Article révisé par les pairs
Résumé : Convection in viscoelastic fluids may be induced by oscillatory or stationary instabilities. When the oscillatory instability appears first, the system may be described, in its vicinity by coupled Ginzburg-Landau equations. We study the convective and absolute instabilities of the steady states of these equations. We analyze pattern selection and stability in deterministic and stochastic systems and discuss the possibility of noise-induced phase transitions.