Application of Mixture Drift Flux Equations to Vertical Separating Flows

The one-dimensional drift flux model is widely used in the thermal-hydraulic simulation of nuclear power systems, particularly in simulator and control system modeling where faster-than-real-time solutions are necessary. During normal implementation, however, this model does not correctly simulate buoyancy-driven flows and countercurrent flow of liquid and vapor in vertical, stagnant channels. A technique is introduced that overcomes this limitation without using special component models, modifications of the equations of motion, or modifications in constitutive relations.