Investigation of vortex characteristics and energy dissipation mechanisms in the high-shear-stress flow fields of blood-handling devices

Blood-handling devices are commonly used for blood transportation or regulation, but their specialized flow channel geometries tend to create high-shear-stress flow regimes, which may induce excessive cellular damage risks and energy dissipation. To address this, this study combines computational fluid dynamics and particle image velocimetry experimental methods to establish nozzle reference models with multiple orifice diameter configurations. Based on entropy generation theory and Ω vortex identification methods, the underlying energy dissipation mechanisms and vortex dynamics under distinct high-shear-stress conditions are analyzed. The results indicate that shear flow intensity is highly correlated with energy dissipation due to entropy production. Attenuating turbulence in the flow field simultaneously suppresses shear stress damage and energy loss, while lowering shear flow intensity promotes the decomposition of vortices downstream, broadening their spatial distribution. High flow velocity alone does not directly induce shear stress or entropy-related energy dissipation; rather, an excessively steep velocity gradient is the primary factor affecting flow field safety and efficiency. A 94% rise in velocity gradient results in average increases of 97.6% in shear stress and 99.6% in energy entropy production. During flow regime transition or under pronounced velocity gradients, shear-dominated vortices readily form and generate vortex-like energy dissipation during evolution, which is a key factor exacerbating energy loss in high-shear-stress flow fields. This study elucidates the energy dissipation mechanisms and vortex dynamics in high-shear-stress flow fields of blood-handling devices, providing theoretical and technical support for optimizing flow fields and performance in relevant devices.