Table of Contents

• Abstract
  
  
• Introduction
  
  
• Convection in Rotating Frames
  
  
• The Experiment
  
  
• Results
  
  
• Conclusions
  
  
• Acknowledgements
  
  
• References
  
  

Abstract

A hydrodynamic flow visualization experiment was performed in water to investigate how an expanding pulsed jet rotates when injected off-axis into a rotating annular flow field. In the experiment the pulsed jets were injected parallel to, but radially displaced from the axis of rotation. The jets were observed to counter-rotate ΔΦ ~ π/2 to π radians relative to the rotating frame before dispersing into the background flow because of turbulence. The counter-rotation of the jet is produced by the change in moment of inertia with conserved angular momentum, or equivalently, the partial conservation of circulation due to radial divergence of the flow at the head of the jet. Rapid turbulent entrainment of the pulsed jet flow with the background flow during radial divergence limits the net rotation of the jet, whereas shear within a differentially-rotating background flow enhances the net rotation of the jet. The Reynolds number of the experiment was ≅ 10⁵ in order to simulate the behavior of turbulent entrainment at high Reynolds number. The differential rotation of the background flow was varied from constant rotation, dΩ/dR = 0,to Ω ∝ 1/R. The flow was visualized by pulsed hydrogen electrolysis from a tungsten wire and dispersed guanidine in water. The flow was imaged using a digital video camcorder operating at 30 Hz frame rate. This hydrodynamic flow visualization experiment is a precursor to the design and development of an α - Ω dynamo experiment using liquid sodium.