AN EXPERIMENTAL DETERMINATION OF THE TRANSITION TO TURBULENCE USING THE ELECTRIC DOUBLE LAYER.
Final scientific rept.,
FLORIDA UNIV GAINESVILLE ENGINEERING AND INDUSTRIAL EXPERIMENT STATION
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The research work done on this grant consists of developing an electrical method for the detection of the transition from laminar to turbulent flow in fluids and the application of this technique to several flow systems. The method depends on the existence of an electric double layer at the interface between a solid surface and an electrolyte. When the electrolyte is caused to flow in a glass tube a potential, streaming potential, will be developed between the ends of the tube. By monitoring this potential it is possible to ascertain the transition Reynolds number. This was done for both a straight and a curved circular pipe. In the case of the straight pipe the minimum critical Reynolds number was found to be 1907 plus or minus 3 and in a pipe with a radius of curvature of 55.9 inches the transition Reynolds number was found to be 3910 plus or minus 10. By varying the concentration of the electrolyte it is possible to vary the thickness of the electric double layer and therefore the region of the flow that is being examined. A study of this type, with double layer thickness varied from several thousand A to several hundred A, was done. It was found that the transition Reynolds number was increased by an increase in the double layer thickness. Author
- Fluid Mechanics