Modeling Nanobubble Interactions and Behavior Using Multiphase Lattice Boltzman Methods

A multiphase lattice Boltzmann model is used to explore the presence, evolution, and behavior of nanobubbles. The existence and behavior of nanobubbles has been a recent area of interest since the presence of nanobubbles challenges classical nucleation theory which dictates that bubbles below the critical radius should collapse. Nanobubbles have many areas of interest including cleaning of surfaces, nucleate boiling in microchannels, and nucleation on nanostructured materials. Multiphase Lattice Boltzmann methods (LBM) have been demonstrated to be an effective mesoscale approach to modeling multiphase flows and phase-change processes. These methods provide accurate macroscopic results while accounting for microscopic interactions without invoking an extraordinary computational cost. In this study, an LBM is used to model the evolution of nanobubbles with diameters ranging from 5 to 50 nanometers. LBM results are provided for a variety of real physical conditions that are of interest for exploring nanobubble existence within a nanoporous layer. In addition to the single nanobubble analysis, the effects of bubble interaction with smooth surfaces and within nanostructured surfaces are also presented. The results show that the hydrophilic nature of the surfaces is likely the cause of suppression in the onset of nucleate boiling which is often seen in hydrophilic nanoporous layers. The implications of these results on heat transfer applications including multiphase flows and nucleate boiling in roughened nanostructured surfaces are discussed.