Heat transport and critical slowing down near the Rayleigh-Benard instability in cylindrical containers

Measurements of heat transport across layers of liquid He I heated from below show a sharp transition to fluid flow at the gravitationally driven Rayleigh-Bernard instability. The effective thermal conductivity of the convecting fluid is found to be a linear function of the reduced Rayleigh number (R-Rsub(c))/Rsub(c) and to have a slope which agrees with calculations. Critical slowing down near Rsub(c) is measured and found to be in excellent agreement with theory.(Auth.)