caa a22 4500 465814239 CHVBK 20180323112123.0 cr unu---uuuuu 170327e19900701xx s 000 0 fre 10.1007/BF01339888 doi (NATIONALLICENCE)springer-10.1007/BF01339888 Etude du régime de mise en mouvement dans un viscosimètre de Couette à cylindres coaxiaux [Elektronische Daten] [R. Kouitat, G. Maurice, M. Lucius] The use of the Couette viscometer with coaxial cylinders for the evaluation of rheological properties and the establishment of behaviour laws of fluids, generally requires the knowledge of the shear rate at each instant and at any point in the gap. This quantity, which is generally unknown, can be approximated by simple mathematical expressions which are satisfactory for the applied torque flow but become less accurate as one moves away from the stationary state for the imposed speed flow. Most of the commonly used approximations are obtained under the assumption that the inertia of the fluid does not affect the flow and that the gap is small. In this work, we study the limit of the validity of certain approximations for the shear rate in an imposed speed transient flow on the example of a fluid of the Maxwell type. It is shown that the range of validity of these approximations depends on the viscosity and the density of the fluid, on the gap of the viscometer, and finally on a characteristic time representing the period under which an external perturbation is imposed to the fluid. The influence of these different parameters is expressed through a dimensionless number (Re) having the form of a Reynolds number. Steinkopff, 1990 C ouette viscometer nationallicence s tart-up motion nationallicence i mposed-speed nationallicence i nertia nationallicence M axwell f luid nationallicence Kouitat R. Laboratoire d'Energétique et de Mécanique Théorique et Appliquée, 2, rue de la Citadelle, 54000, Nancy, France aut Maurice G. Laboratoire d'Energétique et de Mécanique Théorique et Appliquée, 2, rue de la Citadelle, 54000, Nancy, France aut Lucius M. Laboratoire d'Energétique et de Mécanique Théorique et Appliquée, 2, rue de la Citadelle, 54000, Nancy, France aut Rheologica Acta Steinkopff-Verlag 29/4(1990-07-01), 332-341 0035-4511 29:4<332 1990 29 397 https://doi.org/10.1007/BF01339888 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF01339888 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Kouitat R. Laboratoire d'Energétique et de Mécanique Théorique et Appliquée, 2, rue de la Citadelle, 54000, Nancy, France aut NATIONALLICENCE 700 1- Maurice G. Laboratoire d'Energétique et de Mécanique Théorique et Appliquée, 2, rue de la Citadelle, 54000, Nancy, France aut NATIONALLICENCE 700 1- Lucius M. Laboratoire d'Energétique et de Mécanique Théorique et Appliquée, 2, rue de la Citadelle, 54000, Nancy, France aut NATIONALLICENCE 773 0- Rheologica Acta Steinkopff-Verlag 29/4(1990-07-01), 332-341 0035-4511 29:4<332 1990 29 397 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer