Two-phase Analysis of Bifurcation Angle Effect on Blood Heat Transfer in Three-Dimensional Bifurcated Vessels

Abstract

Background and Objective: Bifurcated blood vessels (symmetric and asymmetric) are major contributors to the heat sink effect which causes incomplete tumor cell necrosis during the thermal ablation procedure. This study analyses the effect of bifurcation angle on blood heat transfer using a two-phase numerical model. Methods: Three-dimensional bifurcated blood vessels having two different diameters (case 1: diameter = 3 mm and case 2: diameter = 0.6 mm) are being constructed with both symmetric and asymmetric configurations. The Eulerian two-phase model (Granular model along with the application of kinetic theory) is used for blood flow simulation in bifurcated vessels. Results: The effect of vessel diameter and bifurcation angle on the blood heat sink is being studied in a three-dimensional bifurcated vessel. Minimum blood temperature at bifurcation which is responsible for the major heat sink effect, is noticed to have a higher value for small vessels compared to large. As the angle ratio (r = α/β) in a small diameter bifurcated vessel with asymmetric configuration increases, blood velocity at the inlet of branch vessel 1 decreases, which lowers the heat sink effect produced due to blood flow at the bifurcation. In a large diameter (D_m = 3 mm) bifurcated vessel with symmetric configuration, with an increase in bifurcation angle (Ω_bif), blood heat transfer at the inlet of branch vessel 1 and heat sink effect of blood at bifurcation both increase. Conclusion: Both bifurcation angle, symmetricity, and vessel diameter size have pronounced effects on blood heat transfer in a bifurcated vessel. This study concludes that during hyperthermia or cryo-therapy, the nearby vasculature configuration type must be taken into account to achieve maximum efficacy of the ablation procedure.