On the action of internal heat sources on convective motion in a porous medium heated from below

The effect of internal heat sources on the flow pattern in the filtration convection problem with cosymmetry is studied numerically. Low-intensity heat sources, whose presence leads to violation of cosymmetry and breakdown of the one-parameter family of steady regimes are considered. Theoretically predicted scenarios for the breakdown of the family into a finite number of steady regimes and the occurrence of slow periodic motions are confirmed. The existence of relaxation oscillations is established for large Rayleigh numbers.