Impact of Using Conventional Inlet/Outlet Boundary Conditions on Haemodynamic Metrics in a Subject-Specific Rabbit Aorta

Abstract

Computational fluid dynamics is a tool capable of accurately measuring metrics currently used to predict the behaviour of cardiovascular diseases. This study quantifies the impact various commonly used inlet and outlet boundary conditions have on various shear rate-based haemodynamic metrics currently used for predicting the localisation of cardiovascular diseases. Simulations are conducted on an accurately represented rabbit aorta configuration and comparison has been made against available in vivo data. The boundary conditions studied include two different inlet profiles, three outlet boundary conditions, and steady-state versus pulsatile flow cases. Large variations were found in the results, particularly when using different outlet boundary conditions, and the discrepancies were evaluated both quantitatively and qualitatively. The results clearly highlight the importance of the type of boundary condition used when simulating complex cardiovascular models. By restricting the attention to the flow within the aorta and the intercostal branches, the results suggest that prescribing transient simulation and fully developed flow at the inlet are not required. Furthermore, assuming the widely accepted low wall shear stress theory of Caro, it was found that Murray's law-based outlet boundary condition returns the most physiologically accurate results when compared to in vivo data.

Impact of heart failure severity on ventricular assist device haemodynamics: a computational study

“…This comparison highlights the importance of using a physiologically accurate BC when investigating haemodynamics within the aorta. Similar findings were found by McElroy and Keshmiri (2018) when studying the flow in an accurately represented rabbit aorta.…”

“…The localization of various lesions including atherosclerosis and thrombosis has been extensively studied and have shown to be related to different local haemodynamic metrics including some of the work of the present authors (Deyranlou et al 2020;Kabinejadian et al 2016;Keshmiri et al 2016;McElroy et al 2016a;McElroy and Keshmiri 2018;Ruiz-Soler et al 2017;Swanson et al 2020). These haemodynamic parameters can be directly derived from the flow velocity fields obtained by CFD-based simulation tools.…”

A computational simulation platform for designing real-time monitoring systems with application to COVID-19

“…Computational fluid dynamics (CFD) is one of the best solutions for this matter. In recent years, CFD has successfully been applied to numerous biomedical-related projects involving design, validation and proof-of-concept; some examples from the present authors include ( Deyranlou et al, 2020 ; McElroy and Keshmiri, 2018 ; Ruiz-Soler et al, 2017 ; Swanson et al, 2020 ).…”

Hemodynamic Abnormalities in the Aorta of Turner Syndrome Girls

“…In the absence of patient information, Murray's Law or the splitting method, both established from the power law relationship between branch diameter and flow rate, could be used ( 39 , 40 ). Several authors have favored Murray's law over the zero-pressure boundary condition, for capturing more physiologically relevant flow features ( 33 , 39 ).…”

“…Multiple studies ignore the pulsatile nature of blood flow, assuming instead a steady-state condition (25,26). This assumption is computationally-efficient when only considering the mean WSS result, but pulsatility is crucial for capturing time-dependent parameters such as instantaneous velocities and WSS, timeaveraged wall shear stress (TAWSS), transverse WSS (transWSS), oscillatory shear index (OSI), and relative residence time (RRT) (33). In addition to the above assumptions, the computational result is highly sensitive to the assigned boundary conditions (BCs) (32)(33)(34)(35)(36).…”