On the study of fluid flow through a compliant tube with internal obstructions.*

Atherosclerosis often leads to severe pathological conditions, making it critical to understand the fluid-structure interaction (FSI) as blood flows through compliant blood vessels. Despite extensive computational studies, obtaining a comprehensive understanding of FSI remains challenging. This report presents a comprehensive investigation, combining theoretical analysis, experimental work, and simulation of flow through a compliant tube with an internal ball added to create obstruction. An elastic PDMS tube, horizontally submerged and fixed at both ends, was equipped with a fixed ball at the center and pressure transducers at each end. Pulsatile flow was induced through the compliant tube using a peristaltic pump, with uniform flow achieved by adding a flow stabilizer. The tube's shape was monitored with a high-speed camera, and the instantaneous profile was extracted by processing video frames offline using a Python program. The pressure data and contour of the compliant tube near the obstruction were analyzed to determine the impact of the obstacles on fluid flow and pressure drop. The main conclusions include the maximum deformation of the compliant tube and the presence of hysteresis in the position of the ball. Comparisons with rigid tube pressure data revealed that the deformation of the compliant tube effectively reduces the pressure drop. This study provides insights into the pressure drop characteristics and deformation behaviors of compliant tubes in the presence of obstructions, reflecting phenomena observed in conditions such as atherosclerosis and arterial stenosis.