

R 3 ξ<br />

These properties of the full <strong>Boltzmann</strong> equations for mixtures will<br />

guide the design of BGK–type simplified models <strong>and</strong> consequently<br />

of the <strong>Lattice</strong> <strong>Boltzmann</strong> solvers.<br />

Pietro Asinari, PhD (Politecnico di Torino) <strong>Multi</strong>-<strong>Species</strong> LB <strong>Models</strong> Rome, Italy, on July 5-9, 2010 7 / 51

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