  Many scientific and medical researchers are working towards the creation of a
virtual human - a personalised digital copy of an individual - that will assist
in a patient's diagnosis, treatment and recovery. The complex nature of living
systems means that the development of this remains a major challenge. We
describe progress in enabling the HemeLB lattice Boltzmann code to simulate 3D
macroscopic blood flow on a full human scale. Significant developments in
memory management and load balancing allow near linear scaling performance of
the code on hundreds of thousands of computer cores. Integral to the
construction of a virtual human, we also outline the implementation of a
self-coupling strategy for HemeLB. This allows simultaneous simulation of
arterial and venous vascular trees based on human-specific geometries.
