Remarkable differences in dispersion of a tracer material injected into turbulent pipe flows of water and water containing as little as 2·5 parts per million by weight of a soluble high-molecular-weight drag-reducing polyoxyethylene additive have been measured. Analysis of the tracer response curves in terms of a simple one-parameter model shows that the observed results are compatible with a drag-reduction mechanism based on thickening of the viscous sublayer adjoining the wall. Other experiments, reported briefly, suggest that polymer adsorption on to the wall is responsible for this thickening.
A nondisturbing photochromic dye trace, technique has been employed t o study the flow profiles of water-alcohol solutions containing the drag reducing polymer Polyox at concentrations ,
1967.(AB) Rxndborn.
A simple device out of a broken buret has been developed for the determination of the sphericity factor of irregular particles. The working of the device is based on the unsteady laminar flow of liquid through the bed of solid particles. The Kozeney-Carmen equation is employed to obtain the sphericity factor.
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