This study proposes a method of predicting hemolysis induced by turbul
ent shear stress (Reynolds stress) in a simplified orifice pipe flow.
In developing centrifugal blood pumps, there has been a serious proble
m with hemolysis at the impeller or casing edge; because of flow separ
ation and turbulence in these regions. In the present study, hemolysis
caused by turbulent shear stress must occur at high shear stress leve
ls in regions near the edge of an orifice pipe flow. We have computed
turbulent shear flow using the low-Reynolds number k - epsilon model.
We found that the computed turbulent shear stress near the edge was se
veral hundreds times that of the laminar shear stress (molecular shear
stress). The peak turbulent shear stress is much greater than that ob
tained in conventional hemolysis testing using a viscometer apparatus.
Thus, these high turbulent shear stresses should not be ignored in es
timating hemolysis in this blood flow. Using an integrated power by sh
ear force, it is optimimal to determine the threshold of the turbulent
shear stress by comparing computed stress levels with those of hemoly
sis experiments of pipe orifice blood flow.