Abstract
Objectives
Previous numerical models of the Realheart® used prescribed motion of the bileaflet mechanical heart valves (BMHVs) combined with an immersed solid method, which required experimental measurement of motion, and could not accurately resolve leaflet surface shear stresses. This study’s objective was to develop a modelling strategy combining computational fluid dynamics and fluid-structure interactions that predicts the motion, fluid flow characteristics, and shear stresses of the BMHVs.
Methods
Ansys Fluent 2020R2 was used to solve the laminar Navier-Stokes equations for Newtonian flow in a cylinder containing two BMHVs, representing the atrioventricular (upstream) and semilunar (downstream) valves. The atrioventricular valve underwent a prescribed vertical sinusoidal translation, but the 6 degrees of freedom solver computed the subsequent rotation of both valves using the fluid forces and moments. Overset meshing was employed for a refined mesh around the leaflet boundary. A 2-element Windkessel model was used on the outlet to represent the resistance and compliance of the downstream vasculature.
Results
The semilunar valve opened upon downward atrioventricular valve translation, and closed upon upward atrioventricular valve translation, due to backflow through the domain. The Windkessel model created realistic systolic pressure characteristics, however the large backflows required to close the semilunar valve caused unphysiological diastolic pressure characteristics.
Discussions
The full range of fluid-driven valve motion was achieved, and the overset mesh allowed mesh refinement in this critical region. This modelling strategy will now enable efficient and accurate full device simulations that investigate the interplay between different stroke parameters, efficiency, and valve leakage.
Previous numerical models of the Realheart® used prescribed motion of the bileaflet mechanical heart valves (BMHVs) combined with an immersed solid method, which required experimental measurement of motion, and could not accurately resolve leaflet surface shear stresses. This study’s objective was to develop a modelling strategy combining computational fluid dynamics and fluid-structure interactions that predicts the motion, fluid flow characteristics, and shear stresses of the BMHVs.
Methods
Ansys Fluent 2020R2 was used to solve the laminar Navier-Stokes equations for Newtonian flow in a cylinder containing two BMHVs, representing the atrioventricular (upstream) and semilunar (downstream) valves. The atrioventricular valve underwent a prescribed vertical sinusoidal translation, but the 6 degrees of freedom solver computed the subsequent rotation of both valves using the fluid forces and moments. Overset meshing was employed for a refined mesh around the leaflet boundary. A 2-element Windkessel model was used on the outlet to represent the resistance and compliance of the downstream vasculature.
Results
The semilunar valve opened upon downward atrioventricular valve translation, and closed upon upward atrioventricular valve translation, due to backflow through the domain. The Windkessel model created realistic systolic pressure characteristics, however the large backflows required to close the semilunar valve caused unphysiological diastolic pressure characteristics.
Discussions
The full range of fluid-driven valve motion was achieved, and the overset mesh allowed mesh refinement in this critical region. This modelling strategy will now enable efficient and accurate full device simulations that investigate the interplay between different stroke parameters, efficiency, and valve leakage.
| Original language | English |
|---|---|
| Publication status | Published - 10 Sept 2021 |
| Event | 47th European Society for Artificial Organs Congress - Brunel University, London, UK United Kingdom Duration: 7 Sept 2021 → 11 Oct 2021 |
Conference
| Conference | 47th European Society for Artificial Organs Congress |
|---|---|
| Country/Territory | UK United Kingdom |
| City | London |
| Period | 7/09/21 → 11/10/21 |