A design improvement strategy for axial blood pumps using computational fluid dynamics.

During the initial stages of concept development of non traditional axial flow pumps, numeric simulation offers an attractive advantage. Computational fluid dynamics (CFD) provides the rationale to evolve the design numerically such that undesirable flow features may be significantly mitigated before a physical prototype is fabricated. The initial design of a novel axial flow blood pump is shown through CFD analysis to exhibit large regions of reverse flow. Such fluid dynamic behavior not only decreases the pump's hydrodynamic efficiency, but, more significantly, increases its overall potential for blood trauma and thrombogenesis. The design improvement strategy consists of creating a geometric model of the blood wetted surfaces and changing the associated geometric parameters such that more desirable fluid dynamic behavior is systematically attained with each incremental modification. The fluid flow through each new pump design is analyzed by numerically solving the incompressible Navier-Stokes equations in rotating coordinates. Marked improvements in the major fluid dynamic aspects of the axial flow pump were observed over an evolutionary sequence of four generations of pump design.