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 vital part in human fetal circulation. The bulk of the pressure drop is bel ieved to take place at the inlet of the ductus venosus, a short narro w branch of the umbilical vein. In this study a generalized Bernoulli formulation was deduced to estimate this pressure drop. Further, bas ed on physiological measurements, we established a simplified,rigid-w alled, three-dimensional computational model of the umbilical vein an d ductus venosus bifurcation for stationary flow conditions. Simulat ions were carried out for Reynolds numbers and umbilical vein curvatu re ratios in their respective physiological ranges. The shape factor s in the Bernoulli formulation were then estimated for our computatio nal models. They showed no significant Reynolds number or curvature ratio dependency. Further, the energy dissipation in our models was estimated to constitute 24 to 31 percent of the pressure drop, depend ing on the Reynolds number and the curvature ratio. The energy dissi pation should therefore be taken into account in pressure drop estima tes.