Numerical analysis of flow in an elastic artery model

Area of Science:

• Fluid dynamics
• Biomedical engineering
• Computational mechanics

Background:

• Oscillatory and pulsatile flows in elastic tubes are fundamental to understanding blood flow dynamics.
• The "local flow" assumption simplifies complex nonlinear convective acceleration terms in fluid simulations.
• Assessing the validity of this assumption is critical for accurate hemodynamic modeling.

Purpose of the Study:

• To theoretically assess the "local flow" assumption for simulating Newtonian fluid flow in elastic tubes.
• To determine the range of validity for the "local flow" assumption by comparing it with complete flow solutions.
• To investigate the sensitivity of flow fields and wall shear stress to hemodynamic parameters.

Main Methods:

• Numerical simulation of oscillatory and pulsatile flows using the "local flow" assumption.
• Theoretical assessment and comparison with perturbation solutions of the complete flow problem.
• Analysis of flow field and wall shear stress sensitivity to the impedance phase angle.

Main Results:

• The "local flow" assumption's validity was theoretically assessed for the first time.
• Simulations demonstrated extreme sensitivity of wall shear stress to the phase angle between pressure and flow waves.
• The impedance phase angle, indicative of wave reflection, was identified as a key factor.

Conclusions:

• Subtle changes in systemic hemodynamics, specifically the impedance phase angle, can significantly alter local wall shear stress.
• This highlights a mechanism by which arterial disease and vasoactive drugs may impact local hemodynamics.
• The study provides insights into the relationship between wave reflection and wall shear stress in elastic conduits.