On the representation of effective stress for computing hemolysis

Area of Science:

• Biomedical Engineering
• Fluid Mechanics
• Medical Device Design

Background:

• Hemolysis, or red blood cell rupture, is a critical issue in blood-circulating devices due to hydrodynamic forces.
• Existing hemolysis models, primarily based on laminar flow, often overpredict damage in complex, turbulent flow environments.
• Current methods use Reynolds stresses in power-law models, leading to inaccurate hemolysis estimations in turbulent flows.

Purpose of the Study:

• To investigate and improve the representation of effective stress in power-law hemolysis models for turbulent flows.
• To develop a more accurate method for predicting hemolysis in blood-circulating devices under various flow conditions.

Main Methods:

• Derived a new representation of effective stress from Navier-Stokes equations, linking it to energy dissipation.
• Utilized computational fluid dynamics (CFD) to obtain energy dissipation values from simulations.
• Validated the new model using a capillary tube, FDA nozzle benchmark, and a blood pump model.

Main Results:

• The proposed model, using energy dissipation to represent effective stress, significantly enhanced hemolysis prediction accuracy across diverse flow conditions.
• Prediction accuracy improved with increasing Reynolds number.
• Overprediction of hemolysis was reduced by up to two orders of magnitude compared to traditional methods.

Conclusions:

• Representing effective stress via energy dissipation offers a superior approach for hemolysis prediction in turbulent flows within blood-circulating devices.
• This method provides a more reliable tool for hemocompatibility design and optimization of medical devices.
• The findings suggest a substantial reduction in overestimation of hemolysis, leading to more accurate device assessment.