Statistical method to evaluate the critical Reynolds number for pseudoplastic fluids in tubes
1994
Campos, D.T. | Steffe, J.F. | Ofoli, R.Y.
An experimental, non-intrusive tube system with appropriate instrumentation for measuring pressure drop and mass flow rate was developed to investigate the departure from laminar flow of pseudoplastic fluids (aqueous solutions of sodium carboxymethylcellulose). A critical Reynolds number was selected to correspond to the intersection of the two lines joining the laminar and turbulent flow date on the pressure drop versus Reynolds number plots. The standard deviation of pressure drop increased at these critical points. Results also indicated large spikes at these points in the plots of variance ratio of pressure drop versus the critical Reynolds number. This phenomenon could form the statistical basis for establishing the departure from laminar flow. In the laminar region, standard deviations were low, suggesting calm, stable flow of the fluids, a well known characteristic of laminar flow.
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