Mechanical Loading of Suspended Cells in Laminar and Turbulent Blood Flow

Prosthetic heart valves (PHVs) and other cardiovascular devices induce flow features such as turbulence, stagnation and high shear which do not occur in the native flow, and can lead to hemolysis and thrombosis due to mechanical loading of cells. As an aid to the development of cardiovascular implants, many researchers have attempted to correlate blood damage with macroscopic flow parameters through in vitro testing. The parameters most widely used are the macroscopic viscous shear stress (e.g. Paul et al. [1]) and the macroscopic Reynolds stresses in turbulent flow (e.g. Sallam and Hwang [2]). Although these quantities are valuable predictors of flow induced blood damage, they are not equivalent to the true stresses on a blood cell. In particular, Reynolds stress characterises velocity fluctuations at all length scales; therefore, it cannot completely describe the complex structure of turbulent flow on the cellular scale at which blood damage is initiated.