Effect of wall compliance on vessel hemodynamics: A baseline particle tracking velocimetry study

Fluid–structure interaction (FSI) is integral to cardiovascular biomechanics, highlighting the dynamic relationship between blood flow and vessel walls. Understanding FSI is essential for accurate vascular behavior models, influencing parameters such as wall shear stress (WSS), flow patterns, and vessel deformation. Vessel compliance, a key parameter in FSI, is critical as changes in arterial stiffness are linked to diseases like atherosclerosis and hypertension. Clinically, arterial compliance is assessed via pulse wave velocity (PWV). However, a specific quantitative relationship between PWV and compliance, from a fundamental fluid dynamics perspective, has not been established. In this work, we address this gap as well as explore the specific effects of compliance on hemodynamic parameters including velocity and pressure fields as well as WSS. We manufactured three idealized compliant tubes with varying wall thicknesses to vary their compliance and used volumetric particle track velocimetry to measure each tube's velocity fields at three inflow flow rate magnitudes. We observed that increased vessel compliance lowered the average pressure in the tube, but did not affect the peak acceleration pressure. Additionally, increased compliance caused more chaotic and non-uniform velocity and WSS trends. Finally, our study introduces a novel perspective for quantitatively relating PWV and compliance. Overall, our results provide a general experimental reference for FSI in vessels.