New challenge for studying flow-induced blood damage: Macroscale modeling and microscale verification

Prosthetic heart valves often induce blood cell trauma, but its mechanism is not clearly understood due to the complexity of dynamical flows. We herein propose a new challenge, termed macroscale modeling and microscale verification. This report is the former, and here we aim to clarify the physical interpretation of Reynolds stress for flowing cells. One polymer and two mechanical valves are compared, and the Reynolds stress is visualized using a novel analytical technique including time-resolved particle image velocimetry and continuous wavelet transform. The method enables to analyze the dynamics of Reynolds stress in a spatial and temporal domain. As a result, it is found that the Reynolds stress should be considered as an indicator of impinging flows for circulating cells. Such flows may impulsively apply a colliding force on a membrane of flowing cells. As microscale verification based on this new hypothesis, we are currently investigating such collision phenomena of flowing cells using high-speed microfluidic techniques.