Experimental quantification of oscillating flow in finite-length straight elastic vessels for Newtonian and non-Newtonian fluids

Abstract To better understand the complex flow in arteries it is necessary to analyze the fluid–structure interaction between the time dependent velocity field, the non-Newtonian fluid, and the elastic blood vessels and to investigate the wall-shear stress distribution that develops in the elastic vessel during an oscillation cycle. The scope of this study is to quantify the influence of the viscoelastic fluid properties on the fluid–structure interaction and the wall-shear stress of a straight elastic vessel by analyzing oscillatory flow of both a Newtonian reference fluid and a non-Newtonian fluid. Unlike in Womersley’s analyses, an elastic vessel of finite length with a non-Newtonian fluid is investigated in this study. Furthermore, quantitative benchmark data for numerical fluid–structure interaction methods are provided. Time-resolved particle-image velocimetry, static pressure measurements, and wall detection are used to measure the velocity field, the pressure distribution, and the vessel dilatation with high temporal and spatial resolution. The mechanical properties of the vessel material are determined by a dynamic mechanical analysis and the viscosities of the Newtonian and the non-Newtonian fluid are measured by a rheometer. The fluid–structure interaction is measured for a sinusoidal oscillating flow in a Reynolds number range 472 ≤ R e N F ≤ 971 and 503 ≤ R e N N F ≤ 1065 for the Newtonian reference fluid and the non-Newtonian fluid. The Womersley number range is 5 . 97 ≤ W o N F ≤ 8 . 53 for the Newtonian reference fluid and 6 . 14 ≤ W o N N F ≤ 8 . 79 for the non-Newtonian fluid. The results show that the wall-shear stress maximum increases up to 32%–38% for the non-Newtonian fluid despite a 10%–45% higher wall-shear rate for the Newtonian reference fluid. Furthermore, the amplitudes of the dilatation and the pressure in the vessel are more pronounced for the non-Newtonian fluid.