Effect of the days scrolling on the natural convection in an open ended storage silo

The problem of unsteady natural convection heat transfer in a vertical, open ended, porous cylinder heated laterally with a sinusoidal time variation of the temperature has been investigated numerically. The model considered is the classical Darcian flow coupled with the energy equation. In the case of constant wall temperature, two types of chimney flows take place, with and without fluid recirculation. The present problem depends on the filtration Rayleigh number (Ra), the aspect ratio (A) and the inlet-outlet conditions (Bi). For low dimensionless temperature amplitudes (XA < 0.5) in the sinusoidal time variation, the resulting heat transfer is found to be globally equivalent to the case of constant wall temperature. The observed relative difference between sinusoidal and constant wall temperature is less than 5%. This difference decreases as the Ra is reduced.