“…To ensure the confiability of results for this approach, the Boundary Element Method is used to compare and validated the results. The BEM has been successfully applied in the analysis of diffusion-advection equation in the last few years e. g. (Carrer, et al, 2017, Pettres, et al, 2015and Cunha, et al, 2013, as pure diffusion problems see Carrer, et al (2012), Ochiai, et al (2006 and Pettres, et al (2015). Numerical methods and theory of solutions of the problems for differential equations using FDM have been studied extensively by many researchers (Liu, Cheng, & Li Xiaoli, 2018), (Čiegis & Suboč, 2018) and so on.…”