  Prediction of two-phase boiling flows using the computational fluid dynamics
(CFD) approach is very challenging since several sub-models for interfacial
mass, momentum and energy transfer in such flows are still not well established
and require further development and validation. Once validating a particular
model, it is important that all key parameter involved in the model are
carefully verified. Such verification is typically performed by separate effect
tests, where one parameter at a time is compared to a measured or otherwise
known value. Needless to say that for complex models, which are typical for CFD
applications to two-phase flow, the number of independent parameters that need
to be verified can be quite high. This particular feature makes the validation
process of complex CFD models in open source codes very attractive, since full
access to the implementation details is possible.
  This paper is concerned with implementation and validation of two-phase
boiling bubbly flow models using the OpenFOAM, open source environment. The
model employs the two-fluid formulation of the conservation equations with the
Reynolds-averaged treatment of the turbulent terms. The model consists of six
conservation equations for the liquid and the vapor phase, allowing for the
thermodynamic non-equilibrium and compressibility of both phases. In addition,
the model includes two transport equations for the turbulence kinetic energy
and energy dissipation and one transport equation for the interfacial area
concentration. New models for wall heat partitioning as well as for the phase
change terms in nucleate boiling have been implemented. Sensitivity studies as
well as validation of the model against measured data available in the open
literature have been performed and it has been shown that a reasonable
agreement between predictions and experiments has been achieved.

Fluid Dynamics