Besides the usually obtained transitions to steady or oscillatory states of flow, bifurcations in the solution spaces of extended fluid layers may also lead to chaotic states of motion which can be analyzed in simple cases in the form of phase turbulence. This term indicates that in contrast to fully evolved turbulence there does not exist a broad wavenumber spectrum of excited modes. Instead a fluctuating phase is responsible for the chaotic structures.
Heteroclinic orbits play an important role in the origin of phase turbulence.
This topic is investigated in collaboration with W.Pesch for centrifugally driven convection in a cylindrical annulus and for convection in an inclined layer heated from below. The latter topic is closely related to the problem investigated by E.Crespo in Madrid. M.Rubio in Madrid is planning to do an experimental study of inclined layer convection. Through the incorporation of additional constraints derived from the basic equations the bounds can be improved. These possibilities are investigated presently in collaboration with Dr.