The Form of Waiting Time Distributions of Continuous Time Random Walk in Dead-End Pores

الملخص EN

Anomalous dispersion of solute in porous media can be explained by the power-law distribution of waiting time of solute particles.

In this paper, we simulate the diffusion of nonreactive tracer in dead-end pores to explore the waiting time distributions.

The distributions of waiting time in different dead-end pores show similar power-law decline at early time and transit to an exponential decline in the end.

The transition time between these two decline modes increases with the lengths of dead-end pores.

It is well known that power-law distributions of waiting time may lead to anomalous (non-Fickian) dispersion.

Therefore, anomalous dispersion is highly dependent on the sizes of immobile zones.

According to the power-law decline, we can directly get the power index from the structure of dead-end pores, which can be used to judge the anomalous degree of solute transport in advance.