The influence of a fluid-porous interface on solar pond stability

The linear instability of the gradient zone of a solar pond containing a fluid-porous interface is investigated. It is found that the gradient zone can retain the same stability for lower values of the solute Rayleigh number with the introduction of a porous material compared with a purely fluid layer, whilst maintaining the same lower convective zone temperature.Interestingly, it is also shown that for certain parameter values the penetration of a porous medium into the gradient zone can cause the temperature of the lower convective zone to rise. However, for certain parameter ranges, when the fluid-porous interface is towards the top of the gradient zone, the solar pond can become highly unstable.

► The linear instability of a solar pond with a fluid-porous interface is explored.
► Compared to a purely fluid solar pond, the fluid-porous pond can be more stable.
► Porous media presence can cause the temperature of the lower convective zone to rise.
► Instabilities occur when the fluid-porous interface is in the upper gradient zone.