To investigate the validity of appending the Gorter-Mellink friction term to the equations of motion of liquid helium the temperature was measured along the axis of a channel carrying a supercritical heat current. A single thermometer on a traversing assembly was used permitting local measurements both in the interior of the channel and in the jet formed in the free fluid.
The temperature gradient in the interior of the channel is found to be in agreement with the Gorter-Mellink law up to the lamda point, but goes to zero within a channel diameter, in the free jet. Since the relative velocity between the two fluids is probably continuous along the axis of the jet in the vicinity of the exit, the disappearance of the temperature gradient appears to be inconsistent with the predictions of the Gorter-Mellink term.
The Gorter-Mellink A(T) was also measured up to the lamda point. A much stronger divergence is found as Tλ is approached than was indicated by previous measurements.
