Investigating Self-Excited Oscillation in Pulsating Thin-Walled Elastic Vessels

Physiological fluid transport in thin-walled elastic vessels under pulsating conditions plays a crucial role in various processes like respiratory airflow, urinary, lymphatics, and blood flows. Self-excited oscillation can be triggered in such vessels under specific conditions of sufficiently negative transmural pressure and high Reynolds number, caused by vortex shedding and elastic wall inertia. However, the impact of pulsatile flow conditions on self-excited oscillation remains poorly understood. This study conducted experiments using a pulsatile flow loop to investigate self-excited wall oscillation under such conditions. By precisely controlling the transmural pressure with a pressure chamber and utilizing high-frequency pressure and flow sensors, along with high-speed cameras and PIV measurements, the complex fluid-structure interactions were examined. The results unveiled intricate periodic deformation patterns in the vessel wall as the pressure wave passed through it. Moreover, certain Reynolds and Womersley number conditions revealed a short period of self-excited oscillation, distinct from the pulsatile flow frequency. Notably, at a specific threshold, a transient and complete vessel collapse occurred, leading to abrupt flow closure and a sharp increase in pressure gradient. This study provides valuable insights into collapsible vessel-related diseases and serves as a benchmark for computational studies.