SIMULATION OF PRESSURE-DROP AND ENERGY-DISSIPATION FOR BLOOD-FLOW IN A HUMAN FETAL BIFURCATION

The pressure drop from the umbilical vein to the heart plays a viral p art in human fetal circulation. The bulk of the pressure drop is belie ved to take place at the inlet of the ductus venosus, a short narrow b ranch of the umbilical vein. In this study a generalized Bernoulli for mulation was deduced to estimate this pressure drop. The model contain s an energy dissipation term and flow-scaled velocities and pressures. The flow-scaled variables are related to their corresponding spatial mean velocities and pressures by certain shape factors. Further, based on physiological measurements, we established a simplified, rigid-wal led, three-dimensional computational model of the umbilical vein and d uctus venosus bifurcation for stationary flow conditions. Simulations were carried out for Reynolds numbers and umbilical vein curvature rat ios in their respective physiological ranges. The shape factors in the Bernoulli formulation were then estimated for our computational model s. They showed no significant Reynolds number or curvature ratio depen dency. Further, the energy dissipation in our models was estimated to constitute 24 to 31 percent of the pressure drop, depending on the Rey nolds number and the curvature ratio. The energy dissipation should th erefore be taken into account in pressure drop estimates.