Analysis of Vortex-Generation Using Adaptive Finite Element Method to Simulate Hemodynamics of Sigmoid Sinus Diverticulum

Abstract

In various practical physical problems, the formation of the vortical flow inside the flow field has different effects and consequences. The diverticular vortex has been considered one of the causative factors of venous pulsatile tinnitus (PT). Thus, we aimed to solve the diverticular vortex by using the adaptive finite element method. We investigated the physical phenomena of the diverticular flow field generated during the cardiac cycles and transient changes of various physical phenomena before and after the vortex. The three-dimensional (3D) computational reconstructive geometry was created by combining computed-tomography images using MIMICS 19.0 software. Flow field calculation was performed with the software COMSOL 5.6 by implementing the 3D unsteady k-𝜔𝜔 turbulent model. The results showed that the overall state of blood flow in the sigmoid sinus and the pressure in the diverticulum changed secondarily to the cardiac cycles. Before the vortex was generated inside the diverticulum, the magnitude and the fluctuation of the inertial force in all directions become larger than those in regions without a vortex. After the appearance of the vortex, the fluctuation of its inertial force tended to be moderate at different points, and the results were similar to those regions without a vortex. The calculation of error estimates in this study met convergence, and different time intervals also exhibited expected results. The study result provides a basis for understanding the effect and cause prior to the vortex generation on venous PT.