Experimental measurements of non-Newtonian fluid flow through a stenotic tube

Abstract

This paper presents an experimental study of the laminar flow of a non-Newtonian fluid through 75% (by area reduction) stenotic tubes. The fluid behaviour was described by the Herschel Bulkey non-Newtonian model. The non-Newtonian fluids were aqueous solutions of 0.1% Carbopol 940. Upstream flow conditions were steady and spanned a range of generalized Reynolds numbers Reg from 0.20 to 13.66. The velocity profiles were measured with a Laser Doppler Anemometry (LDA). This study allows us to see locally the influence of the geometry and the non-Newtonian character of the fluid on the velocity profiles, the pressure drops and flow resistance. From the experimental data, the frictional resistance decreases with increasing generalized Reynolds number Reg and resistance gave a weak value in a stenotic tube as compared to the flow in a simple tube. At the level of stenosis, a correlation relating of the Euler number to the generalized Reynolds number is developed. To compare the upstream and downstream parts of the stenosis, it is preferable to represent the pressure drops by the friction factor f. This factor f in upstream and downstream decreases linearly with the generalized Reynolds number Reg.