Periodic mixed convection in horizontal porous layer heated from below by isoflux heater

Abstract EN

Numerical study for transient mixed convection in a two-dimensional horizontal porous layer heated from below by a constant heat flux source is carried out in the present paper.

The transient thermal field, flow field, and average Nusselt number are presented for a wide range of the Péclet number, Pe, for the particular case of Rayleigh number Ra = 102 and the ratio of heater length to the porous layer thickness A = 1, 3 and 5.

It is found that for A = 3 and A = 5 with small values of the Péclet number, the free convection mode is dominated, while for large values, of the Péclet number, the forced convection mode is dominated.

However, for moderate values the oscillatory mixed convection is observed and a periodic variation of the average Nusselt number is obtained.

When the heater length is equal to the porous layer thickness (A = 1) the steady-state results are obtained for the range of Pe = 0.1 – 10.