Arti¯cial prostheses create non-physiologic °ow conditions with stress forces that may induce blood cell damage, particularly hemolysis. Earlier computational °uid dynamics (CFD) prediction models based on a quanti¯ed power model showed signi¯cant discrepancies with actual hemolysis experiments. These models used the premise that shear stresses act as the primary force behind hemolysis. However, additional studies have suggested that extensional stresses play a more substantial role than previously thought and should be taken into account in hemolysis models. We compared extensional and shear stress °ow ¯elds within the contraction of a short capillary with sharp versus tapered entrances. The °ow ¯eld was calculated with CFD to determine stress values, and hemolysis experiments with porcine
red blood cells were performed to correlate the e®ects of extensional and shear stress on hemolysis. Our results support extensional stress as the primary mechanical force involved in hemolysis, with a threshold value of 1000 Pa under exposure time less than 0.060 ms.
Biomedical Engineering: Applications, Basis and Communications 27(5), pp.1550042(11 pages)