Various aspects of nonlinear phenomena will be studied by controlled experiments. The first will address the problem of turbulence, in gas and liquid helium, in a Rayleigh Benard experiment of large physical size. A study of the transitions from chaos to weak turbulence and then to develop turbulence is planned. The second will study the dynamics of interfaces between various states of liquid crystals, smecticA-smecticC, smectic A-isotropic phases. The effects of crystal symmetries on the dendritic shapes will be studied. The third will be a continuation from the preceeding grant. In R-B experiments on mercury the effects of noise and or a third frequency on the transition to chaos in quasiperiodicity will be observed. Finally, in fluid-fluid interfaces of the Saffman-Taylor types, a number of puzzling questions remain on the selection and stability of fronts and bubbles.
