Lumen Blood Vessel: Non-Newtonian Flow

Lumen Blood Vessel (Non-Newtonian) — ANSYS Fluent CFD Simulation

Description

This project simulates a lumen blood vessel using coupled Fluid-Structure Interaction (FSI) together with a non-Newtonian blood model in ANSYS Fluent. Because blood is a shear-thinning fluid whose viscosity changes with the local strain rate, a non-Newtonian treatment is essential for capturing the flow behavior realistically inside the vessel — and because the elastic vessel wall deforms under the pulsating flow, the case couples the fluid and structural response. Within the FSI: Beginner CFD Training Package, this project builds on the pulsatile blood-vessel case by adding non-Newtonian blood behavior, giving a more physically realistic biomedical FSI problem.

Methodology

The three-dimensional geometry was created in SpaceClaim, with a computational domain 164 mm long, 262 mm high, and 5 mm wide, meshed in ANSYS Meshing to a total of 356,794 elements. Owing to the pulsatile nature of the problem, a transient solver was used. A blood vessel together with its wall is simulated in ANSYS Fluent, with the solver's intrinsic FSI module enabled so that the displacement of the vessel wall could be captured in response to the flow. The inlet boundary condition was defined as a pulsatile velocity through a UDF, while the outlet was defined as a pulsatile pressure, also supplied through a UDF. The blood itself was modeled as a non-Newtonian fluid using the Carreau model, which reproduces the shear-thinning drop in viscosity as the shear rate increases, and a laminar model was enabled to solve the fluid equations.

Analysis

On completion of the solution, three-dimensional contours of wall displacement and von Mises stress were obtained. As the results show, the blood flowing through the vessel exerts stress on the vessel walls, deforming them and demonstrating the two-way coupling between the pulsatile non-Newtonian flow and the compliant vessel structure. From these results you can evaluate how the pulsating blood loads the vessel wall, where the stress and deformation concentrate, and how the shear-thinning viscosity shapes the flow. By the end of this project, you'll be able to set up a coupled FSI simulation with a compliant vessel wall, apply the Carreau non-Newtonian model with UDF-defined pulsatile inlet and outlet conditions, and interpret the wall-displacement and von Mises stress fields that characterize biomedical fluid-structure interaction.