Estudo numérico da hemólise em um filtro de linha arterial

Abstract

The partial or total rupture of the red cell membrane, a phenomenon known as hemolysis, is a persistent problem for blood-wetted devices. The objective of this work was to evaluate hemolysis numerically in an arterial line filter used in extracorporeal circulation circuits with the computational fluid dynamics technique. The shear stress model in the power law format is one of the most popular for estimating damage to red blood cells due to its applicability in various geometries. In this work, different Eulerian and Lagrangian implementations were compared in two benchmarks to verify and validate the model: a flow with analytical solution and a flow in medical equipment idealized in the form of a nozzle. However, it is still not well understood how the turbulent tensor directly affects red blood cells, and its application in the power law model is not recommended. Thus, an additional model was used based on the absorption of energy from the smallest eddies by the membrane of these cells and their correlation with it's rupture. In parallel, a numerical model of filter flow was created and validated with experimental data on pressure drop, dye visualization and velocity fields by particle image velocimetry. Finally, hemolysis was estimated in the filter flow from the models presented. The geometry of the filter shows hemolysis occurs mainly in the distribution channel in the entrance zone upstream of the filter element due to the formation of a jet with high speeds and a change of direction perpendicular to the flow. A direct relationship between hemolysis and the flow in the filter was proposed and can be used in comparative or optimization studies of it's design.