Heat Transfer. 2020;1–18. wileyonlinelibrary.com/journal/htj © 2020 Wiley Periodicals, Inc. | 1 Received: 20 February 2020 | Accepted: 22 March 2020 DOI: 10.1002/htj.21748 ORIGINAL ARTICLE Mechanism of Soret‐Dufour, magnetohydrodynamics, heat and mass transfer flow with buoyancy force, and viscous dissipation effects Lukman O. Ahmed 1 | Bidemi O. Falodun 2 | Jimoh Abdulwaheed 3 1 Department of Mathematical Science, Baze University, Abuja, Nigeria 2 Department of Mathematics, University of Ilorin, Ilorin, Kwara, Nigeria 3 Nigerian Communications Satellite Limited, Abuja, Nigeria Correspondence Bidemi O. Falodun, Department of Mathematics, University of Ilorin, Ilorin, Kwara +2348160637399, Nigeria. Email: falodunbidemi2014@gmail.com Abstract This paper examined the mechanism of both positive and negative effects of Soret‐Dufour with heat and mass transfer processes over an accelerating perme- able surface. The partial differential flow equations were simplified using similarity variables, and the resulting equations were solved numerically using the spectral homotopy analysis method (SHAM). The SHAM is used in separating nonlinear equations into linear and nonlinear. The physics of each pertinent flow parameters was used to examine their influence on velocity, temperature, and concentration fields. The effect of Soret‐Dufour was examined separately, and its negative effect was used to determine its in- fluence on velocity, temperature, and concentration fields. The result revealed that positive Soret‐Dufour enhances the boundary layer, whereas negative Soret‐ Dufour parameter decreases the boundary layer. The result presented in this paper is in good agreement with existing works in literature. KEYWORDS heat transfer, mass transfer, negative and positive Soret‐Dufour, spectral homotopy analysis method, thermal radiation