Blood Flow in a Coronary Bifurcation: Paper Validation

Blood Flow in a Coronary Bifurcation, Paper Numerical Validation, ANSYS Fluent

Description

This project is based on the reference paper "Numerical investigation of blood flow in a deformable coronary bifurcation and non-planar branch," which numerically investigates pulsatile blood flow through a coronary bifurcation featuring a non-planar branch, with the vessel wall assumed compliant to reflect more realistic physiological behavior.

Identifying and assessing hemodynamic characteristics is critical to understanding and preventing cardiovascular disease, since stenosis development depends heavily on local blood flow behavior — and given the high mortality and morbidity associated with coronary artery disease, these hemodynamic characteristics warrant close attention. This simulation examines the effects of wall compliance and blood's non-Newtonian rheology on flow behavior using ANSYS Fluent, with results compared and validated against the reference article's published data.

The study evaluates how non-Newtonian blood behavior, wall compliance, and varying bifurcation angles together shape hemodynamic flow characteristics, with blood's shear-thinning behavior captured using the Carreau-Yasuda model. Since atherosclerosis develops predominantly at bifurcations, this research focuses specifically on flow behavior in these regions, identifying the low-shear-stress zones most prone to stenosis development. The pulsatile inlet velocity profile was derived using MATLAB and implemented in Fluent through a custom UDF.

Geometry & Mesh

The geometry was designed in Gambit. Meshing used a starting element size of 0.25, a growth rate of 1.25, and a maximum size of 0.5, producing a mesh of 397,388 elements.

Methodology

Several assumptions were applied: a pressure-based solver was used, the energy equation was disabled, the simulation was run as unsteady, and gravitational effects were included.

Key simulation settings included:

• Material properties: Blood modeled with a density of 1050 kg/m³ and viscosity governed by the Carreau model

• Boundary conditions: Both outlets set to 0 Pa gauge pressure; vessel wall with no-slip condition; inlet velocity defined via UDF to capture the pulsatile profile

• Turbulence model: Laminar, with the energy equation disabled

• Dynamic mesh: Smoothing method using a linearly elastic solid formulation, with the vessel wall defined as a deforming boundary to capture wall compliance

• Solution methods: SIMPLE pressure-velocity coupling, with second-order upwind discretization for both pressure and momentum

• Initialization: Hybrid method

• Run settings: 35 time steps at a step size of 0.01, with a maximum of 200 iterations per step

Conclusion

Validation was performed using Figure 6 of the reference article, which presents wall shear stress along the coronary vessel walls as a function of distance from the bifurcation. The wall shear stress values from this simulation were extracted along Line 3 (as defined in Figure 1 of the article) and compared directly against the reference results, with the comparison presented in the accompanying image set — confirming that the current numerical setup successfully reproduces the hemodynamic behavior reported in the original study.