Effect of Two-Group Void Fraction Covariance Correlations on Interfacial Drag Predictions for Two-Fluid Model Calculations in Large Diameter Pipes


Void fraction covariance has been introduced into the interfacial drag calculation used to close the one-dimensional two-fluid model. A model for void fraction covariance has been developed for large diameter pipes. The newly developed model has been compared with two previously developed models in terms of void fraction prediction accuracy. The effects of these additions on the void fraction prediction uncertainty have been evaluated utilizing a computational tool developed in MATLAB. The results indicate that there are small differences in the void fraction prediction between the models evaluated and the two-fluid model without void fraction covariance. Higher void fractions above 0.7 show the most significant changes. However, the differences in the uncertainty are not significant when compared to the uncertainty in the data used for the comparison. The results highlight a need for additional data for higher void fractions, collected with steam-water systems in large diameter pipes.


Nuclear Engineering and Radiation Science

Keywords and Phrases

Interfacial Area Transport; Large Diameter Pipe; Numerical Solution; Two-Fluid Model; Void Fraction Covariance

International Standard Serial Number (ISSN)

2661-8877; 2661-8869

Document Type

Article - Journal

Document Version


File Type





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Publication Date

01 Jun 2023