title: Experimental and Numerical Investigation of an Axial Rotary Blood Pump.
abstract: Left ventricular assist devices (LVADs) have become a standard therapy for patients with severe heart failure. As low blood trauma in LVADs is important for a good clinical outcome, the assessment of the fluid loads inside the pump is critical. More specifically, the flow features on the surfaces where the interaction between blood and artificial material happens is of great importance. Therefore, experimental data for the near-wall flows in an axial rotary blood pump were collected and directly compared to computational fluid dynamic results. For this, the flow fields based on unsteady Reynolds-averaged Navier-Stokes simulations-computational fluid dynamics (URANS-CFD) of an axial rotary blood pump were calculated and compared with experimental flow data at one typical state of operation in an enlarged model of the pump. The focus was set on the assessment of wall shear stresses (WSS) at the housing wall and rotor gap region by means of the wall-particle image velocimetry technique, and the visualization of near-wall flow structures on the inner pump surfaces by a paint erosion method. Additionally, maximum WSS and tip leakage volume flows were measured for 13 different states of operation. Good agreement between CFD and experimental data was found, which includes the location, magnitude, and direction of the maximum and minimum WSS and the presence of recirculation zones on the pump stators. The maximum WSS increased linearly with pressure head. They occurred at the upstream third of the impeller blades and exceeded the critical values with respect to hemolysis. Regions of very high shear stresses and recirculation zones could be identified and were in good agreement with simulations. URANS-CFD, which is often used for pump performance and blood damage prediction, seems to be, therefore, a valid tool for the assessment of flow fields in axial rotary blood pumps. The magnitude of maximum WSS could be confirmed and were in the order of several hundred Pascal.
authors.affiliation: Biofluid Mechanics Laboratory, Charité-Universitätsmedizin Berlin.
authors.forename: Chan Yong
authors.identifier: http://orcid.org/0000-0001-9649-3935
authors.initials: CY
authors.lastname: Schüle
authors.affiliation: Biofluid Mechanics Laboratory, Charité-Universitätsmedizin Berlin.
authors.forename: Bente
authors.initials: B
authors.lastname: Thamsen
authors.affiliation: Chair of Fluid Dynamics, Hermann-Föttinger-Institut, Technische Universität Berlin, Berlin, Germany.
authors.forename: Bastian
authors.initials: B
authors.lastname: Blümel
authors.affiliation: Biofluid Mechanics Laboratory, Charité-Universitätsmedizin Berlin.
authors.forename: Michael
authors.initials: M
authors.lastname: Lommel
authors.affiliation: Biofluid Mechanics Laboratory, Charité-Universitätsmedizin Berlin.
authors.forename: Tamer
authors.initials: T
authors.lastname: Karakaya
authors.affiliation: Chair of Fluid Dynamics, Hermann-Föttinger-Institut, Technische Universität Berlin, Berlin, Germany.
authors.forename: Christian Oliver
authors.initials: CO
authors.lastname: Paschereit
authors.affiliation: Biofluid Mechanics Laboratory, Charité-Universitätsmedizin Berlin.
authors.forename: Klaus
authors.initials: K
authors.lastname: Affeld
authors.affiliation: Biofluid Mechanics Laboratory, Charité-Universitätsmedizin Berlin.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Kertzscher
mesh_terms: D003198:Computer Simulation; D004867:Equipment Design; D006333:Heart Failure / Q000601:surgery*; D006353:Heart-Assist Devices / Q000009:adverse effects*; D006439:Hemodynamics; D006461:Hemolysis; D006801:Humans; D008955:Models, Cardiovascular; D012212:Rheology; D013314:Stress, Mechanical
keywords: Axial blood pump; Flow visualization; HeartMate II; Paint erosion method; Stokes simulations-Computational fluid dynamics; Unsteady Reynolds-averaged Navier; Wall shear stress; Wall-particle image velocimetry