Appendix 4: Time-Scale Separation Method
A4.1 DESCRIPTION OF THE TIME-SCALE SEPARATION METHOD
The problem of solving the diffusion equation when a concentration-dependent term appears at the second member is very difficult and it is the subject of a deep mathematical analysis because of the great number of applications.
A very wide and detailed review of analytical and semi-analytical methods designed to face this problem is reported in [1], while an analysis of this problem in the framework of a general analysis of diffusion problems is reported in the classic work [2].
However, a general analytical method of solution to this problem does not exist and a simulation algorithm has to be used [3,4].
Here, we want to introduce an approximate solution ...