Numerical modelling of air-nanofluid bubbly flows in a vertical tube using the MUltiple-SIze-Group (MUSIG) model

The MUltiple-SIze-Group (MUSIG) model was used in this study to simulate bubbly flows of air-water and air-nanofluid in a vertical tube. Flow parameters including the void fraction, gas velocity, interfacial area concentration and Sauter mean bubble diameter were predicted and compared against the experimental data available in the literature. The model agreed well with the experimental data of air-water bubbly flow, but exhibited notable discrepancies from the data of air-nanofluid bubbly flow. With the aim to improve the MUSIG model for an effective modelling of air-nanofluid bubbly flows, some latest experimental and theoretical research outcomes were summarised and analysed. It was proposed that the key job when modelling bubbly flows of nanofluids using the MUSIG model is to address the spontaneous assembly of nanoparticles at bubble surfaces and its effects on the interfacial forces and bubble coalescence process.