Transition to Turbulence for a Quartz Tuning Fork in Superfluid 4He
Transition to Turbulence for a Quartz Tuning Fork in Superfluid 4He
复制标题
超流体 4He 中石英音叉向湍流的转变
DOI：
10.1007/s10909-009-9901-3
复制
发表时间：
2009
影响因子：
2
通讯作者：
Bradley D
中科院分区：
文献类型：
--
作者：
Bradley D
我们已经研究了一个商业石英音叉浸没在超流4 He的共振，在5 mK和1 K之间的温度，并在零和25巴之间的压力。音叉的力-速度曲线在低速时显示线性阻尼力。随着速度的增加，我们看到了与超流体中量子化涡线引起的额外阻力的出现相对应的转变。我们粗略地称这种额外的贡献为“湍流阻力”。湍流阻力，减去线性阻尼力后得到的，是独立的压力和温度低于1 K，很容易拟合的经验公式。从线性阻尼（层流）的转变发生在一个明确定义的临界速度，该速度对于我们测量的压力和温度具有相同的值。后来的实验使用相同的叉子在一个新的细胞揭示了不同的行为，与速度步进不连续的过渡，有点类似于以前的观察振动线谐振器和振荡球。我们比较和对比所观察到的行为的超流阻力和惯性力与测得的振动线。
We have studied the resonance of a commercial quartz tuning fork immersed in superfluid4He, at temperatures between 5 mK and 1 K, and at pressures between zero and 25 bar. The force-velocity curves for the tuning fork show a linear damping force at low velocities. On increasing velocity we see a transition corresponding to the appearance of extra drag due to quantized vortex lines in the superfluid. We loosely call this extra contribution “turbulent drag”. The turbulent drag force, obtained after subtracting a linear damping force, is independent of pressure and temperature below 1 K, and is easily fitted by an empirical formula. The transition from linear damping (laminar flow) occurs at a well-defined critical velocity that has the same value for the pressures and temperatures that we have measured. Later experiments using the same fork in a new cell revealed different behaviour, with the velocity stepping discontinuously at the transition, somewhat similar to previous observations on vibrating wire resonators and oscillating spheres. We compare and contrast the observed behaviour of the superfluid drag and inertial forces with that measured for vibrating wires.