Double-diffusive convection in a magnetic nanofluid-filled porous medium: Development and application of a nonorthogonal lattice Boltzmann model

In this work, to fill the rare reports on double-diffusive convection (DDC) considering the effects of porous medium, nanofluid, and magnetic field at the same time, we first developed a full nonorthogonal multiple-relaxation-time lattice Boltzmann (LB) model for DDC in a nanofluid-filled porous medium subjected to a magnetic field. The capability of the newly proposed model is then verified. By solving specific problems via the full model with specific control parameters, we show that the nonorthogonal LB model is accurate for handling the effects of the porous medium, nanofluid, and magnetic field. Finally, we apply the model to DDC in an Fe3O4-water nanofluid-filled porous cavity with a hot left boundary and examine the effects of magnetic field intensity and inclination angle on the flow, heat, and mass transfer inside the porous medium. Results show that heat and mass transfer can both be adjusted by varying the intensity and inclination angle of the magnetic field. When the external magnetic field is applied, the heat and mass transfer along the hot wall declines monotonously with increasing the strength of the magnetic field. In contrast, the average Nu and Sh increase at first and then decrease with the inclination angle of the magnetic field, reaching the maximum at around gamma = 45 degrees. Results in this work pave a tunable way for heat and mass transfer regulation inside a magnetic nanofluid-fill porous medium. In addition, this work provides essential reference solutions for further study on DDC in a nanofluid-filled porous medium subjected to a magnetic field. Published under an exclusive license by AIP Publishing.