Figure 1

Resulting mass fraction of blood demonstrating the infusion of saline into the vein (left column) and the scenario without infusion (right column). Geometry shown is the 20 gauge (G), 20° insertion angle, positioned at the vessel edge. Only part of the geometry is shown and the images show a plane central through the catheter-vein geometry. The color bar refers to both the contours in the top row and the streamlines shown throughout. At this infusion rate (300 mL/min) the vein is practically cleared of blood and an area of recirculation (highlighted) is observed proximal to the catheter tip. In this zone the ratio of blood to saline is approximately 50:50. In the presence of the catheter, but without saline infusion, a region of recirculating blood (highlighted) is seen at the tip of the catheter.