Effects of Phase Relationships on Wall Shear Stress in Curved and Straight Elastic Artery Models

Abstract

Wall shear stress, diameter and flow waveforms were measured in elastic curved and straight tube physical models under sinusoidal flow conditions with up to 11% diameter variation. The straight tube experiments were simulated with a theoretical model. Both the experiments and the theoretical model predict extreme sensitivity of wall shear stress to the phase angle between wall shear stress and diameter. Under fixed flow waveform conditions, the experiments showed as much as a five-fold increase in wall shear stress over a 20–40 deg change in phase angle. The onset of strong wall shear stress reversal was also observed in this sensitive phase angle range. Even greater effects were predicted by the theoretical model which covered a broader range of phase angle variations. These results suggest that wall elasticity may play an important role in determining wall shear stress distributions in large arteries.