Abstract
In this study the interaction of blood flow with arterial wall has been investigated using FSI (Fluid-Structure Interaction) modeling. Computer simulation of pulsatile blood flow was carried out on the basis of the time dependent axisymmetric Navier-Stokes equations for an incompressible Newtonian fluid flow. An elastic incompressible material with large deformation was considered for the arterial wall and momentum and continuity equations of elastodynamics have been solved. The specified boundary conditions for the Navier-Stokes equations were the pulsatile pressure waveforms of the brachial artery at inflow and outflow to the given pulse wave form of a cardiac cycle. Fluid and solid equations were solved with the ALE-based loose coupling method for FSI problems. Resultant flow, wall displacement, wall shear stress and wall circumferential strain waves, and their phase differences were determined. Stiffening of the arterial wall resulted in a significant decrease in the mean values of flow and wall shear stress and altered waveforms. A tenfold increase in wall stiffness caused 33% drop in flow and negative values of shear stress in 21% of the pressure pulse. For elastic moduli corresponding to wall displacements less than 1% the blood flow and wall shear stress were not sensitive to wall stiffness. Stress phase angle was altered by stiffening of the arterial wall. It was concluded that FSI modeling with pressure boundary conditions provides a proper evaluation of hemodynamic parameters that may determine endothelial injury.
Highlights
It has been well established that many cardiovascular diseases are closely associated with hemodynamic parameters and vessel wall mechanical characteristics
The arterial endothelial lining is exposed to both wall shear stress caused by pulsatile blood flow and circumferential stress caused by pulsating arterial pressure
Compared to other same level arteries wall stiffness of brachial artery is lower, effects of arterial stiffening on hemodynamic parameters can be studied with more details in a wide range of elastic moduli
Summary
It has been well established that many cardiovascular diseases are closely associated with hemodynamic parameters and vessel wall mechanical characteristics. Transmission of pressure waves through the blood is the result of the energy exchange between the blood and the vessel wall; modeling of the time dependent arterial deformation or pulse propagation, is a fluid-solid interaction problem[2]. Steinman and Ethier [11] used a method similar to the one presented by Hilbert [10] They solved the fluid motion equation with a penalty function method and computed the outlet pressure with a linear wave theory, rather than prescribing experimental data. The coupling conditions ensure conservation of mass, momentum and mechanical energy on the interface
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