Portal de Periódicos da CAPES

Transition from laminar to turbulent drag in flow due to a vibrating quartz fork

2007; American Physical Society; Volume: 75; Issue: 2 Linguagem: Inglês

10.1103/physreve.75.025302

1550-2376

Michaela Blažková, D. Schmoranzer, L. Skrbek,

Fluid Dynamics and Vibration Analysis

Flow due to a commercially available vibrating quartz fork is studied in gaseous helium, He I and He II, over a wide range of temperatures and pressures. On increasing the driving force applied to the fork, the drag changes in character from laminar (characterized by a linear drive vs velocity dependence) to turbulent (characterized by a quadratic drive vs velocity dependence). We characterize this transition by a critical Reynolds number Recrdelta=Ucrdelta/nu, where Ucr is the critical velocity, nu stands for the kinematic viscosity, delta=sqrt[2nu/omega] is the viscous penetration depth, and omega is the angular frequency of oscillations. We have experimentally verified that the corresponding scaling Ucr proportional, sqrt[nuomega] holds in a classical viscous fluid over two decades of nu.