43 research outputs found
Numerical analysis of reversible A + B <-> C reaction-diffusion systems
We develop an effective numerical method of studying large-time properties of
reversible reaction-diffusion systems of type A + B C with initially
separated reactants. Using it we find that there are three types of asymptotic
reaction zones. In particular we show that the reaction rate can be locally
negative and concentrations of species A and B can be nonmonotonic functions of
the space coordinate x, locally significantly exceeding their initial values.Comment: To appear in EPJ B, 5 pages + 6 figure
How to Calculate Tortuosity Easily?
Tortuosity is one of the key parameters describing the geometry and transport
properties of porous media. It is defined either as an average elongation of
fluid paths or as a retardation factor that measures the resistance of a porous
medium to the flow. However, in contrast to a retardation factor, an average
fluid path elongation is difficult to compute numerically and, in general, is
not measurable directly in experiments. We review some recent achievements in
bridging the gap between the two formulations of tortuosity and discuss
possible method of numerical and an experimental measurements of the tortuosity
directly from the fluid velocity field.Comment: 6 pages, 8 figure