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DY: Dynamik und Statistische Physik

DY 34: Poster

DY 34.5: Poster

Montag, 7. März 2005, 15:30–18:00, Poster TU D

Lambert diffusion in three-dimensional porous media in the Knudsen regime — •Stephan Zschiegner^1,2, Stefanie Ruß¹, Armin Bunde¹ und Jörg Kärger² — ¹Institut für Theoretische Physik III, Justus-Liebig-Universität, Giessen — ²Institut für Experimentelle Physik I, Universität Leipzig, Leipzig

In general, diffusion of gas particles depends on the collisions between the gas molecules as well as on the collisions of the gas with the pore walls. Of particular interest for many real gases is the range of the so-called Knudsen regime, where the interaction of the molecules with the pore walls plays the crucial role and the intramolecular collisions can be neglected.

Here we present a new method to compute three-dimensional Knudsen diffusion in porous media. The trajectory of the diffusing particles is calculated using cube elements that assemble the porous system. The new algorithm is easy to implement in diffusion simulations and saves computation time due to its linear dependence on the system size.

For mimicking pores with different roughness, we consider the first four iterations of a generalized fractal Koch curve in three dimensions. For these model pores we have performed detailed investigations of self diffusion and transport diffusion. Our results show that both kinds of diffusion coefficients decrease with increasing surface roughness of the pores.