Soret effect on stability of Darcy problem in a bidispersive porous medium with an exothermic chemical surface reaction

Abstract We examine a saturated bidispersive porous medium undergoing an exothermic chemical reaction at its lower boundary. The fluid flow within this medium is modelled using the Darcy approach. While the Dufour effect is disregarded, the influence of the Soret effect is thoroughly explored. This problem represents a complex multiphysical phenomenon that integrates fluid dynamics, heat and mass transfer, chemical kinetics and thermoelectric effects. This problem finds relevance in various scientific and engineering applications, including enhanced oil recovery, chemical engineering, environmental engineering and energy systems. We introduce a complementary energy theory alongside a linear theoretical framework for the model. The Chebyshev collocation method is employed to derive both linear and nonlinear results. Our findings reveal that the effect of enhancing the Soret coefficient on the system's stability is contingent upon the boundary conditions and the Lewis number. Specifically, an increase in the Soret coefficient generally stabilises the system during stationary convection. Conversely, in scenarios where oscillatory convection prevails, a higher Soret coefficient tends to destabilise the system.