  The presented multi-scale, closed-loop blood circulation model includes
arterial, venous, and portal venous systems, heart-pulmonary circulation, and
micro-circulation in capillaries. One-dimensional models simulate large blood
vessel flow, whereas zerodimensional models are used for simulating blood flow
in vascular subsystems corresponding to peripheral arteries and organs.
Transmission conditions at bifurcation and confluence are solved using Riemann
invariants. Blood circulation simulation in the portal venous system and
related organs (liver, stomach, spleen, pancreas, intestine) is particularly
targeted. Those organs play important roles in metabolic system dynamics. The
proposed efficient parallel algorithms for multicore environments solve these
equations much faster than serial computations.
