Implementing boundary conditions in simulations of arterial flows

Area of Science:

• Computational fluid dynamics
• Cardiovascular modeling
• Biomedical engineering

Background:

• Computational hemodynamic models require accurate inlet/outlet boundary conditions for finite system segments.
• Classical boundary conditions use imposed pressures/flow rates or impedance filters (RLR, RLC, LR).

Purpose of the Study:

• To introduce and validate a novel unidirectional propagative approach (UPA) for modeling boundary conditions in axisymmetric Navier-Stokes equations.
• To compare UPA with traditional RLC impedance filters.
• To apply UPA to a physiological scenario involving a stented coronary artery.

Main Methods:

• Developed a unidirectional propagative approach (UPA) for inlet/outlet boundary conditions.
• Applied UPA to axisymmetric Navier-Stokes equations, achieving nonreflecting boundary conditions.
• Compared UPA performance against RLC impedance filters.
• Defined a reflection index to quantify pressure wave reflections in a stented artery model.

Main Results:

• UPA provides an effective nonreflecting boundary condition for axisymmetric arterial models.
• UPA demonstrated comparable or superior performance to the RLC impedance filter.
• The reflection index successfully quantified pressure wave reflections at arterial singularities, such as stents.

Conclusions:

• The unidirectional propagative approach (UPA) offers a robust and accurate method for implementing boundary conditions in cardiovascular hemodynamic models.
• UPA is particularly valuable for simulating complex physiological situations like stented arteries, enhancing model predictability.