These are the five-outlets model and the profunda femoris model used in the referenced paper.
The five-outlets model is composed by joining five identical short pipes and a longer pipe all converging on a single point. It is a simplified model of the aortic arch with five branches.
The profunda femoris model is extracted from the anatomical model given in the reference. It is a model of an artery in the right thigh of humans.
These models can be converted to the .gmy format adopted by HemeLB using the voxeliser here.