Abstract
Double diffusion is one of the important topics due to its varied applicability across many disciplines of science and engineering. The diffusion of heat as well as mass is a phenomenon which is governed by 3 mutually coupled equations. The Dufour effect is an effect where the heat transfer is affected due to existence of concentration gradient. The current work shows the combined influence of two separate phenomenon i.e. viscous dissipation and the Dufour effect in a square porous annulus. Finite element method is used as solution tool to solve the governing partial differential equations. A computer programme is developed to deal with matrix form of equations arising due to application of FEM. It is observed that the energy content of the medium levates with increase in viscous dissipation and Dufour effect. The isotherms towards the inner wall of porous annulus become smoother due to increased Dufour coefficient.