An Approach on Fluid-Structure Interaction for the Prediction of Blood Flow in Aneurysms With Various Shapes

Author(s):  
Sang Hyuk Lee ◽  
Nahmkeon Hur ◽  
Seongwon Kang

Recently, the rapid evolution of numerical methodologies for CFD and structural analyses has made it possible to predict the arterial hemodynamics closely related to vascular disease. In the present study, a framework for fluid-structure interaction (FSI) analysis was developed to accurately predict the arterial hemodynamics. The numerical results from the FSI analysis of the hemodynamics inside aneurysms of various shapes were compared to the results without FSI analysis. The results showed that FSI analysis needs to be performed in order to accurately predict the blood flow affected by the wall motion of compliant arteries. FSI analysis is essential to predict the hemodynamics in a saccular aneurysm because the arterial wall’s movement, which is a result of the variation of blood pressure in the aneurysmal sac, mainly produces the blood flow to a saccular aneurysm.

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Fan He ◽  
Lu Hua ◽  
Tingting Guo

Abstract Background The effects of arterial wall compliance on blood flow have been revealed using fluid-structure interaction in last decades. However, microcirculation is not considered in previous researches. In fact, microcirculation plays a key role in regulating blood flow. Therefore, it is very necessary to involve microcirculation in arterial hemodynamics. Objective The main purpose of the present study is to investigate how wall compliance affects the flow characteristics and to establish the comparisons of these flow variables with rigid wall when microcirculation is considered. Methods We present numerical modeling in arterial hemodynamics incorporating fluid-structure interaction and microcirculation. A novel outlet boundary condition is employed to prescribe microcirculation in an idealised model. Results The novel finding in this work is that wall compliance under the consideration of microcirculation leads to the increase of wall shear stress in contrast to rigid wall, contrary to the traditional result that wall compliance makes wall shear stress decrease when a constant or time dependent pressure is specified at an outlet. Conclusions This work provides the valuable study of hemodynamics under physiological and realistic boundary conditions and proves that wall compliance may have a positive impact on wall shear stress based on this model. This methodology in this paper could be used in real model simulations.


Perfusion ◽  
2021 ◽  
pp. 026765912199854
Author(s):  
Mohammad Javad Ghasemi Pour ◽  
Kamran Hassani ◽  
Morteza Khayat ◽  
Shahram Etemadi Haghighi

Background and objectives: Fluid structure interaction (FSI) is defined as interaction of the structures with contacting fluids. The aortic valve experiences the interaction with blood flow in systolic phase. In this study, we have tried to predict the hemodynamics of blood flow through a normal and stenotic aortic valve in two relaxation and exercise conditions using a three-dimensional FSI method. Methods: The aorta valve was modeled as a three-dimensional geometry including a normal model and two others with 25% and 50% stenosis. The geometry of the aortic valve was extracted from CT images and the models were generated by MMIMCS software and then they were implemented in ANSYS software. The pulsatile flow rate was used for all cases and the numerical simulations were conducted based on a time-dependent domain. Results: The obtained results including the velocity, pressure, and shear stress contours in different systolic time sequences were explained and discussed. The maximum blood flow velocity in relaxation phase was obtained 1.62 m/s (normal valve), 3.78 m/s (25% stenosed valve), and 4.73 m/s (50% stenosed valve). In exercise condition, the maximum velocities are 2.86, 4.32, and 5.42 m/s respectively. The maximum blood pressure in relaxation phase was calculated 111.45 mmHg (normal), 148.66 mmHg (25% stenosed), and 164.21 mmHg (50% stenosed). However, the calculated values in exercise situation were 129.57, 163.58, and 191.26 mmHg. The validation of the predicted results was also conducted using existing literature. Conclusions: We believe that such model are useful tools for biomechanical experts. The further studies should be done using experimental data and the data are implemented on the boundary conditions for better comparison of the results.


2021 ◽  
Vol 11 (2) ◽  
pp. 13-16
Author(s):  
Artur Ovsepyan ◽  
Alexander Smirnov ◽  
Sergey Dydykin ◽  
Yuriy Vasil'ev ◽  
Evgeniy Trunin ◽  
...  

The interaction of the blood flow with the aorta is a complex dynamic event described in biomechanics as the Fluid-structure interaction. In this study we’ve developed a method for creation of a personalized 3D dynamic model of the aortic bulb and arch for the prediction of its mechanical behavior using FSI-analysis. We found that the accuracy of predicting geometric aortic deformities based on FSI modeling is on average 92%.


Author(s):  
Ahmad Moghaddaszade-Kermani ◽  
Peter Oshkai ◽  
Afzal Suleman

Mitral-Septal contact has been proven to be the cause of obstruction in the left ventricle with hypertrophic cardiomyopathy (HC). This paper presents a study on the fluid mechanics of obstruction using two-way loosely coupled fluid-structure interaction (FSI) methodology. A parametric model for the geometry of the diseased left ventricular cavity, myocardium and mitral valve has been developed, using the dimensions extracted from magnetic resonance images. The three-element Windkessel model [1] was modified for HC and solved to introduce pressure boundary condition to the aortic aperture in the systolic phase. The FSI algorithm starts at the beginning of systolic phase by applying the left ventricular pressure to the internal surface of the myocardium to contract the muscle. The displacements of the myocardium and mitral leaflets were calculated using the nonlinear finite element hyperelastic model [2] and subsequently transferred to the fluid domain. The fluid mesh was moved accordingly and the Navier-Stokes equations were solved in the laminar regime with the new mesh using the finite volume method. In the next time step, the left ventricular pressure was increased to contract the muscle further and the same procedure was repeated for the fluid solution. The results show that blood flow jet applies a drag force to the mitral leaflets which in turn causes the leaflet to deform toward the septum thus creating a narrow passage and possible obstruction.


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