Non-Newtonian blood flow through our arteries is a fascinating subject that affects everyone’s health! Unlike water which flows simply, blood behaves in special ways because it’s made of many tiny parts swimming in plasma. First of all, when your heart beats, it creates pulsatile flow that pushes blood through your vessels in waves, not in a steady stream. Additionally, blood viscosity (how thick and sticky it is) changes depending on how fast it moves through different parts of your cardiovascular system. Moreover, this changing thickness is what makes blood a non-Newtonian fluid – it doesn’t follow simple flow rules like water does. Most importantly, understanding non-Newtonian blood flow helps doctors predict and treat dangerous conditions like atherosclerosis (clogged arteries) and aneurysms (bulging vessel walls). Advanced CFD simulation of blood hemodynamics is crucial for designing better medical devices like stents and artificial heart valves, potentially saving millions of lives by working with—not against—the unique properties of non-Newtonian blood in the human body.

Simulation Process

*** Mesh Independence study: A mesh independence study is conducted for the current project to find the most accurate grid with the least computational cost. The table represents the results:

After thorough analysis, the grid with 570571 cells is selected.

The artery geometry model is created based on authentic MRI images. It should be considered that blood behaves similarly to a non-Newtonian fluid, so it requires preliminary steps to relate viscosity and shear stress via using the Correau model. A user-defined function (UDF) is particularly written in C language to apply pulse effects for blood inlet boundary. Interestingly, massless particles are carried by blood flow (Discrete Phase Model (DPM)). It is done to track blood components path along the artery.

Figure 1: Pulsatile blood flow in Artery

Post-processing

The particle tracking contour show us how blood cells move through your arteries! In the first image, we can see colorful dots scattered throughout a branching artery, with each dot representing tiny blood components. Our simulation successfully tracked over 850 individual particles as they traveled through this complex path. The particles stay inside the artery for nearly one second (between 0.910 and 1.00 seconds), which is just the right amount of time for oxygen delivery. Also, notice how most particles cluster along certain preferred paths instead of spreading out evenly! Furthermore, the branching area (bifurcation) causes some particles to slow down and linger longer. This matches exactly what happens in real human arteries! The non-Newtonian behavior of blood means it flows differently than water would, especially in these tricky curved and branching sections.

Figure 2: Particle residence time visualization showing blood component distribution

The second contour reveals the amazing flow paths that blood cells follow through your arteries! Instead of moving in straight lines, blood creates beautiful curved streams that twist and bend with the artery shape. We successfully mapped complete pathlines for all 851 particles, showing how your blood navigates through both the main artery and its branches. Additionally, some paths stay near the center of the vessels while others swing closer to the walls, creating a complex pattern. Most importantly, our pulsatile flow model shows that when your heart pushes blood in pulses (not steady streams), it creates special flow patterns that help blood cells reach every part of your body. The blood viscosity changes as it moves through narrow spots, which is exactly why we needed to use the special Carreau model for this simulation! Understanding these pathways helps doctors know exactly how medicines travel through your bloodstream and how dangerous clots might form in certain spots.

Figure 3: Blood flow pathlines colored by particle ID