STEADY CONVECTION IN A HORIZONTAL FLUID LAYER

Steady Rayleigh-Bénard-convection in a rectangular box which is heated from below and cooled from above has been investigated. The onset of convection was calculated using linear Boussinesq equations and a Galerkin method. These calculations have demonstrated the stabilising effect of vertical boundaries. A special differential interferometer served to visualize the flow configurations in gases as well as in silicone oil. The density profiles were measured by means of a laser-differential interferometer with a moving mirror, evaluated quantitatively and compared with previously published results. The test fluids silicone oil (Pr=1780) and nitrogen (Pr=0.71) were chosen to demonstrate the influence of the Pr number both on the onset of convection and on the steady flow pattern at large Ra numbers. © 1979 Springer-Verlag.