Wall Shear Stress Fluctuations in Collapsible Channels: Insights into Stented Artery Dynamics

Wall shear stress (WSS) serves as a crucial link between the dynamics of blood flow and the biological mechanisms that underlie various cardiovascular diseases. This study investigates WSS fluctuations in a collapsible wavy channel using a two-dimensional (2D) fluid-structure interaction (FSI) model. A combination of immersed boundary-lattice Boltzmann and the generalized interpolation material point methods solves the nonlinear coupled equations. The effects of key parameters on WSS fluctuations, including Reynolds number, pulsatile flow period, and external pressures, are analyzed for two systems: one with a wall constraint and one without the constraint. The results show that decreasing the period of pulsatile flow and increasing external pressure contribute to increased local WSS fluctuations by destabilizing the system through a fluid symmetry-breaking mechanism. Across all investigated parameter domains, the unconstrained system demonstrates a significantly enhanced ability to minimize WSS fluctuations. Since the wavy channel represents a simplified model of a stented artery, the results obtained in this study can be used to guide and optimize the stent design. The two-dimensional simulation is chosen for its low computational cost and its ability to capture key mechanisms. Future research can extend to three-dimensional models for a more comprehensive analysis.