Convegni ATI - Accesso riservato soci CTI

Autore: E. Cafaro, A. Saluzzi

Collana: CA - 50 - Saint Vincent 1995

Note:
Benard convection is a phenomenon in which hydrodinamic effects interact with thermodynamic effects. In this paper we introduce the concept of the entropy balance in Benard convection and explain the role of the entropy in the conditions for the onset of convection. The condition for the onset of conversion can be expressed in the form of the product of two terms: the ratio of rate of conversion of the potential energy due to buoyancy difference into kinetic energy to the rate of dissipation of the kinetic energy by viscous dissipation; the ratio of the entropy flux due to convection to the entropy production rate by thermal conduction. The entropy of the Benard cells comprises two temperature components: a temperature component which varies periodically in the space depending on the cellular structure and an aperiodic component. The periodic component reduces the entropy while the aperiodic component increase it. Overall, the presence of convection increases the entropy of the system.