Fluid dynamics study of an extracorporeal system for premature babies

Abstract

This thesis presents a computational fluid dynamics study of an extracorporeal membrane oxygenation (ECMO) circuit designed for premature infants. The main objective is to determine which of the four cannula configurations provided by a collaborating hospital is optimal to improve the circuit's performance from an engineering perspective. A three- dimensional model was created in ANSYS, and transient simulations were performed using a non-Newtonian Carreau model for blood and pulsatile flow conditions representative of a heart rate of 140 bpm. For each configuration, pressure and velocity fields were obtained to compute the pressure drop and wall-based indices such as the oscillatory shear index (OSI) and relative residence time (RRT). The results show that the configuration with a diameter reduction placed further downstream of the Y-connector (Case 2) has the lowest pressure drop and the most favorable hemodynamic indices among the original four designs and can therefore be considered the optimal option. Finally, a basic economic, environmental, and social analysis indicates that performing this analysis numerically enables optimization of the ECMO circuit with very low direct costs, limited environmental impact, and without exposing vulnerable patients or animal models to additional risk, while providing a quantitative basis for future experimental validation and design improvements.