Pulsatile Blood Flow: Arterial Bifurcation

Pulsatile Blood Flow in Arterial Bifurcation — ANSYS Fluent CFD Simulation

Description

This project presents an ANSYS Fluent simulation of time-dependent pulsatile blood flow through a simplified arterial bifurcation model. Blood flow through the arteries isn't steady — it pulses with the cardiac cycle — and reproducing that rhythmic behavior is exactly the kind of custom boundary condition a UDF makes possible. Here a User-Defined Function drives the pulsatile inlet, and the simulation reveals where an arterial bifurcation is most vulnerable to disease. Within the User-Defined Functions (UDF): Beginner CFD Training Package, this project applies the profile-macro skills to a biomedical case, using a UDF-defined transient inlet to capture the pulsating cardiac cycle.

Methodology

The fluid domain was created in Design Modeler, with mesh generation performed in ANSYS Meshing using an unstructured mesh of 168,367 elements. The blood mass flow rates are specified as 0.001570178 kg/s at the inlet and 0.00078576 kg/s at each outlet, with an inlet blood pressure of 250 Pa (approximately 1.87515 mmHg) — noting that physiological pressure in major arteries typically ranges between 80 and 120 mmHg. The pulsatile characteristics of the blood flow are captured through a User-Defined Function (UDF), which modulates the inlet velocity as a sinusoidal function of time, replicating the cardiac cycle's rhythmic nature. A transient solver provides the time-resolved flow data.

Analysis

The transient results are presented at t = 0.162 s, corresponding to peak systolic velocity, and yield clinically relevant insights into arterial pathology. The pressure-contour analysis reveals critical stress concentrations at the bifurcation apex, where the flow streams diverge: blood pressure reaches 125 Pa there — about half the inlet pressure — identifying this region as vulnerable to arterial wall rupture. The wall shear stress (WSS) distribution identifies areas susceptible to stenosis: consistent with medical literature establishing low WSS as a stenosis predictor, the bifurcation apex exhibits minimal shear-stress values, indicating heightened risk for atherosclerotic plaque development and subsequent arterial narrowing. By the end of this project, you'll be able to implement a UDF that drives a sinusoidal pulsatile inlet velocity, run a transient biomedical flow simulation, and interpret the time-resolved pressure and wall-shear-stress fields that reveal where an arterial bifurcation is prone to rupture and stenosis.