Throughflow on thermosolutal convection in fluid–porous systems with relevance to tissue engineering scaffolds

Abstract

This theoretical study investigates the effects of throughflow on the onset of double-diffusive (thermosolutal) convection within a two-layer system comprising a free fluid region overlying a porous medium, both saturated with a binary fluid mixture. The system is examined under thermally insulating boundary conditions, and the coupled governing equations are derived using the Boussinesq approximation. A linear stability analysis is performed via the normal mode method, and the critical conditions for the onset of convection are obtained using a regular perturbation technique. The analysis reveals that an aiding (cooperative) buoyancy force reduces the critical Rayleigh number, enhancing the onset of convection, while an opposing force suppresses convective activity. Upward throughflows exert a stabilizing effect on the system, whereas downward throughflows lead to destabilization. It is also observed that lower Darcy numbers, indicative of reduced permeability in the porous layer, inhibit convective motion, while higher Lewis numbers promote it due to enhanced solutal diffusivity. These results offer fundamental insights into transport phenomena in porous media and can inform the design and optimization of tissue engineering scaffolds, where fluid and nutrient transport through porous biomaterials is critical for cell viability and function. The findings underline the importance of flow configuration, scaffold permeability, and diffusive properties in governing mass and heat transport in biomedical systems. Graphical representations of vertical velocity distributions and stability boundaries further elucidate the interaction of physical parameters influencing the convective regime. © 2025 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.