Fluid, solid and fluid–structure interaction simulations on patient-based abdominal aortic aneurysm models

Abstract

This article describes the use of fluid, solid and fluid-structure interaction simulations on three patient-based abdominal aortic aneurysm geometries. All simulations were carried out using OpenFOAM, which uses the finite volume method to solve both fluid and solid equations. Initially a fluid-only simulation was carried out on a single patient-based geometry and results from this simulation were compared with experimental results. There was good qualitative and quantitative agreement between the experimental and numerical results, suggesting that OpenFOAM is capable of predicting the main features of unsteady flow through a complex patient-based abdominal aortic aneurysm geometry. The intraluminal thrombus and arterial wall were then included, and solid stress and fluid-structure interaction simulations were performed on this, and two other patient-based abdominal aortic aneurysm geometries. It was found that the solid stress simulations resulted in an under-estimation of the maximum stress by up to 5.9% when compared with the fluid-structure interaction simulations. In the fluid-structure interaction simulations, flow induced pressure within the aneurysm was found to be up to 4.8% higher than the value of peak systolic pressure imposed in the solid stress simulations, which is likely to be the cause of the variation in the stress results. In comparing the results from the initial fluid-only simulation with results from the fluid-structure interaction simulation on the same patient, it was found that wall shear stress values varied by up to 35% between the two simulation methods. It was concluded that solid stress simulations are adequate to predict the maximum stress in an aneurysm wall, while fluid-structure interaction simulations should be performed if accurate prediction of the fluid wall shear stress is necessary. Therefore, the decision to perform fluid-structure interaction simulations should be based on the particular variables of interest in a given study.

A large strain finite volume method for orthotropic bodies with general material orientations

“…However, the usage of FV analysis in CSM is becoming increasingly popular due to the attractively simple yet strongly conservative nature of the method. At present, the FV method has been applied to a large range of stress analysis problems in linear-elasticity [1,2,3,4,5,6,7,8], thermo-elastoplasticity [9], thermo-viscoelasticity [10], incompressible elasticity [11,12], contact mechanics [14,15,16,17,18], fracture mechanics [19,20,21,22,23,24,25,26,27,28,29,30,31,32] and fluid-structure interactions [27,33,34,35].…”

Numerical Simulation of Vertebral Artery Stenosis Treated With Different Stents

“…Lantz et al investigated the WSS in a Magnetic Resonance Imaging (MRI)-based subject-specific human aorta, using both FSI and rigid wall models, and found that the influence of wall motion is low on time-averaged WSS and OSI, but when regarding instantaneous WSS values the effect from the wall motion is clearly visible [36]. Kelly et al performed fluid, solid, and FSI simulations on three patient-based abdominal aortic aneurysm geometries [37]. They concluded that solid stress simulations are adequate to predict the maximum stress in an aneurysm wall, while FSI simulations should be performed if accurate prediction of the WSS is necessary.…”

Peak Wall Stress Predicts Expansion Rate in Descending Thoracic Aortic Aneurysms

“…Traditionally, the impact of wall shear stress has been ignored, as studies in the thoracic aorta have shown it to be several orders of magnitude lower than static stresses calculated using pressure-deformation analyses [19]. Simulations using fluid-structure interactions that combine both fluid flow and solid stress have shown conflicting results in AAAs, with some studies claiming less than 5% impact on peak stress [24] and others reporting more significant increases, on the order of 20% [25]. The impact of fluid-structure interactions in TAAs represents an area of future research.…”