Numerical and Experimental Investigation of a Non-Newtonian Flow in a Collapsed Elastic Tube

Abstract

Simulations are performed to investigate the flow of a shear-thinning, non-Newtonian fluid in a collapsed elastic tube and comparisons are made with experimental data. The fluid is modeled by means of the Bird- Carreau viscosity law. The computational domain of the deformed tube is constructed from data obtained via computer tomography imaging. Comparison of the computed velocity fields with the ultrasound Doppler velocity profile measurements show good agreement, as does the adjusted pressure drop along the tube’s axis. Analysis of the shear rates show that the shear-thinning effect of the fluid becomes relevant in the crosssections with the biggest deformation. In fact, the maximum shear rate is about a factor of thirty larger than its corresponding maximum value in the undeformed tube, and the viscosity is reduced by a factor of two. The effect of the shearthinning behavior has also been compared with identical simulations carried out for a Newtonian fluid.

Keywords

• computer simulation
• computer tomography
• collapsed elastic tube
• openfoamo®
• shear-thinning fluid
• ultrasound doppler velocimetry