Quantum turbulence: The drag coefficient under oscillations of the quartz tuning fork immersed in He II

The experimental data on the motion of He II ex-cited by an oscillating quartz tuning fork immersed in helium are analyzed. It is shown that before attaining certain threshold values by a parameter, with the struc-ture of the Reynolds number, the normal and super-fluid components move independently. In this case the force and the drag coefficient are completely deter-mined by the motion of the normal component. When the parameter exceeds the threshold value which is critical for velocity the turbulent flow regime begins to work. This regime at a temperature below that for the transition to a superfluid state is attributed to the for-mation of quantized vortices. The universality of mo-tion of liquid helium at a temperature above the transi-tion point is discussed.