influence of wall compliance on flow dynamics in stenosed channels: an immersed boundary method study

Understanding the hemodynamics of stenosed arteries is essential for evaluating cardiovascular function and informing clinical interventions. this study investigates pulsatile flow through two-sided collapsible channels simulating arterial stenosis using a fluid–structure interaction (fsi) framework. a finite volume solver based on the immersed boundary method is employed to capture the coupled dynamics between pulsatile flow and compliant channel walls under physiologically realistic conditions. simulations are conducted for stenosis severities of 25%, 50%, and 75%, across heart rates of 60, 100, and 150 beats per minute (bpm), with comparative analysis between rigid and flexible wall configurations. in the compliant models, wall displacement is most pronounced at the stenosis throat due to pulsatile pressure loading, leading to dynamic lumen reshaping. this deformation produces broader, flattened velocity jets compared to the narrow, high-speed jets observed in rigid-wall cases. notably, flexible wall configurations exhibit pre-stenotic flow reversal during the diastolic phase, resulting in early recirculation zones that are absent in their rigid counterparts. in rigid models, the peak time-averaged wall shear stress (tawss) arises sharply just upstream of the stenosis, whereas in flexible walls, it shifts slightly downstream and is reduced due to the presence of persistent vortices and moderated velocity gradients. the oscillatory shear index (osi) demonstrates a wider spatial distribution in compliant arteries, driven by prolonged and asymmetric recirculation. additionally, a distinct phase lag between wall displacement and the driving pressure wave reveals viscoelastic behaviour of the arterial wall. these findings highlight the pivotal role of wall elasticity in modulating hemodynamic stresses and flow structures, emphasising the importance of fsi-based modelling for accurate prediction of blood flow in stenosed arteries.