Direct numerical simulation of transitional flow in a stenosed carotid bifurcation

Area of Science:

• Biomedical Engineering
• Fluid Dynamics
• Cardiovascular Research

Background:

• Carotid artery stenosis is a significant risk factor for stroke.
• Understanding blood flow dynamics and biomechanical stresses is crucial for predicting disease progression and treatment outcomes.
• Subject-specific modeling offers a more accurate representation of individual patient anatomy.

Purpose of the Study:

• To numerically simulate and analyze the blood flow dynamics in a subject-specific stenosed carotid bifurcation.
• To investigate the transitional or weakly turbulent flow states and associated pressure fluctuations.
• To quantify wall shear stress (WSS) distribution and identify regions of high stress and flow separation.

Main Methods:

• Numerical simulation using the spectral element method.
• Utilized pulsatile inlet conditions derived from in vivo color Doppler ultrasound measurements.
• Analyzed velocity, pressure, and wall shear stress patterns in the stenosed internal carotid artery (ICA).

Main Results:

• Demonstrated transitional/weakly turbulent flow with rapid velocity and pressure fluctuations in the post-stenotic ICA during systole.
• Observed high-frequency vortex shedding downstream of the stenosis during systole deceleration.
• Measured high instantaneous WSS (25-45Pa) within the stenosis and high WSS gradients due to flow separation; noted oscillatory flow reversal and low pressure distal to the stenosis.

Conclusions:

• The study successfully predicted a complex in vivo flow field within a stenosed carotid artery.
• Identified significant biomechanical stresses, including high WSS and fluctuations, associated with carotid stenosis.
• Findings provide valuable insights into the hemodynamic consequences of carotid artery stenosis.