Non-Newtonian Flow: Lumen Blood Vessel, FSI

Description

This project simulates a lumen blood vessel using coupled Fluid-Structure Interaction (FSI) and a non-Newtonian blood model in ANSYS Fluent, with the results examined through CFD analysis. 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.

The three-dimensional geometry was created in SpaceClaim. The computational domain is 164 mm long, 262 mm high, and 5 mm wide. Meshing was performed in ANSYS Meshing, producing a total of 356,794 elements. Owing to the pulsatile nature of the problem, a transient solver was used.

Methodology

Here, a blood vessel together with its wall is simulated in ANSYS Fluent. The solver's intrinsic FSI module was enabled so that displacement of the vessel wall could be captured in response to the flow.

The inlet boundary condition was defined as a pulsatile velocity using 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. A laminar model was enabled to solve the fluid equations.

Conclusion

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.