Yildirim, Orhan; Karagoz, Sendogan; Sonmez, Fatin; Firat, Ilker

This study aims to develop an experimental platform that emulates the human cardiovascular system to investigate the effects of varying pulse rates and fluid properties on pressure drop, peristaltic pump output pressure, and power consumption. To support the experimental findings, computational fluid dynamics (CFD) simulations were conducted to analyze single-phase blood flow dynamics. Idealized arterial geometries representing healthy (0% stenosis) and diseased (65% stenosis) conditions were reconstructed from computed tomography (CT) images. A non-Newtonian blood-mimicking fluid (XSCN) was formulated to better replicate the rheological behavior of blood, while distilled water was used as the Newtonian reference fluid. Experiments were conducted at six different pulse rates: 72, 84, 96, 114, 132, and 156 beats per minute (bpm). The experimental setup was replicated in a virtual environment using ANSYS Fluent to simulate flow behavior under identical boundary conditions. The results demonstrate that increasing pulse rate leads to an increase in pressure drop (ΔP), pump output pressure, and power consumption for both arterial models. These effects were more pronounced in the stenosed artery due to flow constriction. Elevated turbulence intensity was observed at higher pulse rates, with notable differences between Newtonian and non-Newtonian fluids, particularly in terms of flow resistance and shear-dependent viscosity. Power consumption was found to be directly correlated with fluid viscosity, which varied with shear rate in the non-Newtonian fluid. The 65% stenosed model consistently exhibited higher pressure drops and flow irregularities. Fractional flow reserve (FFR) analysis confirmed that a 65% luminal narrowing poses significant hemodynamic risk. The highest wall shear stress (WSS) values were localized in the stenotic region, contributing to disturbed flow patterns and increased turbulence downstream. The non-Newtonian fluid model revealed that WSS was more sensitive to flow alterations, emphasizing the role of shear-dependent viscosity in vascular hemodynamics. These findings underscore the critical influence of hemodynamic parameters—such as pulse rate, viscosity, and arterial geometry—on cardiovascular performance. The study further highlights the detrimental impact of arterial stenosis on blood flow behavior and energy expenditure, with implications for clinical diagnosis and treatment planning in cardiovascular diseases.

Sonmez, Fatin; Karagoz, Sendogan; Yildirim, Orhan; Firat, Ilker

The study was carried out to investigate the effect of the artery with different pulse values and stenosis rates on the pressure drop, the peristaltic pump outlet pressure, fractional flow reserve (FFR) and most importantly the amount of power consumed by the peristaltic pump. For this purpose, images taken from the clinical environment were produced as models (10 mm inlet diameter) with 0% and 70% percent areal stenosis rates (PSR) on a three-dimensional (3D) printer. In the experimental system, pure water was used as the fluid at 54, 84, 114, 132, and 168 bpm pulse values. In addition, computational fluid dynamics (CFD) analyzes of the test region were performed using experimental boundary conditions with the help of ANSYS-Fluent software. The findings showed that as PSR increases in the arteries, the pressure drop in the stenosis region increases and this amount increases dramatically with increasing effort. An increase of approximately 40% was observed in the pump outlet pressure value from 54 bpm to 168 bpm in the PSR 0% model and 51% increase in the PSR 70% model. It has been observed that the pump does more work to overcome the increased pressure difference due to increased pulse rate and PSR. With the effect of contraction, the power consumption of the pump increased from 9.2% for 54 bpm to 13.8% for 168 bpm. In both models, the Wall Shear Stress (WSS) increased significantly. WSS increased abruptly in the stenosis and arcuate regions, while sudden decreases were observed in the flow separation region.