Proceedings of the 15th International Heat Transfer Conference, IHTC-15 August 10-15, 2014, Kyoto, Japan IHTC15-9113 *Corresponding Author: anastasios.georgoulas@unibg.it 1 NUMERICAL INVESTIGATION OF ADIABATIC GROWTH AND DETACHMENT OF GAS/VAPOR BUBBLES INJECTED FROM A SUBMERGED ORIFICE AT VARIOUS SURFACE INCLINATIONS A. Georgoulas 1* , M. Marengo 1,2 1 Department of Engineering, University of Bergamo, Viale Marconi 5, 24044 Dalmine (BG), Italy 2 School of Computing, Engineering and Mathematics, Cockroft Building, Lewes Road, University of Brighton, Brighton, UK ABSTRACT The heat transfer mechanism of Nucleate Boiling (NB) is widely used in technological applications. However, there is an incomplete understanding of the fundamental physics of bubble dynamics, at small scales as well as at non-trivial geometrical configurations. In order to investigate bubble dynamics an adiabatic approach is often used, where gas/vapor bubbles are injected into liquids at saturation conditions. So far, there is a great deal of experimental, theoretical and numerical investigations on adiabatic gas/vapor injected bubble growth dynamics. However, according to the authors' best knowledge the majority of these works deal with gas/vapor bubbles injected upwards into stagnant liquid domains, with the injection axis being parallel to the gravitational acceleration direction, using mainly water and air as the working fluids. In the present investigation, an improved algebraic VOF (Volume of Fluid) based interface capturing approach, originally developed in OpenFOAM®, is applied for the conduction of axisymmetric and 3D numerical experiments on adiabatic bubble growth dynamics. The investigation focuses on the influence of different fluid properties and inclination angles of the gas/vapor injection orifice, on the bubble growth and detachment characteristics. Prior to the application, the predictions of the numerical model are validated against literature available experimental data. From the overall results it can be concluded that the bubble growth and detachment characteristics, are strongly dependent not only on the fluid properties but also on the orifice inclination angles due to the induced asymmetry, which mainly results from the formation of asymmetric and unsynchronized vortexes during the bubble growth process. KEY WORDS: Two-phase/Multiphase flow, Computational methods, Numerical simulation, VOF method, Adiabatic Bubble Dynamics, Bubble growth and detachment 1. INTRODUCTION The heat transfer mechanism of Nucleate Boiling (NB) is widely used in technological applications. However, the so far established theories and empirical formulations seem to be elusive. This is mainly due to an incomplete understanding of the underling physics of bubble dynamics, at small time and length scales as well as at non-trivial geometrical configurations. Due to the complexity of NB mechanism, the isolation and understanding of the influence of various controlling parameters from the bubble dynamics point of view, is very difficult. Therefore, in order to investigate bubble dynamics an adiabatic approach is often used, where gas/vapor bubbles are injected into liquids at saturation conditions. The formation of bubbles at submerged orifices, their subsequent growth and finally their detachment from the orifice mouth, constitutes a quite complex hydrodynamic process. This phenomenon finds a wide application in a variety of technological applications. The process of bubble evolution at a submerged orifice consists of two