• bubble departure
• bubble lift-off
• critical heat flux
• flow boiling
• heat partitioning
• heat transfer

Heat transfer models in multiphase flow with wall boiling rely on closure relations for bubble departure and lift-off diameters, amongst others. A critical review of different bubble departure and lift-off mechanistic models available in literature is presented: most existing models borrow modelling of individual forces from previous models and apply some calibrations, which are specific to their own experimental databases. None of the available models can be applied in a general flow boiling scenario. The proposed framework focuses on each term of force balance, leading to a more consistent and robust method to accurately predict lift-off and departure diameters. The validation against different datasets showed improved generality when compared to existing models. The developed approach has highlighted the critical aspects of modeling and indicated a development methodology that will allow a direct comparison with experimental data obtained by imaging techniques. The mechanistic model resulting from this and future works is expected to be implemented in a CFD code, to improve predictive performance of heat partitioning models. The ultimate aim of having an improved and more robust boiling heat transfer model, is the prediction of critical heat flux through delivering an accurate representation of the physics at the boiling wall.