Indirect on-line determination of Newtonian fluid viscosity based on numerical flow simulations

Laboratoire de Biorhéologie et d'Hydrodynamique Physico-chimique, ESA CNRS 7057, 2 place Jussieu, Case 7056, 75251 Paris Cedex 05, France

Corresponding authors: carbache@ccr.jussieu.fr dantan@ccr.jussieu.fr pflaud@ccr.jussieu.fr

Received: 25 October 2001
Revised: 30 May 2002
Accepted: 23 August 2002
Published online: 29 November 2002

Abstract

A new indirect method of determining the viscosity of a Newtonian fluid flowing in a tube with a geometrical singularity is proposed. Due to this singularity, the shape of the dimensionless velocity profiles is closely correlated with the Reynolds number of the flow. Newtonian fluid flows were simulated numerically with various Reynolds numbers. Based on the results of these calculations, an abacus was plotted showing the relationship between the dimensionless velocity and the dimensionless viscosity. On the other hand, dimensionless velocities were also obtained by measuring velocity profiles on a hydrodynamic bench with an ultrasonic Doppler velocimeter. These experimental values were plotted on the abacus and the viscosity of the actual fluid was thus determined. Comparisons were made with viscometer measurements in order to assess the accuracy of the method and its range of validity. This method is of great potential interest for application to industrial plans when it is necessary to know the viscosity of a fluid undergoing a transformation without interrupting the process by taking fluid samples.