Abstract:
In the present paper the formation of Liesegang structures, i.e. the process of periodic
deposition with the mutual diffusion of two reacting chemicals in the presence of an external
constant electric field, is studied using numerical modeling. The mathematical model of the
process consists of three differential equations of diffusion-reaction for the concentrations of the
initial components and the resulting precipitate. The kinetics of sedimentation is described in
accordance with the Ostwald’s supersaturation theory. The equations of the mathematical model
in one-dimensional and two-dimensional statements were solved numerically using the control
volume method using computer code written by the authors in the C ++ language. As a result of
numerical simulation in the absence of an electric field, periodic structures were obtained formed
of the precipitate, which qualitatively corresponds to the patterns observed in the experiments.
It is shown that numerically obtained Liesegang rings satisfy the well-known laws: the ratio of
the distances to neighbouring rings remains constant and there is a power dependence between
the distances to the rings and the time of their formation. The influence of the ratio of the
concentration of the starting substances and the electric field strength on the nature of the
structures formed is investigated. It also has been shown that an increase in the electric field
strength leads to an increase in the number of structures formed.
