Analisis Aliran Darah Pseudoplastik di Sekitar Penyumbatan Parsial Pembuluh Retina dengan Pendekatan Non-Newtonian

Abstract

Retinal Vein Occlusion (RVO) is one of the retinal vascular disorders characterized by blood flow obstruction due to partial venous blockage. To realistically represent this phenomenon, a blood flow model capable of capturing changes in viscosity due to variations in local shear rate within the vessel is required. In this study, blood flow is modeled as a non-Newtonian fluid using the Carreau–Yasuda approach, which mathematically provides a smooth viscosity transition from stagnant (low shear) to high shear conditions. The occlusion zone is modeled as a porous domain with low permeability, forming a multi-domain system between free fluid and resistive media. The simulation is carried out numerically using COMSOL Multiphysics software, with sinusoidal boundary conditions representing cardiac pulsation. Calculations are performed over three cardiac cycles, and analysis is focused on the steady phase of the third cycle (1.6–2.4 seconds). The results show a significant pressure drop across the stenosis zone, with a distal-to-proximal pressure ratio of 0.615 at t = 2 seconds, indicating the presence of partial RVO hemodynamic disturbance. The non-Newtonian viscosity model captures the pressure gradient variations and velocity distribution that depend on local shear fields—something that cannot be represented by conventional Newtonian models. Therefore, this approach offers a more accurate and stable mathematical basis for simulating retinal stenosis.