title: Numerical investigations of the unsteady blood flow in the end-to-side arteriovenous fistula for hemodialysis.
abstract: OBJECTIVE
  The aim of this study was to investigate the blood flow in the end-to-side arteriovenous (a-v) fistula, taking into account its pulsating nature and the patient-specific geometry of blood vessels. Computational Fluid Dynamics (CFD) methods were used for this analysis.
  
  
  METHODS
  DICOM images of the fistula, obtained from the angio-computed tomography, were a source of the data applied to develop a 3D geometrical model of the fistula. The model was meshed, then the ANSYS CFX v. 15.0 code was used to perform simulations of the flow in the vessels under analysis. Mesh independence tests were conducted. The non-Newtonian rheological model of blood and the Shear Stress Transport model of turbulence were employed. Blood vessel walls were assumed to be rigid.
  
  
  RESULTS
  Flow patterns, velocity fields, the volume flow rate, the wall shear stress (WSS) propagation on particular blood vessel walls were shown versus time. The maximal value of the blood velocity was identified in the anastomosis - the place where the artery is connected to the vein. The flow rate was calculated for all veins receiving blood.
  
  
  CONCLUSIONS
  The blood flow in the geometrically complicated a-v fistula was simulated. The values and oscillations of the WSS are the largest in the anastomosis, much lower in the artery and the lowest in the cephalic vein. A strong influence of the mesh on the results concerning the maximal and area-averaged WSS was shown. The relation between simulations of the pulsating and stationary flow under time-averaged flow conditions was presented.
authors.affiliation: Lodz University of Technology, Institute of Turbomachinery, Lodz, Poland.
authors.forename: Daniel
authors.initials: D
authors.lastname: Jodko
authors.affiliation: Lodz University of Technology, Institute of Turbomachinery, Lodz, Poland.
authors.forename: Damian
authors.initials: D
authors.lastname: Obidowski
authors.affiliation: Lodz University of Technology, Institute of Turbomachinery, Lodz, Poland.
authors.forename: Piotr
authors.initials: P
authors.lastname: Reorowicz
authors.affiliation: Lodz University of Technology, Institute of Turbomachinery, Lodz, Poland.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Jóźwik
mesh_terms: D001166:Arteriovenous Shunt, Surgical; D001783:Blood Flow Velocity / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D003198:Computer Simulation; D006801:Humans; D008955:Models, Cardiovascular; D017534:Radial Artery / Q000502:physiology* / Q000601:surgery; D033081:Shear Strength; D014655:Vascular Resistance / Q000502:physiology; D014680:Veins / Q000502:physiology* / Q000601:surgery