“…The time derivative term */*t will in this case be dealt with by means of a step-by-step integration process, with approximation of the time derivative by means of finite differences, and the resulting terms corresponding to previous instants will be considered as being pseudo-forces in the second member, approximated by means of the DRM. This third option is taken by various authors [5,6,9,[12][13][14][15], and this is the one taken up in the present study. In what follows, the differential operator associated with the convection-diffusion equation will be…”