In order to enhance the prediction capability of subcooled boiling flows, an advanced wall boiling
model and mechanistic bubbles size model were examined using a CFD (Computational Fluid
Dynamics) code. The advanced wall boiling model consists of a mechanistic bubble departure size
model (Klausner et al., 1993), Hibiki et al.’s (2009) active nucleate site density model and Cole’s
(1960) bubble departure frequency model. To ensure a wide range applicability of the advanced wall
boiling model, each sub-model was evaluated separately over a wide range of flow conditions in
pressure, temperature and flow rate. Finally, the advanced wall boiling model was implemented into
the commercial CFD code STAR-CD via user FORTRAN files.
For an accurate prediction of bubble size which governs interfacial transfer terms between the two
phases, the Sγ model (Lo et al., 2009) was also applied.
The benchmark calculation against the DEBORA subcooled boiling data confirms that the new
mechanistic wall boiling and bubble size models follow well the tendency on the change of flow
conditions and are applicable to the wide range of flow conditions that are expected in the nominal and
postulated accidental conditions of a nuclear power plant.