Predicted wall shear rate gradients in T-type arteriolar bifurcations

Area of Science:

• Biomedical Engineering
• Fluid Dynamics
• Microcirculation Research

Background:

• Arteriolar bifurcations are critical sites for blood flow regulation.
• Understanding shear rate gradients is vital for microvascular health and disease.
• Previous models often simplified bifurcation geometry's role.

Purpose of the Study:

• To investigate the influence of local bifurcation geometry on shear rate gradients.
• To model Newtonian flow in divergent arteriolar bifurcations using computational fluid dynamics (CFD).
• To compare computational predictions with in vivo experimental data.

Main Methods:

• Utilized 3D CFD to simulate Newtonian flow through seven arteriolar bifurcation models with varying angles (30-150 degrees).
• Maintained constant flow split (30%) and diameter ratio (4/5).
• Observed in vivo hamster cremaster muscle microcirculation using red blood cells as flow markers.

Main Results:

• Predicted velocity profiles significantly deviated from parabolic, influenced by bifurcation geometry (angle and intersection shape).
• Shear rate along the lateral branching wall was predicted to be up to 5-fold higher than in the feed vessel.
• In vivo data confirmed significant shear rate gradients at bifurcation points, aligning with CFD predictions.

Conclusions:

• Local bifurcation geometry is a key determinant of shear rate gradients in divergent arteriolar flow.
• CFD modeling of Newtonian flow provides a good approximation of shear rate gradients under low Reynolds number (Re) conditions.
• Findings support the use of CFD for understanding microvascular hemodynamics.