ABSTRACT
It has been recently proposed a time and space state continuous approach to the evolution of depth of a pit corrosion based on a Fokker-Planck (FP) equation. This approach is more realistic than to consider discrete markovian chain, since the evolution of corrosion in time and space is a continuous stochastic process. However, a FP approach is an approximation to the general expansion of master equation known as the Kramers-Moyal (KM) expansion. Besides that, the FP approach presented previously considered only the particular case in which the drift and the diffusion terms are time independent. The goal in this present paper is two-fold. The first one is to grasp the underlying stochastic dynamic of corrosion fluctuations in order to unveil the driving mechanisms within a unified framework. The second one is to determine from the stochastic equations that emerge from the first step, the family of Probability Density Functions (PDFs).
