Hemolysis Related to Turbulent Eddy Size Distributions Using Comparisons of Experiments to Computations

Abstract

Turbulent blood flow in medical devices contributes to blood trauma, yet the exact mechanism(s) have not been fully elucidated. Local turbulent stresses, viscous stresses, and the rate of dissipation of the turbulent kinetic energy have been proffered as hypotheses to describe and predict blood damage. In this work, simulations of experiments in a Couette flow viscometer and a capillary tube were used to examine extensive properties of the turbulent flow field and to investigate contributing factors for red blood cell hemoglobin release in turbulence by eddy analysis. It was found that hemolysis occurred when dissipative eddies were comparable in size to the red blood cells. The Kolmogorov length scale was used to quantify the size of smaller turbulent eddies, indicating correspondence of hemolysis with number and surface area of eddies smaller than about 10 μm when a k-ε turbulence model is adopted.

Use of Computational Fluid Dynamics to Analyze Blood Flow, Hemolysis and Sublethal Damage to Red Blood Cells in a Bileaflet Artificial Heart Valve

“…The mean value of the absolute difference between each point in our model results and the data interpolated from [59] was calculated, as well as the mean square of this difference, and reported in Table 3. After selecting the appropriate mesh size and turbulence model based on agreement with Hutchinson and Blackmore's work, simulations of blood flow through the valve were run treating blood as a Newtonian fluid with a viscosity of 0.002 Pa·s and a density of 1050 kg/m 3 [52]. These simulations for blood were conducted to obtain KLS distributions in the flow through the valve to use for eddy analysis and hemolysis predictions.…”

“…Previous research found that eddies with size comparable to or smaller than RBCs are the most damaging [52], while those much larger than RBCs just shift the cells from their path in the overall bulk flow. The present work is focused on eddies with a diameter of 10 µm or less.…”

On the Accuracy of Hemolysis Models in Couette‐Type Blood Shearing Devices

“…Computational fluid dynamics (CFD) has been widely used in various engineering fields to solve and analyze problems that involve fluid flows . Empirical hemolysis estimation models, in conjunction with CFD simulations have been used to predict hemolysis during the development phase of VADs . Typical hemolysis models relate hemolysis to shear stresses and exposure time through a power‐law relationship …”

“…Computational fluid dynamics (CFD) has been widely used in various engineering fields to solve and analyze problems that involve fluid flows (6,7). Empirical hemolysis estimation models, in conjunction with CFD simulations have been used to predict hemolysis during the development phase of VADs (8)(9)(10)(11)(12)(13)(14)(15)(16)(17). Typical hemolysis models relate hemolysis to shear stresses and exposure time through a power-law relationship (18)(19)(20)(21)(22) where D (%) is the hemolysis index, Hb is the total hemoglobin concentration, hb represents the increase in plasma free hemoglobin, C, and are empirical constants determined by regression of the experimental data.…”

Modelagem matemática da fluidodinâmica não-newtoniana e bifásica simplificada da hemólise induzida mecanicamente em sistemas de bombeamento centrífugo de sangue

“…Até o presente, há um hiato em relação a um modelo determinístico para explicar e quantificar o processo de hemólise em bombas de sangue (Ozturk et al, 2015), (Yu et al, 2015), (Graefe et al, 2016).…”